" I would like to correct you regarding Ducati 250/350 heads. "
____ Thanks very-much for bothering to share your advanced knowledge Nigel ! _ As it's always cool to learn such details !
" As your experience may well be mostly with Narrowcase models, "
____ Actually my experience with w-c.type OHC.heads is only slightly less than that with the n-c.heads.
__ I've mentioned in an older post exactly how many differing OHC.heads Ducati produced for all their various std.production single-cylinder Duke-models, (but for the moment, I'm thinking that there were about 8 varied models).
" all Italian Narrowcase 250 have a head diameter to the edge of the squish of 74mm and a squish angle of 45 degrees. The 350 Sebring has a head diameter of 76mm and a squish angle of 40 degrees. "
____ Thanks for that Nigel, as I don't think I've ever before realized that their was any such noteworthy difference in those head's squish-angles.
" However with all Italian widecase models all the 250 & 350 heads are 74mm with a squish angle of 45 degrees therefore 250 and 350 widecase heads are identical. "
____ Now that's something-else which I don't think I ever bothered to take note of, as I guess I probably assumed that both n-c & w-c 350-heads would've all been machined identically in that particular (74mm bore-size dia.) regard.
I had actually realized that that was indeed the case with all 250/350 'replacment-heads', but I now guess I may have assumed that original factory-installed w-c.350-heads were also 76mm just like the n-c 350-head. _ Your claim now makes me want to go check all my w-c 350 heads, cuz I don't see how I could've simply assumed what I had thought as fact, for so many years !
" The factory obviously did this for interchangeability "
____ I think the interchangeability was merely a side-benefit, and the real reason behind it was to cut-down on production-costs (as usually was commonly done, due to their I.gov. regularly being on their case).
" For identification: All narrowcase heads have a gasket face surface that the cam end cap sits on similar shape to the cap, with cast in recesses either side of the scallops of the cap. All Italian Widecase models are slab sided across this face. "
____ I think I know/understand what you're meaning to say here, (but,
I must excuse your use of the word "All", in regards to "Italian Widecase"),
however it would still be nice to have some pictures to actually SHOW exactly what you specifically mean.
I'll take a stab at explaining it myself, in other words & from an alternate manor of looking at it...
__ As most-all DUKERs already realize, there are two different shapes for the '250' & '350' type, and, the 'DESMO' type, of camshaft-tip bearing-support end-cap/covers. ...
And in this area of the cyl.head where a gasket is fitted-between it and the cap/cover, all n-c.250/350-heads' gasket mating-surface-area is the very-same shape as that of the intended gasket & cap/cover -(with either "250" or "350" embossed).
Whereas with LATER-model w-c.250/350 cyl.head-models, that same area of the head, (whether DESMO or not), rather-instead has a mating-surface-area that's shaped like a "DESMO" cap/cover !
That newer feature certainly externally distinguishes such a w-c.head from a n-c.head !
However, those type of w-c.heads did not appear, (at least here in the U.S.), until late-1969,, as before then, all w-c.springer-heads appeared (externally) the same as n-c.heads !
And also as well,, while I suppose that there were possibly intermediate exceptions (around the point of changeover), all 1967 to 69 w-c.engines were fitted with SSI-carbs, while the 'later' 1969 & newer w-c.heads (with the DESMO-appearing cap/cover mating-surface), happen to (pretty-much all) come-stock with the 'square-slide' type Del.carbs.
__ It also would've been logically-neat if that obvious external identification feature had actually began with the very-first of the w-c.heads, but such concerting-change was not actually the case, (AT-LEAST for the actual 1967 model-year !), on THIS FACT, I stand FIRM !
" Moving on to widecase Spanish heads, these revert to a cam end cap face on the head as per the narrowcase bikes. "
____ On this matter,, I as well, know that to be true also.
It's just one example (of many) where it seems that Mototrans took-over Ducati's old/obsolete motor-designs.
" The Widecase Spanish 250 is 74mm or 75mm and 350 76mm or 77mm, I am sure Jon Pegler could firm up these dimension. "
____ Are you referring to the cyl.bore-size or the head's combustion-chamber O.D. ?
" Spanish 250 Narrowcase models are of course 66mm. "
____ "66mm" ? _ I thought that was the 'stroke', (not the 'bore').
Isn't the bore-size of one of the 250-Mototrans models actually '69mm' ?
" I guess if the head you have Bob is from the states, it will almost certainly be an Italian head so this warning probably does not apply to you. "
____ No, of-course not,, cuz as I had previously explained (in my prior post), it's the newer-type of w-c.springer-head which seemingly appears as if it could possibly have a 'DESMO' type cap/cover installed/matched in-place.
