Camshaft Data

[Eldert]

Hi Frank

the timing side cases are interchangable between NC and WC engines .
but you have to check the clearance between the bronze bushing and crankshaft end when swapping things

another option would be to buy some new oil pump gears if your housing is OK



i have a couple of NOS sets laying around . i would like to get 30 US dollar for a set . this includes the shipping

Eldert

[DewCatTea-Bob]

" You are also correct in that the rocker faces are slightly concave where they meet the cam. "

____ Then it could be that the rockers & camshaft are all the original-parts thus have been wearing together ever since the oil-pump quit. _ But, with all the excessive-wear (over 2mm) on the cam, I certainly would not expect the use of the word "slightly" to be used in regards to the rocker-arm wear ! _ With the cam worn that bad, you then should've found a wavy -(dual-like) concaved wear-area with at least 2mm gone/taken-out from the cam-follower's surface-radius !
__ And when you removed the valve-covers, you must have then noticed the extreme valve&rocker clearance. _ It's too bad that you did not have another running DUKE so you'd more quickly realize that the sounds of your motor were not normal, and then investigate sooner before so much wear occurred !


" The lack of oil circulation seems to have affected the top end more than the bottom.
I haven't split the cases but the play at the big end of the crank seems ok. "

____ When the oil-pump stops, the TOP-end then gets extra very hot and more quickly begins to go-bad, compared to the rest of the engine (I stated "engine" not 'motor', because the transmission is not fed oil-pumped lube!) _ So HOPEfully all your bottom-end engine-parts are still good to go. _ (As is usually the case when the oil-pump has been found out of service.)
__ While it's true that all those engine-parts (which depended on oil, and yet are still usable), are now the-worse-for-wear,, this simply means that a COMPLETE-rebuild is to be expected somewhat sooner than normal, and NOT that you NEED to do it now. _ As those parts which are not worn well beyond factory-specs, will still last for a very worth-while amount of time.


" Everything will have to be inspected to determine whether it will be worth saving. "

____ Aside from the cam & rockers, the two camshaft support-bearings & upper tower-shaft bearing may be found to need replacement.
Whenever I've run into this particular break-down, usually little other than the cam & rockers were ever in need of replacement, since the problem is most often found soon after the engine starts making the new noises. _ Of the 7 or 8 times when I've dealt with such a busted oil-pump break-down, only once was a complete-rebuild then inspired afterwords. _ So I'm betting that you can get your DUKE back up & running relatively cheaply.

____ Of worthy note, most every time I've found an oil-pump with a busted shaft-tip, I then also found within the pump a piece or two of metal-flaked debris which had somehow gotten wedged between the pump-gear(s) & housing.
__ I also found that in ever case, the oil-filter/screen tube was warped ! _ And thus probably was not fitted correctly with it's nose-tip properly sunk into it's receptacle-hole (which leads to the pump's oil-intake). - (A poor-design problem [for the average-owner who changes oil] that was made even more likely to occur with the wide-case motor [which uses an even longer screen-tube].)
__ So look to see if your oil-filter screen-tube shows any sign of having been warped some time in the past, as it was likely during that time when the debris got into your pump. _ (About half the times when I found a busted pump, it was within a couple-hundred miles after an oil-change had been done by the owner.)
So all of us should be extra careful when reinstalling the filter-tube, making sure that ya don't feel any building-resistance after a point when the plug/tube is threaded almost half-way inward (which is the same point when it's tip-end reaches the edge of it's receptor-hole) ! _ And if ya do feel the tube's tip-end miss it's home-spot (& thus begin building resistance), then just back-off a very slight bit, and ya should then FEEL it pop-into place, and can then safely continue screwing it back-in fully, without any further resistance (to being screwed-in the rest of the way) ! - (The unexpected "resistance" is actually the screen-tube getting warped! _ And will unwarp if not left in that squeezed-condition for very long.)
__ And if ya care about your DUKE like I do, it's always a good-idea to get down & look inside through the drain-hole with a flashlight, to make sure that there's nothing at all inside there to possibly get in the way and get pushed into the oil inlet-hole !
In fact, whenever I have the top-end off,, I use a small plastic-bottle -(for hair-coloring) filled with oil, with a snout-nozzle which gets it's tip stuck into the oil-passage at the top of the left-side motor-case, and then squeeze some oil in-through while rotating the crankshaft backward,, so as to back-flush the pump & oil-passage,
all before reinstalling the oil-plug/tube!
Any cycle/bike-mechanic who would not consider doing these added (anti-negligence) operations (whenever possible), is not a true DUKE-mechanic, as far as I'm concerned !


