Camshaft Data

[DewCatTea-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. "

____ I also have found that working on DUKEs is a more fulfilling use of time than riding one, EXCEPT when riding with a buddy who's also riding along with ya on another DUKE !!
__ I didn't much care for the idea of selling my only spare Sebring-head right at this time anyhow.
I believe every DUKE should have a spare-head ready to go, if not an entire motor. _ But I guess if ya have a whole spare DUKE -(OHC-single), then that's even better yet.


" You are right in that a milder cam would suit my purposes
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. "

____ This is the same kind of reasoning I'd expect from the average Green&White-worshiper, as well.
I also was once such a proponent for the G&W-cams ! _ That is until I went to the trouble of actually testing the cams (plus carbs & mufflers as well) with two otherwise identically stock (motor-wise) 350-Scramblers (which were of-course originally exactly matched in power & speed), and running both together with just one varied part compared at a time.
That's when I got very disconcerting-results concerning the G&W vs. other cams ! _ In the late '70s after confirming the results that I had fist learned in 1972, I by then came to positively realize that the G&W-cam is not a cam that should be always preferred ! _ And in fact for a 350, it ought to be avoided for most any kind of riding other than trying for topping-out at a SaltFlats-Plain type of racing. _ Because ANY other std.production DUKE-cam seems to provide a better overall power-range in a 350 (with stock-plumbing). _ As the G&W-cam sacrifices gobs of low-end & (to a lesser extent) mid-range power, in exchange for just a slight-increase in added power only at the very top of the 350's RPM-range !
__ I was really awakened to discover that the various cams don't make as big of a difference as ya would expect for them to cause. _ I found that the only way to tell any real difference is to either make many,many runs down the 1/4-mile track-way, or run a pair of otherwise identically-motored DUKEs against each other along with equal weight riders. _ As rider weight of as little as 10-pounds can well over-shadow any engine-mod, (other than increased displacement) !
__ And also, open-megaphones (compared to mufflers), will also help DUKEs with MILD cams as well !
And any stock 350 will out-accelerate any stock 250, (as the 92cc displacement advantage packs-more-punch than any cam difference!), on up to at least 85-MPH! _ Only thing is, your friend's n-c 250-Mark3 (with it's extra high-gearing) will eventually reach a higher top-speed. _ So how often would that actually be a concern for you? _ Cuz once well past 85, the 250M3 can still end-up passing you, regardless of which-ever cam your 350 may use !
__ Ya may now be wondering how it could at all be possible for a 350 to out-accelerate a 250 and yet also be able to then have the 250 come-back & pass the 350, with a higher top-speed !? ...
Well that's actually due to both DUKE-engines having the same 'plumbing', so the smaller 250 can breath better and thus run up to a higher RPM !
A 350 would need the common / stock intake-port size of 29.5mm to be opened-up to 34.5mm, in order to then be able to breath-in equally as well as the stock 250M3 (or M1) !
(I once got a w-c 350 [with it's stock-cam] using a 32mm intake-port, to reach 105-MPH , [5-MPH less than what a 250M3 is supposed to be able to obtain] ! _ And that was without the gearing being reset/optimized for best top-speed !)
__ I've become amazed at how far-out the Green&White-myth has become as wide-spread as it has !
So more of us Dukers really need to get-out & do the ACTUAL comparison-work and also learn for themselves, and then discontinue being an added link in the chain of those who further spread the G&W-gossip ! _ As THAT cam does not deserve all it's praise just cuz it's capable of making the slight-bit of higher peak-power that it can (without muffler), in a 350 !


DUCATI-DUKES,
DCT-Bob

[frankfast]

I understand how strongly you feel about the benefits of the green/white cam and its lack of practical use. But if I was of practical mind I'd probably be spending my time on a Honda instead of a Ducati. And if Ducati made practical bikes they would have installed a cam that was better suited for everyday riding. I wish to leave the motor as it was created, faults and all, since it is a marriage of passion and not necessity. As a matter of fact, I do have another long term project in the wings. Stuffed in the corner is a frame from a CB450 awaiting the discovery of a motor collecting dust somewhere in a barn in the Midwest. Perhaps I'll be a little more practical building that cafe project. Probably not.