____ Thanks again for your contribution of Duke-knowledge Nigel !
Enlightened-Cheers,
-Bob
wanted 350 widecase head
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DewCatTea-Bob
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Variances of 250/350 Cylinder-heads
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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LaceyDucati
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Re: wanted 350 widecase head
Bob
Ok I stand corrected if the Early widecase models had the same heads as narrowcases. Not many Early widecases were sold here in the UK, as our market was flooded with much cheaper "grey imported" US rejected square style narrowcase models which were still being sold in the early 70's.
I have the best part of a very early 250 W/C scrambler rolling chassis. Which I am going to restore/ build as a complete bike, to as near as original as possible (one day!) I was unaware in the the UK it existed as a model (defiantly not imported here). It is meantioned in Mick Walkers book as a "prototype". It has a tank similar to the narrowcase scrambler and has no lower loops under where on a mark 3 the tool boxes are. The mudguards are also of different section to later scramblers. There is so little information about these bikes written so any info or knowledge you may have would be appreciated. Maybe I should use a narrowcase head
I meant 69mm, brain fade!
I was meaning cost cutting in manufacturing, when I mentioned interchangeability.
With the Spanish widecase heads I was reffering to the head diameter at the edge of the squish. Something tells me they are not 74mm & 76mm, just an element of doubt. But they are distinguishable very easily from other respects. As I mentioned I don't use them for race use so I wouldn’t have studied this size in any detail.
I have taken some pictures which I will put up later, There are marginal casting diferences on the widecase heads through the years as well, I was trying to generalise and not get to bogged down in detail. As you say once you get into differences with valve and port sizes that's a different story.
If your head is as I described slab sided ( like a Desmo cap) then it will be Italian as I have never seen a Spanish head like this. Some very Late Italian engines (75) had Spanish heads and other components, just to confuse the situation further!
Nigel
Ok I stand corrected if the Early widecase models had the same heads as narrowcases. Not many Early widecases were sold here in the UK, as our market was flooded with much cheaper "grey imported" US rejected square style narrowcase models which were still being sold in the early 70's.
I have the best part of a very early 250 W/C scrambler rolling chassis. Which I am going to restore/ build as a complete bike, to as near as original as possible (one day!) I was unaware in the the UK it existed as a model (defiantly not imported here). It is meantioned in Mick Walkers book as a "prototype". It has a tank similar to the narrowcase scrambler and has no lower loops under where on a mark 3 the tool boxes are. The mudguards are also of different section to later scramblers. There is so little information about these bikes written so any info or knowledge you may have would be appreciated. Maybe I should use a narrowcase head
I meant 69mm, brain fade!
I was meaning cost cutting in manufacturing, when I mentioned interchangeability.
With the Spanish widecase heads I was reffering to the head diameter at the edge of the squish. Something tells me they are not 74mm & 76mm, just an element of doubt. But they are distinguishable very easily from other respects. As I mentioned I don't use them for race use so I wouldn’t have studied this size in any detail.
I have taken some pictures which I will put up later, There are marginal casting diferences on the widecase heads through the years as well, I was trying to generalise and not get to bogged down in detail. As you say once you get into differences with valve and port sizes that's a different story.
If your head is as I described slab sided ( like a Desmo cap) then it will be Italian as I have never seen a Spanish head like this. Some very Late Italian engines (75) had Spanish heads and other components, just to confuse the situation further!
Nigel
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LaceyDucati
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Re: wanted 350 widecase head
Pictures showing gasket face area differences.
Pictures show the "narrowcase" (possibly early widecase as Bob said), and as all Spanish heads.
the next model widecase, still slightly following the Desmo shaped cap
and the last model widecase (completely "slab sided") .
I have also added two other photos showing the obvious exterior difference between a spring valve and Desmo. Yes I know it says Desmo on the End cap, but in my experience don't believe everything you read
Pictures show the "narrowcase" (possibly early widecase as Bob said), and as all Spanish heads.
the next model widecase, still slightly following the Desmo shaped cap
and the last model widecase (completely "slab sided") .
I have also added two other photos showing the obvious exterior difference between a spring valve and Desmo. Yes I know it says Desmo on the End cap, but in my experience don't believe everything you read
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DewCatTea-Bob
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Variances of 250/350 Cylinder-heads
" Ok I stand corrected if the Early widecase models had the same heads as narrowcases. "
____ Well actually the early 350 w-c.heads were not the same as the n-c.Sebring-head...
The port-size is 29.5mm instead of 26.5mm, and they have the larger valve-seats. _ However I can't (now) confirm whether the squish-band is the same (width & angle) as the Sebring-head. _ But considering what you've pointed-out about the w-c.350-piston, I'd figure not.