DUKE-Cheers,
DCT-Bob

[frankfast]

Eldert - Thank you for the offer. It is very reasonable. A very good friend of mine seems to think he may have a spare gear or pump in a bunch of spares in his basement. If not I most certainly will be in touch.

Bob - A friend of mine, who is also familiar with bevel-drives, thinks that with the amount of wear indicated at the cam, there might be problems with the big end rollers. He's convinced me to split the cases and separate the crank since the big end is also fed by the pump. I have had the bike for a long time although it ran very little. When it did run I hadn't noticed any noises that indicated a problem. You would think that with the condition of the cam and rockers the bike would sound awful. It didn't and ran quite well. I did a valve adjustment and don't remember that the clearances were off that much but maybe someone else had done an adjustment before I got the bike. Anyway it seems I have to start from the bottom to assess the damage and decide if it is worth it.

[DewCatTea-Bob]

" there might be problems with the big end rollers. He's convinced me to split the cases and separate the crank since the big end is also fed by the pump. "

____ If your motor bottom-end is still in the bike, then I advise against bothering to split the cases unless you're currently okay with having it end-up as a permanent basket-case.
I say this because many DUKE-owners take their motors apart with good-intention to fix all that needs to be brought-up to spec, but often end-up running-into various issues which then end-up causing the entire DUKE to never get back on the road again (and all it's bits & pieces eventually sold-off on eBay). _ (This is one reason why I think most every DUKE should have a spare/back-up motor!)
__ And on top of that reasoning.....
Since you've already found that the con.rod is still tight (which stands to reason, given it's low-mileage by you and the type of rod-bearing that went without oil), then it seems that all that extra work your friend wants ya to do is uncalled for, just to confirm that it was still all good ! _ As I've gone through DUKE-motors that were run with their oil-level so low that the rod's big-end seized-up, and yet with no other damage that NEEDED to be replaced.
So I think you should just fix the pump & cyl.head parts and ride your DUKE for the summer, (& probably next-summer as well) and postpone any more-thorough work to become a winter-project for some future year.
Unless of course your friend has all the parts you might need and will soon complete all the work for you for next to nothing, so that you can still have the same amount of remaining riding-season,, THEN that's just as well !


" When it did run I hadn't noticed any noises that indicated a problem.
I did a valve adjustment and don't remember that the clearances were off that much but maybe someone else had done an adjustment before "

____ That has indeed got to be the case then, cuz not only would the top-end have been noticeably noisy but you would've also had to have noticed the resulted 5mm of valve-clearance slop as well, besides !!
__ Now even more than before, I'm convinced that not only did a previous-owner have the excessive valve-clearances reset (before you got it), but also must've had replaced the very excessively-worn rocker-arms as well ! _ Two reasons for this conclusion...
First, in order for the cam to suffer about 2.5mm of wear, the rockers would then have been worn-down at least the same amount and look much considerably worse than that which you've conveyed to be the case.
And second, the previous owner would not have been able to find (Ducati-made) valve-stem shim-caps which were thick enough to properly fill the over 5mm clearance-gap! - (Unless perhaps the valve-seats had been previously ground-down thinner than their std.limits).
__ I have above average experience with the continued use of combinations of worn rocker-faces & cams, due to DUKE-owners of the past who didn't much care to spend the money on what to them was just a cycle -('bike'). _ So I happen to KNOW for myself that a DUKE can continue to run just fine-enough with a really-bad cam (even worse than yours!) OR with fairly-worn rockers,, just as you've now yourself come to realize !
__ When a fairly scored cam is used with new-rockers, the rockers will then only develop light scoring, (providing good oil is maintained). _ So in this case, it seems that the rocker-arms must have been replaced sometime while the oil-pump was still out of service. _ And thus without oil, the replacement-rockers have since also gotten worn-down.
__ If you were to choose to just fix your oil-pump only, then with the valve-clearances set, you could then sooner get back to riding your DUKE for the rest of the season,, just as many past uncaring Ducati-owners (who were actually just mere bike-owners) of the '70s had done & got away with.
Of course I'm not saying that that's the right-thing-to-do but, it works & will get you by for the rest of the season ! _ And likely without further consequence, if you keep your oil good.
I am saying however, that since the riding-season is currently upon us,, it makes better sense to leave the more extensive (and unnecessary) work for the winter-time.