[miken5678]

I understand how strongly you feel about the benefits of the green/white cam and its lack of practical use. But if I was of practical mind I'd probably be spending my time on a Honda instead of a Ducati. And if Ducati made practical bikes they would have installed a cam that was better suited for everyday riding. I wish to leave the motor as it was created, faults and all, since it is a marriage of passion and not necessity. As a matter of fact, I do have another long term project in the wings. Stuffed in the corner is a frame from a CB450 awaiting the discovery of a motor collecting dust somewhere in a barn in the Midwest. Perhaps I'll be a little more practical building that cafe project. Probably not.

interesting bike.. i didnt know much about it until i caught this the other day

http://thekneeslider.com/archives/2010/ ... -for-sale/

looks to have some high maint schedules and although the bike design in that link doesnt totally fit my tastes I was suprised to learn that the shop was located where I used to reside in the middle of almost nowhere in fl... and with the right touch I am sure it would make a nice cafe style racer

[frankfast]

Hardly the early seventies based twin cafe project that I had in mind but an interesting exercise nonetheless.

[DewCatTea-Bob]

" I understand how strongly you feel about the benefits of the green/white cam and its lack of practical use. "

____ Ahh, maybe not so strongly as you might possibly think,, it's just that I think that there's way too many who've been lead to believe that the 'G&W-cam' is supreme-o, and/or that since it makes the best (std.production) cam for racing, that it's then got to be the 'cam of choice' for their DUKE. _ And so I feel the need to put a damper of logic on that line of reasoning !


" And if Ducati made practical bikes they would have installed a cam that was better suited for everyday riding. I wish to leave the motor as it was created, faults and all, since it is a marriage of passion and not necessity. "

____ I guess I understand for sure now that you're indeed actually not one of those who're caught-up in any of the G&W hoopla-hype, and seemingly merely wish to remain loyal to Ducati's creativeness as it was. _ If so, I think that's just fine, but, I wonder if by feeling that way, (regardless of whether or not completely logical), you may actually be in the state of being loyal more so to Berliner -(the U.S. importer), rather than to the Ducati-factory itself. _ As I've come-across bits of info which indicate that countries other than the U.S.A. received 350-Scramblers which more logically came stock with the same 'White' camshaft as Ducati's other w-c (250 & 450) Scramblers did. _ And until the 350-Scrambler came-out (for the U.S.),, in the previous-past, Ducati was always very quite good at well matching their various cams to their various DUKE-models !
__ If I myself were 100% loyal to Ducati, (I'm actually not!), I'd sure hate to have gone to the extra trouble & expense to exactly restore to that which I thought was Ducati's very-own works, and then afterwords learn that it was actually the second-guess-work of another involved entity's whim !
But then that's just me.
__ Also, it's going to be an extra trick to find the very same type of G&W-cam as the one you had, cuz so far as I know, BOTH the early 'w-c 350-cam' AND the '250F1-cam' were color-coded Green & White. _ And they both look so much alike, that ya can only tell them apart by the ex.lobe's lift, (which is about .35mm difference).
So I'd highly recommend instead, finding a Grey/M1-cam ! _ Cuz then not only will you know for sure exactly which cam you have, you'll then also have the best std.production DUKE-cam for obtaining the best overall-performance for your 350 (muffler or not!) !


" Stuffed in the corner is a frame from a CB450 awaiting the discovery of a motor collecting dust somewhere in a barn in the Midwest. "

____ The only two facts which allows me to justify wondering off-topic on that mere 'bike' model, is,,
1. - it's fairly certain that Honda copied Ducati's 200cc-motor's stroke of '57.8mm', (as Honda could've gone with an even 58.0mm stroke, and yet still stayed well under the 450cc class-limit!),, and,
2. - any of us who're familiar with the DESMO valve-gear set-up, should have a look-see at the very unique rocker-arm set-up of that particular Honda-engine, so as to note how Honda closes the valves of it's DOHC set-up, (which also has no coil valve-springs either, as well!) !
I found it quite well worth looking-over ! _ And perhaps Ducati should've copied that Honda-450's method for valve-adjustment, for their DESMO set-up !?
__ Has anyone else ever noted these facts concerning the CB450-K0, (starting in 1965) ?