" Not many Early widecases were sold here in the UK, as our market was flooded with much cheaper "grey imported" US rejected square style narrowcase models which were still being sold in the early 70's. "
____ Yes that big mess-up was a fiasco ! _ Berliner should've been FORCED to accept that rejected production-batch of n-c.Duke-models, even if they then had to sell them at no profit. _ But then we here in the U.S. probably then would've had n-c.Sebring-models still being sold into the 70s as well, cuz those 1966 n-c.350-versions continued to be sold over-here through 1968, as it was (without that added batch).
So I'm unaware of what actual w-c.350 road-models Ducati had in production for the 1967 model-year (produced for other than the U.S.), as WE only received w-c.250/350Scrambler-models for that year.
" I have the best part of a very early 250 W/C scrambler rolling chassis.
It has a tank similar to the narrowcase scrambler and has no lower loops under where on a mark 3 the tool boxes are. The mudguards are also of different section to later scramblers. There is so little information about these bikes written so any info or knowledge you may have would be appreciated. Maybe I should use a narrowcase head "
____ That would probably do, as I do believe that those early w-c.250Scramler-models employed the same 250-head as was used on the 1966 n-c.250Scranbler-model.
__ I'm pretty familiar with those unique 1967 w-c.Scrambler-models, (and I even still own one), so I should be able to answer most any question you have about them. ...
The 250-version came with a unique to itself Scranbler-cam, and both the 250 & 350 came with an ignition-system virtually identical to the system employed on the 1966 250n-c.Scrambler.
" I meant 69mm, "
____ Have you ever heard any explanation as to why that 250Mototrans-model ended-up with a 69mm-bore ? _ (I believe I have the answer.)
Do you think that 69mm bore-size dictated the 66mm-stroke, or vice-versa ? - (In the case of the original 175, we KNOW that it was the (Dr.T-chosen) 62mm-bore which thus-then dictated the 57.8mm-stroke !)
" With the Spanish widecase heads I was reffering to the head diameter at the edge of the squish. Something tells me they are not 74mm & 76mm, just an element of doubt. "
____ I'm not positive but I have one of each (setting in boxes, currently unavailable to me) and don't recall anything out of the std.norm in that regard.
__ I have a related question for you Nigel, have you ever chanced upon any 350-heads without any squish-band & with combustion-chambers pretty-much shaped the same as 200-heads are ?
I ask because I have two examples of such (acquired many years apart), but assumed they were both likely re-machined so as to accept BSA.441-pistons (as ONE of those heads came to me with a basket-engine modded with such a piston).
" I have taken some pictures"
____ And nice shots they are Nigel, thanks for all those !
" If your head is as I described slab sided ( like a Desmo cap) then it will be Italian as I have never seen a Spanish head like this. "
____ I completely agree with that good conclusion !
" Some very Late Italian engines (75) had Spanish heads and other components, "
____ I was unaware of such (mix-mash).
____ It would be interesting & nice if we could have a few other w-c.350-owners post pictures of their cly.head's cap/cover-area, so as to get an idea of the ratio between the two types... It's been my-own experience that the DESMO-appearing version is the rarest type, (while evidently just the opposite where YOU've lived).
__ I've reposted a couple of Nigel's pix for easier direct-comparison between a DESMO-head & the later-type of springer-head which appears able to accept the same D.cap/cover.
Duke-Cheers,
-Bob
____ Well actually the early 350 w-c.heads were not the same as the n-c.Sebring-head...
The port-size is 29.5mm instead of 26.5mm, and they have the larger valve-seats. _ However I can't (now) confirm whether the squish-band is the same (width & angle) as the Sebring-head. _ But considering what you've pointed-out about the w-c.350-piston, I'd figure not.
" Not many Early widecases were sold here in the UK, as our market was flooded with much cheaper "grey imported" US rejected square style narrowcase models which were still being sold in the early 70's. "
____ Yes that big mess-up was a fiasco ! _ Berliner should've been FORCED to accept that rejected production-batch of n-c.Duke-models, even if they then had to sell them at no profit. _ But then we here in the U.S. probably then would've had n-c.Sebring-models still being sold into the 70s as well, cuz those 1966 n-c.350-versions continued to be sold over-here through 1968, as it was (without that added batch).
So I'm unaware of what actual w-c.350 road-models Ducati had in production for the 1967 model-year (produced for other than the U.S.), as WE only received w-c.250/350Scrambler-models for that year.
" I have the best part of a very early 250 W/C scrambler rolling chassis.
It has a tank similar to the narrowcase scrambler and has no lower loops under where on a mark 3 the tool boxes are. The mudguards are also of different section to later scramblers. There is so little information about these bikes written so any info or knowledge you may have would be appreciated. Maybe I should use a narrowcase head "
____ That would probably do, as I do believe that those early w-c.250Scramler-models employed the same 250-head as was used on the 1966 n-c.250Scranbler-model.