____ Concerning worn rocker-arm faces,, back in the '70s there used to be a place in Washington (or Oregon?) who rebuilds DUKE rocker-arms, supposedly better than stock. _ And not only would they REFACE the cam-follower surface (with superior plating) to the stock 32mm-radius, they also allowed ya to choose a different radius of at least up to 4" (about 102mm).
Badly worn rockers were more expensive to reface back to the original radius, so if one wanted to much increase the radius, then that would be a good time to provide worn-rockers for the job !
__ Why would ya want to increase the radius of the cam-follower face,
ya may wonder?
Well that's another trick to increase performance, very much like increasing the cam-lobe's profile does ! _ The outcome does NOT increase the 'Actual' (or peak) valve-lift (as many others assume), but it does increase the 'average-lift', as well as the valve-timing's duration !! _ Which (for example) would be quite beneficial for a 350-Sebring that's retaining it's stock mild (Monza) cam.
__ I was once told by an engineer who was associated with that shop, that the DUKE-rockers had a safe radius limit of up to 4-inches and that they had redone many pairs with that radius, for both bevel singles & twins.
I myself would not recommend anything past a 96mm-radius for the milder DUKE-cams, and recommend no higher than a 64mm-radius for any DUKE-cam that's wilder than the Grey/M1-cam.
Also, I sure would not pay to have a pair done without having them redone to at least a 48mm-radius. _ And if I had two pairs redone, I would not choose to have both pairs redone to the same chosen radius.
If anyone knows who still does this work, please let us know !


DUKE-Cheers,
DCT-Bob

[frankfast]

I agree that the engine should not be split at this time. I'll take my chances and replace the pump, rockers, cam and guides (maybe top end bearings). It's amazing to me that the bike would run under the stress that it was under, although I have no idea when the pump ceased to work. Given the wear at the top, I don't know how long it would take to wear down a cam lobe over 2.5mm. Maybe not very long at all.
I also would like to know anyone who resurfaces rockers. These kinds of services seem to be dying in a disposable society. It's also a problem for me to spend the kind of money being asked in order to replace the needed parts. I have three bigger bikes (two belt drive Ducatis) that are ridden more and therefore are a priority. I've been messing around with beveldrives since the mid-seventies (I've owned two greenframes) and I've usually been able to source parts at reasonable prices through channels or a circle of Ducati people. Swapping was big back then and if you raced (as I did) there were always people who would help keep you on the track. Today parts for these bikes are viewed as gold and dealers know nothing about them (nor do they want to). They are used to new Ducati owners dropping a thousand bucks on a valve adjustment and not knowing what they're getting for it.
I believe these bikes should be kept running and mine will be fixed as I source parts at a reasonable price. I still have contacts and I have time. If it doesn't happen this year, it will happen next.
Thanks for all the info. You guys have been a lot of help.

[DewCatTea-Bob]

" although I have no idea when the pump ceased to work. "

____ It's at least clear to me that the pump was already busted before you got it.


" I don't know how long it would take to wear down a cam lobe over 2.5mm. "

____ In no less than 3 of the out of service oil-pump cases which I was involved with,
the damage was left uncared-for for long enough for the cam to become very excessively worn, like yours.
Unfortunately, the amount of mileage which took place without the pump working was never exactly known.
__ However, I did (one day in summer 1971) meet a fella -(a younger brother of an old school-mate) with a somewhat noisy 1965 250Scrambler... After riding with him a bit, I offered to have him come-over & see my DUKE which was just-like his except in better condition, where I then convinced him to let me check his valve-clearance for him, (after he had had a chance to hear MY '65 Scrambler run).
I first found that his ex.valve-clearance was near 60-thousandths too loose (and the oil-smell was not too good in there either!). _ At that point, I figured we should check to see if the top-end was getting any oil, and found that there was no sign of any oil reaching the top-end even after running between idle & around 3000 for over 2-minutes!
Of course he wasn't pleased with what I was telling him and even seemed to doubt my deduction that his oil-pump was likely not working. _ So I had only gotten the chance to reduce the ex.clearance down to about .020", and the intake-side never even got looked-at at that time !
Then we went for another ride, (this time ending-up at his place), and then found that his top-end had become extremely hot while the bottom-end was still fairly cool, (there should not be such a big difference in temp.!), thus proving my point (about no oil to the head), by having him feel his motor top & bottom, compared to that of mine _ Then convinced him we should dump & check his oil, which turned-out wasn't so bad (& bad smelling) as expected, but did have enough bits-of-crap in the bottom, that we only pored a little over half of it back into his motor, (as he then expected to buy new oil soon).
__ I came to know the guy as a regular riding-buddy, who continued to ride his DUKE just about every day it hadn't rained, all the rest of that year's season plus the beginning of the next. _ All with no further attention to the motor other than an oil-change (done not too long after we had dumped-out half his oil) !
__ Then one day early in the season of 1972, he found that he couldn't get his DUKE to keep running well for long enough periods to leave very far from home with it. _ So he finally offered to pay to have it's problem fixed. _ At that time I found that the only thing which was really keeping his DUKE from running well enough to keep going, was that the points-gap had run-down to next to nothing ! _ But I still allowed him to assume that the cyl.head needed to be pulled & checked along with the oil-pump cover.
__ Once the cyl.head was pulled-off, I manually worked it, turning-over the valve-gear,, I then could not believe the very small amounts that the valves were actually getting opened to ! _ Must have been between just 2 to 3mm for the exhaust & about 1mm even less than that for the intake.
After I removed the cam & rockers, I found that the intake-lobe's peak was worn-down to about 5mm and the exhaust-lobe was about 1/2mm less. - (Stock lobe-height is 7.8 & 7.5mm for that model.)
That was the most worn cam I've ever come-across ! _ It was sort-of impressive that his engine had still ran well enough for him, (although he had stopped using it for transportation to his work/job after he had learned how bad-off his motor must be,
there-after only using it for just off-road riding, but still often ridden as usual, even if not for as far).
__ We ended-up installing a new-set of piston-rings -(which I already had on hand for one of my own DUKEs), and just replacing the bad cam & rockers in his cyl.head, making further use of another used-set, which was already lightly scored-up (likely due to the standard-reason of gas diluted oil), but still deemed good enough for his neglected motor, (besides only costing him 10-bucks, [from the owner of an old 4-speed Monza basket-case, who also sold us it's oil-pump cover for 15-bucks]).
__ After all those major-parts -(p.rings, cam&rockers, & oil-pump) were replaced, he really didn't much care for the engine's new-found upper power-band, since he was then used to just plunking-around with it. _ But at least he went back to also using it for transportation to & from his work/job again. _ (A year later though, he ended-up trading his DUKE to a work-buddy for a 125-Honda.)
__ So back to the top of this,, it seems that a DUKE's cam & rockers can be ran without oil for at least one full (normal) riding-season, well before the cam & rockers get worn-down to the point when they can no longer do there job of keeping the engine runnable.


