Dellorto SSI 27 or 29 question

[mark3kb]

Hello, to all the Duc single enthusiasts . This is my first post and I hope you guys can help me out with this one. I would like to figure out two things regarding my late model year 64 Mark 3 250. First, if the 65 (which I believe my bike is, even though my Mark 3 title claimed 64) is supposed to come with a 27mm Dellorto spec carb,as Mick Walker states,why does the head have a Mach1/29mm port ? Could he have a typo on the carb spec page ?
Second, Does anyone know if the late model 64 or 65 Mark 3 came with a 150mph mile speedo? Mine has a 100 mph speedo and I would like to know if the 150 mph speedo began with the engine stamping designation DM250 M3. thanks mark3kb

[DewCatTea-Bob]

[quote= mark3kb ...
" I would like to figure out two things regarding my late model year 64 Mark 3 250. "

____ Pre-1965 Mark-three models ought be referred-to as a 'Mark III' Diana-model. _ (It wasn't until the 1965 model-year when the Diana-Mk3 model-line then had the Mach-I top-end adopted to it, that it then more officially got the slight name-change (from Mark-III) to 'Mark 3'.



" First, if the 65 (which I believe my bike is, even though my Mark 3 title claimed 64) "

____ If your titled-64 Mark-III is a version which was intended for the USA.market, then it more likely could be a 1963-model (rather than a "65") ! _ As quite regularly done back-then,, Dukes were often titled the year when they finally sold to the first retail-owner, rather than the actual year of manufacture by the factory.
So your Duke's motor-number would help determine the particular model-year of your Mark-III model.



" is supposed to come with a 27mm Dellorto spec carb,
why does the head have a Mach1/29mm port ? "

____ There's never been any 250-cyl.head specifically with exactly a "29mm port"... rather than 29.0mm, Mark-three cyl.heads had intake-ports of either 28.5 (for the M.III) or 29.5mm (for the M.3). - (The '.5' actually varies .1mm.)
So you need to take a more accurate reading of the in.port's actual diameter.



" Could he have a typo on the carb spec page ? "

____ I-myself don't have a copy of the Mick Walker book, but his stated-specs would accordingly depend-on whether they concern made for USA.models actually produced in 1964 and-yet sold in early-1965 (as very-many Mark-III versions were !),, as all 'Mark-III' models originally came stock with the 27mm-SSI carb !
However, starting for the actual 1965 model-year,, factory-production by within THAT-year, had switched-over to the newer (& better !) 'Mark 3' version (with the 29mm-SSI [just like the 'Mach I' also employed], once the Mach-I had first gone into production for the 1965 model-year).



" Does anyone know if the late model 64 or 65 Mark 3 came with a 150mph mile speedo? "

____ I didn't yet work at any Ducati-shop back-then, so I don't really know FOR-SURE,, but I believe the 150MPH-speedo wasn't std.issue until 1965. _ (Wish we had at-least one older member with us [who owned a Ducat-shop back-then], who could confirm this issue for us.)



" Mine has a 100 mph speedo and I would like to know if the 150 mph speedo began with the engine stamping designation DM250 M3. "

____ I don't really KNOW for-sure,, however your logical-reasoning seems very quite-likely to me, and I know-of no exceptions to that plausible-reasoning.
I do have Ducati -singles parts-books which I could double-check on that, if you wish.


Duke-Cheers,
DCT-Bob

[mark3kb]

Hello Bob, thanks so much for all the information. I put together a bit more info for you to try to help with an identification.Its a super nice example, correct DM250M3 stamping, all correct frame details are present, tabs for rear sets if one were to install them (brake light switch and rear brake cable tabs present)rearset lugs as well, so I believe it is an original MIII frame as well as engine.I did check the head again and it is 28.6mm like you said with the .1mm differential.
Is it possible to have the 28.5mm head port (not 29.5mm) and still have the toolboxes for the 64 model year like my bike has.?This is a bit confusing because if my bike is late production 64,meaning a 65, ( I read in Mick Walkers book that the toolboxes first became available on the 65 model) it should have a 29.5mm head port(meaning larger valve head as well) along with the toolboxes like the Mach 1 did for that year.I am wondering if the late production model mixed the toolboxes with the smaller 28.5mm head on the final Mark III. Confusing but getting clearer!