__ I'm pretty familiar with those unique 1967 w-c.Scrambler-models, (and I even still own one), so I should be able to answer most any question you have about them. ...
The 250-version came with a unique to itself Scranbler-cam, and both the 250 & 350 came with an ignition-system virtually identical to the system employed on the 1966 250n-c.Scrambler.
" I meant 69mm, "
____ Have you ever heard any explanation as to why that 250Mototrans-model ended-up with a 69mm-bore ? _ (I believe I have the answer.)
Do you think that 69mm bore-size dictated the 66mm-stroke, or vice-versa ? - (In the case of the original 175, we KNOW that it was the (Dr.T-chosen) 62mm-bore which thus-then dictated the 57.8mm-stroke !)
" With the Spanish widecase heads I was reffering to the head diameter at the edge of the squish. Something tells me they are not 74mm & 76mm, just an element of doubt. "
____ I'm not positive but I have one of each (setting in boxes, currently unavailable to me) and don't recall anything out of the std.norm in that regard.
__ I have a related question for you Nigel, have you ever chanced upon any 350-heads without any squish-band & with combustion-chambers pretty-much shaped the same as 200-heads are ?
I ask because I have two examples of such (acquired many years apart), but assumed they were both likely re-machined so as to accept BSA.441-pistons (as ONE of those heads came to me with a basket-engine modded with such a piston).
" I have taken some pictures"
____ And nice shots they are Nigel, thanks for all those !
" If your head is as I described slab sided ( like a Desmo cap) then it will be Italian as I have never seen a Spanish head like this. "
____ I completely agree with that good conclusion !
" Some very Late Italian engines (75) had Spanish heads and other components, "
____ I was unaware of such (mix-mash).
____ It would be interesting & nice if we could have a few other w-c.350-owners post pictures of their cly.head's cap/cover-area, so as to get an idea of the ratio between the two types... It's been my-own experience that the DESMO-appearing version is the rarest type, (while evidently just the opposite where YOU've lived).
__ I've reposted a couple of Nigel's pix for easier direct-comparison between a DESMO-head & the later-type of springer-head which appears able to accept the same D.cap/cover.
Duke-Cheers,
-Bob
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PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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LaceyDucati
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Re: wanted 350 widecase head
Bob
I am aware of most of the differences in port and valve sizes between different models like Sebrings and W/C 350 models. I'm only really discussing castings here, otherwise this thread is going to escalate somewhat! While on the subject of early W/C models I would presume the W/C Sebring would have the same head as a N/C Sebring complete with 26.5mm port etc. As we never had any W/C Sebrings and I have never even seen or heard of anyone having one it's another unknown are for me.
I'm glad those square style N/C bikes did flood the UK market as they did start a lot of people off with Ducati's. Firstly they were affordable compared to the new W/C models and secondly they formed the basis of so many Clubman race bikes. The clubman race bikes have left a lasting legacy in the racing fraternity that still continues today. I have an Original Square style Sebring which I am going to restore to original, feels like the right thing to do as there are so few original bikes left now (at least in the UK). Sort of a homage to the bike and maybe a penance for my part in it's demise!
I will come back to you for more specific info on the early scrambler some later time.
Not come across any full Hemi 250/350 heads which I thought were original, never heard of anyone claiming otherwise either.
The 66mm stroke was almost certainly a result of the 69mm bore. The spanish 250 N/C is based on the 200 and 69mm represents the largest practical bore size for a 200 barrel without moving the head bolts. The 250 barrel is the same casting (pre machining) as the 200 as are the crankcases, therefore give or take a few machining changes there was little re tooling required to bring out a 250 model. They then later did there own 5 speed conversion, similar to the Italian models (but not wholly the same) and they continued with this 69x66 set up until they went over to W/C.
I have just had a rummage and found a 350 W/C Spanish head and it measures 74mm. So probably all the early W/C Spanish 250/350 heads were the same in this respect as Italian W/C models. But I Still have a nagging doubt about some of those later 70's and 80's bikes, as I am sure I have measured 75, 76 or 77 across the head and it was definitely factory.
Regards Nigel
I am aware of most of the differences in port and valve sizes between different models like Sebrings and W/C 350 models. I'm only really discussing castings here, otherwise this thread is going to escalate somewhat! While on the subject of early W/C models I would presume the W/C Sebring would have the same head as a N/C Sebring complete with 26.5mm port etc. As we never had any W/C Sebrings and I have never even seen or heard of anyone having one it's another unknown are for me.