DUKE-Cheers,
-Bob

[DucBevellvr]

This thread has become another especially interesting read for me!
For one thing, I'm reminded of one of the reasons why I got rid of my old 350 Scrambler. Many years ago when I still had my 350, I was at a bike show near a Harly shop when I met a guy with what looked to be a stock Sebring.
After checking out each others Dukes there, he lead me on a ride to show me his favorite set of backroads for riding. During our over 20 mile ride, we found our 350s to be pretty much evenly matched in every road speed situation, even though he was bigger/heavier and his 350 was geared higher and had a tiny 24mm carb on it!!!
Since my widecase 350 should have had it's stock green / white cam, I expected I should have whopped him in every situation when we raced, especially since he had higher gearing and was nearly 20 pounds heavier than me.
The guy swore his Sebring was totally stock except for his muffler's baffle had been removed, (and he also told me that wasn't easy to do).
My 350 also had it's muffler just like his Sebring's except shorter and with it's baffle still inside.

Before that day, I had thought my 350 was running as good as it should but since I couldn't ever pull ahead of that guy's Sebring, I figured that either his 350 really had some kind of racing cam in it, or my 350 had to have something wrong with it. And when I couldn't find any problem with it, I decided to sell it off (thinking it must be a lemon, even though I never raced it against any other 350 Duke).

I would really like to know if anyone else has ever tried running these two stock 350 models against each other, and if removing the stock muffler's baffle really helps performance very much? Also some of DCT-Bob's posts have me believing the green/white cam really doesn't work too good with a baffled muffler.

Thanks,
JeffP

[DewCatTea-Bob]

" Since my widecase 350 should have had it's stock green / white cam, I expected I should have whopped him in every situation when we raced, especially since he had higher gearing and was nearly 20 pounds heavier than me. "

____ That Sebring was no doubt one of the narrow-case 350-models, which have at least one advantage over any wide-case model ...
Their frame & motor are both lighter than your wide-case model's, which in this case of your's, ruffly canceled the difference of your body-weights, thus made the two man-&-machine-combos about the same.
Also, the Sebring employs somewhat smaller/lighter wheels (which are easier to spin-up & accelerate!), compared to that of most w-c 350s.
__ That a Sebring was still able to keep-up with your lower-geared & and larger-carbed w-c 350, is not at all a surprise to me since that match-out which you've told of, doesn't seem much different from that of my own experiences ! _ And I believe that the narrow-case models have another (lesser known) advantage over their wide-case counter-parts. ...
Although in the past Eldert has not agreed with my belief, I still contend that the shorter con.rods of the narrow-case engines provide more leverage and thus a bit more max-torque gets produced, as the pressure within the combustion-chamber is then, (compared to longer-rods), better directed towards forcing the rear-wheel to turn. _ (Although at the expense of cylinder-wall & piston-skirt wear.)


" The guy swore his Sebring was totally stock except for his muffler's baffle had been removed, (and he also told me that wasn't easy to do).

____ That's true, the baffle-unit within the stock Silentium-mufflers are indeed hard to get knocked out (of a used one, anyway).
And while the baffle does help, it doesn't really make a truely significant difference in cutting the ex.sound, (so I [and many others] used to pound-out the baffles in those mufflers, for a cooler [even though louder] sound).


" My 350 also had it's muffler just like his Sebring's except shorter and with it's baffle still inside. "

____ Then it's likely that your 350 was a 'Scrambler' model...
And that stock-muffler along with it's baffle, is certainly not a good-match for use with the Green&White cams !


" since I couldn't ever pull ahead of that guy's Sebring, I figured that either his 350 really had some kind of racing cam in it, "

____ That's a conclusion which many who don't actually realize exactly how real racing-cams actually are able to take advantage of the momentum of air at higher speeds, and so are too quick to assume that a 'racing-cam' must be the reason for an engine's power to accelerate regardless of whatever the RPM-range.
As true racing-cams are actually a trade-off, and thus trade good low-end power in exchange for relatively little extra high-end power, and really don't increase power across the entire power-range like many seem to think !