The engine # is 95043
Head has clothes pin type spring with shim ( I checked)
There is no switch at the rear tail light (for the goofy if the bulb fails scenario)
It has the tank cutout for the larger SSI carb with the correct Mark 3 tank.
Thats all the information I have. i will post pics when I get the chance
Carb has been changed to 30mm UHB (missing 27 SSI)

[DewCatTea-Bob]

[quote= mark3kb ...
" thanks so much for all the information. "

____ Of-course, you're welcome !
____ Sorry for this delayed response, (seems I had overlooked noticing that you had updated this thread)...
I had gotten-use to this thread having been moved-down lower on the thread-list (due-to lack of activity), and didn't happen to see the thread-list during the short-period when this-thread must've been moved-up to the top,, and when I next saw the list, by then this-thread had already gotten pushed back-down to where it was before again, so I had just assumed that it was still unchanged (until I now noticed otherwise).



" I put together a bit more info for you to try to help with an identification. "

____ From what added info you've now posted, all the details given so-far are-not adding-up as they should ! _ So it's no-wonder that you've had to ask for help.



" Its a super nice example, correct DM250M3 stamping, all correct frame details are present, tabs for rear sets
rearset lugs as well, so I believe it is an original MIII frame as well as engine. "

____ WELL, everything is actually-NOT so "correct" , (as you ought-to have suspected from that info which I've already posted) ! ...
__ First of all, the 'M3' motor-number stamping is of-course NOT something to be expected on a Mark III model, (as that M3-stamping didn't exist until the time when the M1-stamping began for the 1965 Mach-I) !
And also,, the other details you've included about the frame, ALSO indicate a 'Mark-3', (as I don't believe that any pre-65/Mark-III Mark-three model came stock with those particular frame-pieces).
So it's quite understandable why you had figured that your Duke is a "1965" model (rather than a '64) !



" I did check the head again and it is 28.6mm like you said with the .1mm differential. "

____ THAT however, is INCONSISTENT with an actual 1965-model !



" Is it possible to have the 28.5mm head port (not 29.5mm) and still have the toolboxes for the 64 model year like my bike has.? "

____ These-days anything is possible, but back in 1964 those two identification-details were-not to be found originally matched-together.
The side-cover/toolboxes are only consistent with the n-c.Mark-3 models of 1965 thru 1967.
If you are quite sure that the intake-port is-not larger than 29mm, then the cyl.head is-not a 1965 Mk3.head.



" This is a bit confusing because if my bike is late production 64,meaning a 65, "

____ Your "bike" can-NOT be a "64", (but it's cyl.head might possibly be of some other year).



" ( I read in Mick Walkers book that the toolboxes first became available on the 65 model) "

____ I believe that to be TRUE, as I've never seen any Mark-III with tool-boxes, (ONLY on the 'Mark-3' models, however) !



" it should have a 29.5mm head port(meaning larger valve head as well) along with the toolboxes "

____ Right, your 1965-Duke's M3.engine SHOULD-have the large-valve cyl.head with the larger in.port !
(But there's a likely reason for why it seems to have a non-stock head.)



" I am wondering if the late production model mixed the toolboxes with the smaller 28.5mm head on the final Mark III. "

____ As I unfortunately didn't work on the production-lines, I can't be sure that such mix-up/matching didn't happen to occur but, I'm fairly-sure that no such unique 'Mark-3' model-parts were ever matched-up together with a cyl.head having the smaller Mark-III type intake-port (by the FACTORY).
__ The MOST-likely reason for why your cyl.head doesn't match-up with the REST of your Mark-3 Duke-model, is probably because it was a victim of a rather common performance-parts snatcher, (like I-myself once was),, as 250M3-heads were often robbed for employment on project race-bikes ! _ Then after the M3.head-robbery/swap was done, the robbed M3.Duke was then sold-off (possibly as still stock) to help finance the intended project-racer.
If this fairly-common scenario-occurrence does happen to be the case with yours,, then you can bet that your cyl.head isn't even a (less desirable) Mark-III model, and is no-doubt really an even-less desirable Scrambler-head (with it's rather mild camshaft).
__ This mystery-head situation ought-to be checked-into further !
Do you want to get-to-the-bottom of which actual cyl.head-model you really have ?