I'm glad those square style N/C bikes did flood the UK market as they did start a lot of people off with Ducati's. Firstly they were affordable compared to the new W/C models and secondly they formed the basis of so many Clubman race bikes. The clubman race bikes have left a lasting legacy in the racing fraternity that still continues today. I have an Original Square style Sebring which I am going to restore to original, feels like the right thing to do as there are so few original bikes left now (at least in the UK). Sort of a homage to the bike and maybe a penance for my part in it's demise!
I will come back to you for more specific info on the early scrambler some later time.
Not come across any full Hemi 250/350 heads which I thought were original, never heard of anyone claiming otherwise either.
The 66mm stroke was almost certainly a result of the 69mm bore. The spanish 250 N/C is based on the 200 and 69mm represents the largest practical bore size for a 200 barrel without moving the head bolts. The 250 barrel is the same casting (pre machining) as the 200 as are the crankcases, therefore give or take a few machining changes there was little re tooling required to bring out a 250 model. They then later did there own 5 speed conversion, similar to the Italian models (but not wholly the same) and they continued with this 69x66 set up until they went over to W/C.
I have just had a rummage and found a 350 W/C Spanish head and it measures 74mm. So probably all the early W/C Spanish 250/350 heads were the same in this respect as Italian W/C models. But I Still have a nagging doubt about some of those later 70's and 80's bikes, as I am sure I have measured 75, 76 or 77 across the head and it was definitely factory.
Regards Nigel
Last edited by LaceyDucati on Fri Feb 01, 2013 2:44 pm, edited 1 time in total.
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DewCatTea-Bob
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Variances of 250/350 Cylinder-heads
" I am aware of most of the differences in port and valve sizes between different models like Sebrings and W/C 350 models. I'm only really discussing castings here, "
____ While I never bothered go-over the earliest w-c.350-head with a fine-tooth comb & magnifier (to check for any further differences), I don't recall ever noting any obvious difference at-all other than that which I've mentioned,, so concerning the CASTing-MODEL itself, I've always assumed it to be (externally) the same as a n-c.Sebring-head, (but the door must be left open on that, in-light of your revealed detail-knowledge).
\
" While on the subject of early W/C models I would presume the W/C Sebring would have the same head as a N/C Sebring complete with 26.5mm port etc. As we never had any W/C Sebrings and I have never even seen or heard of anyone having one it's another unknown are for me. "
____ Yeah, it's a darn-shame that such Duke-models didn't sell better ! - (I personally hold the D.factory.workers' union responsible for that [due to their inflated wage demands].)
__ None the less, w-c.Sebring-models were definitely produced (for at least one production-run), as not only did I see pix of them in cycle-mags back-then, but also apparently Canada got a batch of them (back sometime between 1967 & 70).
Back when I was a Tech.adviser for the DIOC, a fellow-member in Canada mailed me a photo of his and he was surprised to learn that the U.S. didn't also have such w-c.Monza & Sebring-models.
While they did indeed employ the same 24mm-Del.carb, I don't personally know anything about the particular cyl.head employed other than that it had a unique w-c.version of the Violet-Monza/Sebring-cam (which is slightly MILDer than the n-c.version). _ And also, I've had a 6 or 8 page w-c.update-supplement issued to be added together with the standard 1966 owner's-manual (for purchasers of the w-c.Monza/Sebring models),, of which amongst other differing/updated-details, it includs the updated cam.valve-timing & lift specs).
__ If there are any Canadian members (registered here at this w.site) who have either a w-c.model Sebring or Monza, PLEASE post a picture or at-least mention if you actually have an example of such a w-c.model !
" Not come across any full Hemi 250/350 heads which I thought were original, never heard of anyone claiming otherwise either. "
____ Of-course I had great-doubt that you might've ever chanced-upon any factory-produced 250/350 hemi-heads,, but considering that you're in the Land of (old) BSA-models, I thus thought that perhaps the blending of such model/makes may likely be more prevalent over-there.
" The 66mm stroke was almost certainly a result of the 69mm bore. The spanish 250 N/C is based on the 200 and 69mm represents the largest practical bore size for a 200 barrel without moving the head bolts. The 250 barrel is the same casting (pre machining) as the 200 as are the crankcases, therefore give or take a few machining changes there was little re tooling required to bring out a 250 model. They then later did there own 5 speed conversion, similar to the Italian models (but not wholly the same) and they continued with this 69x66 set up until they went over to W/C. "
____ How very interesting ! _ I sure wish that such additional genealogical motor production-line evolution had made it over-here into the U.S. as well ! _ But rather during a more sensible time-period when it would've then naturally fallen-into the normal progression of Duke-motor production-advancement, (say around 1960-62).
__ Anyhow, even though I had already once known of most all of this stuff, it's nice to have such rare-oddity confirmed as having actually existed.