" I would really like to know if anyone else has ever tried running these two stock 350 models against each other, and if removing the stock muffler's baffle really helps performance very much? "

____ I have extensive experience with racing many different stock (as well as un-stock & non-stock) DUKE-models against each other, and the two models you're asking about are certainly included in all my experience !
But to keep it fair (for the sake of engine-power comparison), they should not only have very close to the same gearing but also the two riders very much need to be as close to the same size & weight as possible.
__ And yes, removing the baffle from those stock mufflers does indeed help a noticeable amount, however not as greatly for a Sebring (with stock-cam) as for the 350s with the G&W-cam !

____ Just let me know if you wish greater detail on anything covered here.


DUKE-Cheers,
-Bob

[frankfast]

Bob - Are all parts ( cams, rockers, etc.) interchangeable between 250 and 350 narrow case and wide case? I realize valve sizes are different. - Frank

[DewCatTea-Bob]

" Are all parts ( cams, rockers, etc.) interchangeable between 250 and 350 narrow case and wide case? "

____ They can be but, it's possible to run-into certain clearance-issues when mix-&-matching the various valve-gear parts of various models.
I know because I myself have done quite a bit of such parts matching (on occasions when I've had to combine batches of basket-cases to build whole DUKEs).
__ Besides the std.valve-heads being different sizes -(intakes of 36, 37, & 40mm & exhausts of 33, 34, & 36mm), the length of the valve-stems also vary depending on the intended type of rocker-arm to be used with...
As the few models which employ the rare screw-adjuster type rocker-arms, were originally meant to work with the valves which have the slightly longer -(by a couple mm) valve-stems.
__ A mechanic (with unoriginal parts) is more apt to run into clearance-issues when the valve-seats are worn, and especially after the seats have been ground ! ...
The worst possible clearance-issue is when the seats have been ground and you've combined the long-stemmed valves with standard (non-adjustable) rocker-arms, along with a narrow-case cam ! _ With this combo, it's quite possible to end-up with (unworkable) negative valve-clearance !
More likely though, ya can end-up with an irregular clearance (between the rocker-arm & valve-stem) that's less than the smallest-sized factory-made shim-cap -(2mm thick).
With one such situation, I had hopes to solve it's undersized clearance issue by trying-out several different pairs of std.type rocker-arms (which I had from a collection of such rockers, [as there's at least 4 differing styles of rocker castings]), in hopes of finding that one of the pairs may offer more clearance, but unfortunately found no more than a few thousandths difference between them !
I once had to grind-down both the valve-stem tip (almost 1mm) & the thinnest shim-cap (from 2.0 down to .8mm), in order to fill-up the substandard space and finally end-up with the desired valve-clearance.
__ If it weren't for such possible clearance-issues, then all the various valve-gear parts from all (non-DESMO) 175 thru 450 OHC DUKE cyl.head models, would indeed all be interchangeable !
At the other extreme,
(even with the valve-seats ground-down to their deepest factory-spec limit), the valve-gear combo of: the (more common) valves with the shorter stems; & the adjustable-rockers; & a wide-case camshaft -(which has smaller base-circles [compared to older n-c cams]),
there's no worry of any kind of clearance problem.
For any other/in-between situation of part-combos, you might try asking me, concerning any specific parts-matching still in question, in order to be more sure if the various related parts which ya happen to have, will interchange/match-up without any likely issues as I've now mentioned for such (various valve-gear) parts.


____ Another fix which helps to avoid the possible clearance-issue, is to get your rocker-arm's cam-follower face's radius reset to a somewhat larger radius, which will then take-off some of the material that uses-up some of the space in question.
__ I've since tried to recall more details about this subject (from the '70s), and I think the name of one of the places who did such work was called 'Performance Engineering', (or the like, who were located somewhere out near the west-coast).
I've also asked an old Duc L-twin friend who should've also known about it, but he could only currently recall of 'Delta Camshaft' (in Tacoma, Wash.) who were cheaper (and about as good), for refacing rocker-arms, (and at a much better price than buying new-rockers). _ He later called me back telling me their ph# - (1-800-562-5500), and to ask for 'Jerry', who's supposed to be the most helpful there. - (When I tried calling, there was no answer.)
Please let us know if ya get through and learn anything about this possibility.


Hopeful-Cheers,
-Bob

[frankfast]

So I gather from your explanation that using a set of rockers from a narrowcase Scrambler in my widecase Scrambler should not present a problem since neither incorprorate screw type adjusters. Also there shouldn't be an issue using the cam from the narrowcase. Am I correct?