" The engine # is 95043 "

____ GOOD-news is, that motor-number is totally consistent with an ACTUAL 1965 Mark-3 model !!



" Head has clothes pin type spring with shim "

____ That's consistent with ANY non-Monza/GT-type cyl.head.



" There is no switch at the rear tail light "

____ Then it could be that your M3.Duke's entire electrical-system has been redone.



" Carb has been changed
(missing 27 SSI) "

____ Then it's really missing a 29mm SSI !


Hopeful-Cheers,
-Bob

[mark3kb]

Well, thanks again DCT Bob, that is a lot of info and it now becomes clear as to what year a bike I really own. I do believe what I have is a 1965,which has had the head carb and 150mph speedo robbed as you suspect.All the other bits and pieces are the correct match for the year.
Frame has all lugs
Tank has large cutout for 29mm carb
Correct headlight shell with no other switches ,lights or fittings(just speedo)
Correct narrow fenders
paperwork numbers match
etc
The only other possibility is that the bike was constructed from a correct frame and engine with matching paperwork and all the other parts were put together to create a complete machine.
I wonder if the 65 model sales year in U.S.,could have been delivered to the U.S with 64 production paperwork?
I would also like to find out if the head I have is intact a Mark III head (hotter cam) or scrambler head (mild).I would guess, by the cam colour only because we already know that the valves will be 36,33.
Bob, you have been super helpful with this,and I have really enjoyed trying to figure this out, I think this will be the last step,hopefully! mark3kb Kurt

[DewCatTea-Bob]

[quote= mark3kb ...
" carb and 150mph speedo robbed "

____ I-myself don't think the 150-speedo is something worth robbing, as they were a sales-gimmick which had next to no functional use cuz they were very useless for determining actual speed. _ And-so they were often considered faulty and-thus replaced with the (slightly better) type of unit which I gather you now have.



" I wonder if the 65 model sales year in U.S.,could have been delivered to the U.S with 64 production paperwork? "

____ Not at all likely, as Berliner went to extraordinary measures to allow pretty-much just the opposite of such, (such as by using frame-neck stickers with the final year digit left blank so that the actual year of manufacturer could be (shadily) obscured.
And also, your motor-number is somewhere less than a thousand units before the 1966 model-year (and more like 5k-units after the end of the 1964 model-year).



" I would also like to find out if the head I have is intact a Mark III head (hotter cam) or scrambler head (mild).I would guess, by the cam colour only "

____ It's quite doubtful that the dab of paint color-code is still visible on the threaded-end of the camshaft. _ So you'd have to remove the '250' cam-bearing support/cover and have a view at the cam.profile, (as the Mark-three cams are rather easy to tell-apart from the milder cams).
__ To (rather carefully !) remove that left-side cam.cover,, after removing it's four Allen-screws, then a thin/long shaft-pin should fit through the hole in the center of the camshaft (from the right-side), and light taping on that pin should then dislodge the cover/support (out of it's normal-place) until it's become knocked-outward only about 15mm, at which point that piece can then be grabbed by hand & twisted-out the rest of the way away-from it's place in the head.
__ If you take a well lite picture of the (then visible) ex.cam-lobe profile (and post it), I can then no-doubt identify the camshaft-model for you.



" I have really enjoyed trying to figure this out, "

____ Then we've BOTH done so !


Duke-Cheers,
-Bob

[mark3kb]

Hi Bob, here is a well lit pic of the cam profile, thanks mark3kb

[Eldert]

Hi Mark

the camshaft looks like a scrambler cam to me ( colorcode White )

Eldert

[DewCatTea-Bob]

[quote= mark3kb ...
" here is a well lit pic of the cam profile, "

____ Indeed so, and done fairly competently as well -(pic.shot well lined-up !) !
____ Well you've already been alerted as to what to likely expect from me concerning the verdict on your cam.model, (so-thus I won't be letting you down as hard, all at once),, since Eldert has already posted his-own good opinion !
It's nice that someone besides myself has chimed-in of this, (especially Eldert),, cuz now you don't have to take merely-just my-own word on it. ...
__ While it's possible that the pictured cam could possibly be a 250-Monza cam.model,, considering the model of cyl.head it's in, it's fairly more-likely to be a Scrambler-cam (of the n-c.type variety) !
So I'm sorry to report that not only is that cam not a Mark-three type, there's no-chance of it being anything other than a Monza/Scrambler-type cam.grind.
__ So you now KNOW that the stock Mark-3 cyl.head was swapped-out for a n-c.Scrambler-head !
While the Scrambler-head is-not as high-performance as that of a M3.model, it's really not such a 'mild' combination of cyl.head-parts either, (as compared to a GT or even a Monza cyl.head-setup) ! _ As low-end power is a bit stronger and mid-range is about the same as that of a Mark-three engine.
If the piston is still the stock Mark-3 unit, then you should find that the engine is extra difficult to kick-over, (due-to the increased compression with the milder cam).
So, your 250-engine still ought-to make respectable power.


Dukaddy-DUKEs,
-Bob

[Cam3512]

Hi Bob, here is a well lit pic of the cam profile, thanks mark3kb

Not to hijack the thread, but is there a trick to removing the cam cover? I removed the four bolts to change out the gasket, but the cover wouldn't budge.

Cam