Your provided explanation for the particular bore & stroke of the (rare) near-square B&S 250 is certainly quite good, and is very likely indeed the actual explanation for the resulting rather odd 69x66mm B&S.
However, what do you think is the justifying-cause for Mototrans to have bothered with producing such rather ground-breaking motor-parts combinations with obsolete designs, nearly a decade out-of-sink with the more modern forward-advancing production-progression ?
Cuz it seems that there had to have been some underlying motive to go such a route as they did !
I can understand an individual (like myself) wishing to create such oddity for the sake of coming-up with something truly unique, but it doesn't seem very sensible for a manufacturer to mass-produce such.
I had once heard-tale of that motor-model having been produced for motorist insurance-issue purposes, but I don't recall the underlying reasoning for it. _ Was it due to keeping it from producing over a certain amount of horse-power, or what exactly ?
__ Anyhow, if no-one else comes-up with any better explanation, I've previously figured that the reason for why Mototrans created such fairly uniquely-different motor-conceptions, had to do with licensing-agreements with Ducati, which happened to limit Mototrans to motor-designs which Ducati deemed to have become obsolete (in relation to what they-themselves were then still producing).
And the 66mm crankshaft was one of those examples, (due to the abandoned 300-engine).
So that's why I thought perhaps the 'stroke' of that strange 250-motor came BEFORE the odd 69mm bore-size.
" found a 350 W/C Spanish head and it measures 74mm. So probably all the early W/C Spanish 250/350 heads were the same in this respect as Italian W/C models. "
____ Well that now spares myself from having to do that added check on one of mine, but considering that the Mototrans-head is definitely different in other ways, I therefore still ought to go double-check an EARLY w-c Italian-made 350-head.
Dukaddy-DUKEs,
-Bob
____ While I never bothered go-over the earliest w-c.350-head with a fine-tooth comb & magnifier (to check for any further differences), I don't recall ever noting any obvious difference at-all other than that which I've mentioned,, so concerning the CASTing-MODEL itself, I've always assumed it to be (externally) the same as a n-c.Sebring-head, (but the door must be left open on that, in-light of your revealed detail-knowledge).
\
" While on the subject of early W/C models I would presume the W/C Sebring would have the same head as a N/C Sebring complete with 26.5mm port etc. As we never had any W/C Sebrings and I have never even seen or heard of anyone having one it's another unknown are for me. "
____ Yeah, it's a darn-shame that such Duke-models didn't sell better ! - (I personally hold the D.factory.workers' union responsible for that [due to their inflated wage demands].)
__ None the less, w-c.Sebring-models were definitely produced (for at least one production-run), as not only did I see pix of them in cycle-mags back-then, but also apparently Canada got a batch of them (back sometime between 1967 & 70).
Back when I was a Tech.adviser for the DIOC, a fellow-member in Canada mailed me a photo of his and he was surprised to learn that the U.S. didn't also have such w-c.Monza & Sebring-models.
While they did indeed employ the same 24mm-Del.carb, I don't personally know anything about the particular cyl.head employed other than that it had a unique w-c.version of the Violet-Monza/Sebring-cam (which is slightly MILDer than the n-c.version). _ And also, I've had a 6 or 8 page w-c.update-supplement issued to be added together with the standard 1966 owner's-manual (for purchasers of the w-c.Monza/Sebring models),, of which amongst other differing/updated-details, it includs the updated cam.valve-timing & lift specs).
__ If there are any Canadian members (registered here at this w.site) who have either a w-c.model Sebring or Monza, PLEASE post a picture or at-least mention if you actually have an example of such a w-c.model !
" Not come across any full Hemi 250/350 heads which I thought were original, never heard of anyone claiming otherwise either. "
____ Of-course I had great-doubt that you might've ever chanced-upon any factory-produced 250/350 hemi-heads,, but considering that you're in the Land of (old) BSA-models, I thus thought that perhaps the blending of such model/makes may likely be more prevalent over-there.
" The 66mm stroke was almost certainly a result of the 69mm bore. The spanish 250 N/C is based on the 200 and 69mm represents the largest practical bore size for a 200 barrel without moving the head bolts. The 250 barrel is the same casting (pre machining) as the 200 as are the crankcases, therefore give or take a few machining changes there was little re tooling required to bring out a 250 model. They then later did there own 5 speed conversion, similar to the Italian models (but not wholly the same) and they continued with this 69x66 set up until they went over to W/C. "
____ How very interesting ! _ I sure wish that such additional genealogical motor production-line evolution had made it over-here into the U.S. as well ! _ But rather during a more sensible time-period when it would've then naturally fallen-into the normal progression of Duke-motor production-advancement, (say around 1960-62).