" It's also a problem for me to spend the kind of money being asked in order to replace the needed parts.
I believe these bikes should be kept running and mine will be fixed as I source parts at a reasonable price. If it doesn't happen this year, it will happen next. "

____ Instead of putting it off for so long, you might instead consider just getting another entire cyl.head thru eBay...
Before this year, ya could get one for under 200-bucks, but more lately I've noticed it's getting closer to 300 for one.
The idea is to buy & use one while you fix-up your own, and when done, just turn-around & resell your eBay head for a possible slight profit.
That seems to be what others are doing, with cyl.heads at least.
__ If you can't find one, I'd be willing to sell you a spare 350-head I have.


DUKE-Cheers,
DCT-Bob

[frankfast]

Eldert - I would like to purchase a set of oil pump gears from you. Can you PM me about the best way to do that?

Bob - Is the head from a 350 Scrambler - green/white cam?

[DewCatTea-Bob]

" Is the head from a 350 Scrambler - green/white cam? "

____ No, & no.
My spare 350-head is from a n-c Sebring but, that should not matter if you just want to run your 350 while your original head-project is on the back-burner, waiting for affordable parts to come your way for it.
__ Many buyers on eBay seem to think that the G&W-cam is the HOT cam to obtain (& indeed it is, for RACING!), so they're very sought after & thus get priced high !
What many of those buyers don't seem to realize is that when running with a muffler, a much milder cam will out accelerate their precious 'G&W' and pretty much stay even-steven at the high-end as well ! - (Unless both drop their mufflers at that point, at which, the G&W will then creep-walk away towards a higher top-speed).
__ If ya ever had a chance to alternately ride two 350s, one with a G&W and the other with a milder cam, I'm sure most would agree that the DUKE with the milder cam was the more fun to ride of the two.
__ I have a good deal of experience with this stuff, and thus have many stories to tell.
Ask around from any others who've also ever bothered to directly compare the results of various DUKE-cams' effect on performance, and see what they can tell ya.
__ So are you in want of a pleasure-ride(s), or are you going racing (withOUT muffler!)?


DUKE-Cheers,
-Bob

[Eldert]

Hi Frank

PM send

Eldert

[frankfast]

Bob - Thanks for the offer but since I enjoy tinkering with this bike more than actually riding it, I've decided to put the head back together piece by piece. This bike has always been a project and will remain so for the time being. I've got others for the pleasure of riding. You are right in that a milder cam would suit my purposes and they are easier and cheaper to get. However, since I have an open megaphone and a friend with a 250 Mark3 (I would never allow him to whup me, especially with an extra 100cc's), I'll wait for that green/white cam. I think finding a set of rockers in good condition may be more of a challenge and I can't imagine that anyone in the business of restoring them would charge less than a set of good used ones. So I'll plug along at a leisurely pace and keep prodding you guys for pertinent information. This forum is absolutely the best source for Singles data I've found. Keep up the good work.