__ Anyhow, even though I had already once known of most all of this stuff, it's nice to have such rare-oddity confirmed as having actually existed.
Your provided explanation for the particular bore & stroke of the (rare) near-square B&S 250 is certainly quite good, and is very likely indeed the actual explanation for the resulting rather odd 69x66mm B&S.
However, what do you think is the justifying-cause for Mototrans to have bothered with producing such rather ground-breaking motor-parts combinations with obsolete designs, nearly a decade out-of-sink with the more modern forward-advancing production-progression ?
Cuz it seems that there had to have been some underlying motive to go such a route as they did !
I can understand an individual (like myself) wishing to create such oddity for the sake of coming-up with something truly unique, but it doesn't seem very sensible for a manufacturer to mass-produce such.
I had once heard-tale of that motor-model having been produced for motorist insurance-issue purposes, but I don't recall the underlying reasoning for it. _ Was it due to keeping it from producing over a certain amount of horse-power, or what exactly ?
__ Anyhow, if no-one else comes-up with any better explanation, I've previously figured that the reason for why Mototrans created such fairly uniquely-different motor-conceptions, had to do with licensing-agreements with Ducati, which happened to limit Mototrans to motor-designs which Ducati deemed to have become obsolete (in relation to what they-themselves were then still producing).
And the 66mm crankshaft was one of those examples, (due to the abandoned 300-engine).
So that's why I thought perhaps the 'stroke' of that strange 250-motor came BEFORE the odd 69mm bore-size.
" found a 350 W/C Spanish head and it measures 74mm. So probably all the early W/C Spanish 250/350 heads were the same in this respect as Italian W/C models. "
____ Well that now spares myself from having to do that added check on one of mine, but considering that the Mototrans-head is definitely different in other ways, I therefore still ought to go double-check an EARLY w-c Italian-made 350-head.
Dukaddy-DUKEs,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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LaceyDucati
- Posts: 578
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- Location: Wales UK
- Contact:
Re: wanted 350 widecase head
Bob
I would agree with you about the "cooking" models like the sebring and monza and unfortunatly there are not enough left for people to appreciate them for what they are. I have a nice original 900GTS which I love for the same reasons.
There is a nice picture of a widecase Sebring in Ian Falloons standard catalog of Ducati Motorcycles, resplendent in a bright metallic green.
I did think about scanning and posting it, but this will probably result in the arrival of warnings and lawyers!
I had a look with an eye glass and unfortunately the picture is to grainy to identify the said head face. It does look like it could be slab sided!
Nigel
I would agree with you about the "cooking" models like the sebring and monza and unfortunatly there are not enough left for people to appreciate them for what they are. I have a nice original 900GTS which I love for the same reasons.
There is a nice picture of a widecase Sebring in Ian Falloons standard catalog of Ducati Motorcycles, resplendent in a bright metallic green.
I did think about scanning and posting it, but this will probably result in the arrival of warnings and lawyers!
I had a look with an eye glass and unfortunately the picture is to grainy to identify the said head face. It does look like it could be slab sided!
Nigel
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DewCatTea-Bob
- Posts: 2897
- Joined: Sun Nov 01, 2009 10:53 am
- Location: Near SE side of Lake Michigan
Variances of 250/350 Cylinder-heads
" There is a nice picture of a widecase Sebring in Ian Falloons standard catalog of Ducati Motorcycles, "
____ I don't own any books on DUKEs printed after the late-80s, so I wonder if that book mentions anything about how many of that rare model were produced !?
" the picture is to grainy to identify the said head face. It does look like it could be slab sided! "
____ I guess that would stand to fair reason actually, cuz once Ducati began producing the w-c.motor's engine-heads, they then also at that time began producing their camshafts with notably smaller base-circle diameters.
So if the w-c.Sebring had continued to use the exact-same cyl.head-model, then their would not have been any just-cause for having altered the particular camshaft from that of the n-c.version.
Dukaddy-DUKEs,
-Bob
____ I don't own any books on DUKEs printed after the late-80s, so I wonder if that book mentions anything about how many of that rare model were produced !?
" the picture is to grainy to identify the said head face. It does look like it could be slab sided! "
____ I guess that would stand to fair reason actually, cuz once Ducati began producing the w-c.motor's engine-heads, they then also at that time began producing their camshafts with notably smaller base-circle diameters.
So if the w-c.Sebring had continued to use the exact-same cyl.head-model, then their would not have been any just-cause for having altered the particular camshaft from that of the n-c.version.
Dukaddy-DUKEs,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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double diamond
- Posts: 557
- Joined: Thu Apr 28, 2011 1:20 am
Re: wanted 350 widecase head
Nigel, I have an early 250 W/C Scrambler (frame does not have the additional curved tube between motor mount and seat stay and as a consequence has the broken frame tube above the motor mount that led to this update). The engine that was installed has a head with the bearing cap profile like a desmo bearing cap. If this was the original engine, at least one early W/C scrambler came with this later head. This bike was flogged though so may not be original.
I’ve spoken with a very experienced Ducati expert here in California who has also commented on 250 heads with no squish band. I’ve seen some heads like this that were obviously (poorly) modified to remove the squish band (probably due to a piston/ring/valve failure that damaged the squish band) i.e. material removed wjth a die grinder to match a piston with a hemispherical profile. Obviously not factory issue. I suspected this when these heads were suggested. But this individual I’ve spoken with on the subject insists he’s disassembled previously untouched engines that had hemispherical combustion chambers with no squish band. With all the other undocumented Ducati specification differences I’ve come across, I’m inclined to believe some heads of this configuration may well exist.
Matt
I’ve spoken with a very experienced Ducati expert here in California who has also commented on 250 heads with no squish band. I’ve seen some heads like this that were obviously (poorly) modified to remove the squish band (probably due to a piston/ring/valve failure that damaged the squish band) i.e. material removed wjth a die grinder to match a piston with a hemispherical profile. Obviously not factory issue. I suspected this when these heads were suggested. But this individual I’ve spoken with on the subject insists he’s disassembled previously untouched engines that had hemispherical combustion chambers with no squish band. With all the other undocumented Ducati specification differences I’ve come across, I’m inclined to believe some heads of this configuration may well exist.
Matt
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DewCatTea-Bob
- Posts: 2897
- Joined: Sun Nov 01, 2009 10:53 am
- Location: Near SE side of Lake Michigan
Variances of 250/350 Cylinder-heads
" I have an early 250 W/C Scrambler (frame does not have the additional curved tube between motor mount and seat stay and as a consequence has the broken frame tube above the motor mount that led to this update). The engine that was installed has a head with the bearing cap profile like a desmo bearing cap. If this was the original engine, at least one early W/C scrambler came with this later head. This bike was flogged though so may not be original. "
____ That must indeed be a 1967 w-c.Scrambler but, at least the head must not be stock because they didn't cast cyl.heads that way before the DESMO-heads were produced for 1968.
__ To help determine if the motor's bottom-end is stock, check to see if it's alt.cable contains THREE alt.stator wire-leads,, or just the standard pair of yellow wire-leads (as employed starting early-68).
" I’ve spoken with a very experienced Ducati expert here in California who has also commented on 250 heads with no squish band. I’ve seen some heads like this that were obviously (poorly) modified to remove the squish band "
____ In some localities across the U.S., I guess such work was somewhat commonly done so as to fit a 79mm BSA441-piston into a 350-engine,, but I've never been aware of anything of the sort being done for a 250-engine, (as the 250 cyl.liner is not wide & thick enough).
" But this individual I’ve spoken with on the subject insists he’s disassembled previously untouched engines that had hemispherical combustion chambers with no squish band. "
____ I really don't think that Ducati-themselves bothered to produce any cyl.heads without squish-bands after 1962, but it's of-course likely that old Duke-fella did indeed encounter such with all 200-engines he disassembled !
__ This leads to the question of whether the odd-250 with the 69x66mm-B&S had a squish-band or not !?
Dukaddy-DUKEs.
DCT-Bob
____ That must indeed be a 1967 w-c.Scrambler but, at least the head must not be stock because they didn't cast cyl.heads that way before the DESMO-heads were produced for 1968.
__ To help determine if the motor's bottom-end is stock, check to see if it's alt.cable contains THREE alt.stator wire-leads,, or just the standard pair of yellow wire-leads (as employed starting early-68).
" I’ve spoken with a very experienced Ducati expert here in California who has also commented on 250 heads with no squish band. I’ve seen some heads like this that were obviously (poorly) modified to remove the squish band "
____ In some localities across the U.S., I guess such work was somewhat commonly done so as to fit a 79mm BSA441-piston into a 350-engine,, but I've never been aware of anything of the sort being done for a 250-engine, (as the 250 cyl.liner is not wide & thick enough).
" But this individual I’ve spoken with on the subject insists he’s disassembled previously untouched engines that had hemispherical combustion chambers with no squish band. "
____ I really don't think that Ducati-themselves bothered to produce any cyl.heads without squish-bands after 1962, but it's of-course likely that old Duke-fella did indeed encounter such with all 200-engines he disassembled !
__ This leads to the question of whether the odd-250 with the 69x66mm-B&S had a squish-band or not !?
Dukaddy-DUKEs.
DCT-Bob
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PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
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