450 Mark 3 engine rebuild and cam change

[DewCatTea-Bob]

[quote= machten ...
" Thanks for moving this from the other thread DCT-Bob. "

____ I didn't actually move anything, but rather Quote-copied it over to this more suitable thread.



" I apologise for my hijack. Graeme threw me the bait and I took it "

____ But there's really no need at all for any apologizing Kev, as neither you nor Graeme actually 'hijacked' that other thread ! _ As what had happened over-there is a rather regular occurrence of jumping onto a related tangent, which often can't be helped.
(A true-hijacking of a thread would be when a consecutive series of posts have started covering a totally-different unrelated & intangible subject which has no correlation to the containing thread's original topic-matter.)
__ If you didn't have this preexisting thread already established on the very-same subject-matter that the other thread had jumped-to,, then as a normal matter of course, we probably would've simply remained staying over-there.
It's just that I realized that after I'd get-done with all my response-posts to everything I wanted to further comment on,, that by then the thread would then be pretty-much the same as having become utterly hijacked, especially after all the inevitable follow-up posting would likely well overwhelm the original thread-topic postings ! _ And I also felt strongly that the further resulting post-discussions on the particular developed-subjects of specific-interest really ought-to rather be located within your established thread which had left-off on pretty-much the very-same identical subject-matter, (and I've long expected that when the specific subject-matter once-again finally came-up once more, that it really ought-to take-up within your established thread on the topic).
So it was a very-good fit to bring all that developed-matter over to here !



" there was a fair bit to respond to, so please forgive the length of this post "

____ It's for that same reason that I logically chose to submit my various post-responses within the five or six (corresponding)- individual response-posts, instead of putting all my accumulated response-comments within just one huge post (which I'd probably then never get-around to getting properly edited !).



" I have
had the opportunity to compare
my 450 Mark 3 equipped with the G&W replica cam
and a 450 Desmo. My impression was that the springer performance was about equivalent to the Desmo. If anything, I thought my Mark 3 may have the edge, "

____ I doubt that a mere 'seat-of-the-paints' comparison could ever notice the difference,, but while the valve-timing of the two cam.models is essentially the same, the cam-lobes of the G&W.cam do have a slight valve-lift height advantage (over that of the std.DESMO-cam), which of-course increases the 'average-lift'.
However the DESMO-cam.lobes rather have the advantage of slightly steeper lift-ramps (which increases lift-rate), and that factor also increases the average-lift. _ And-so that should make-up for the disadvantage of their shorter lobe-peaks.
__ So the bottom-line is that the two cam.models ought-not exhibit any noticeable performance difference.



" this experience provided to me nothing to contradict Bob's statement
and some evidence to support it. "

____ And of-course the revelation of your experience should be no surprise to anyone, as the Blue&White/250DESMO-cam -(standard in all std.production DESMO-models), was based upon the Green&White/250F1 racing-cam !



" Perhaps I should have said " I think I've lost next to nothing down low for normal street riding ". "

____ Fairly true enough, as riders don't normally make much use of low-RPM acceleration-power for long enough to notice it, (as they rather shift to keep engine-revs revving higher).



" I was expecting to have a noticeably reduced low RPM tractability in normal riding (like I found with Lex's 350 springer with the G&W cam). I haven't found this to be the case. "

____ Instead of expecting similar performance-characteristics results as like that of a 350, (displacement-difference aside, of-course),, you rather should've anticipated the same as that of the 450-DESMO.
__ So what had you been thinking before,, that the G&W.cam was even wilder than a std.DESMO-cam, or what ?



" I think it is ever so slightly detectable, but the pull from 3000RPM seems to me to be quite similar. "

____ If you were to ever try the side-by-side low-speed acceleration comparison-test that I previously covered, you'd then see how very un-similar the low-end power-output really actually is (between the White and Green&White cam.models) !



" No. I'm referring to the long one standard on the later Mark 3s (see picture below). "

____ I've unfortunately never had one of those newer Silentium-models to have ever examined.
Do you know for-sure whether it's any more heavily baffled than the pre-1971 version ?



" It worked OK with the White camshaft
With the G&W camshaft installed with the "new" Silentium, just over 4000RPM the bike will start missing (as in not firing). "

____ That seems highly odd ! _ So I still think something-else has to be contributing to that strange result.
Is that not the same Silentium-model employed on the later 450M3D.models ?
In any case, it would be of keen interest to see what result would be found with that very-same muffler installed on the 450-DESMO !
And if & when it's found that the results of that test is-not the same and rather as normally expected, then you'd know for-sure to suspect that there's indeed another factor that's contributing to the over 4-grand strangeness.



" although I'm not concluding anything, merely saying I wouldn't be surprised if that was the case. In fact, as I posted in response to Graeme, I intend to test that out for myself sometime. "

__ Well whether a change to a wilder-camshaft or a change to an open-exhaust makes the greatest power-improvement, is very relatively dependent ! ... Cuz if ya combine a wild-cam with a very restrictive muffler, the overall power could actually DECREASE across the entire rev-range, (sorta-like what pretty-much happened with Berliner's 350SSS). _ Whereas if the ex.system-muffler is already fairly un-restrictive to begin with, then the installation of a wild-cam will make a much-greater power-boost contribution rather than that which a substituted fully open ex.system would provide !
__ I've done so many comparison-tests that I don't well recall them all, but I believe I've included a comparison-test fairly similar to what you're referring-to.
I gather you'd like to know which combo would yield the greatest power-boost,, a 450 with stock muffler & G&W.cam, or a 450 with stock White-cam & free-flowing open-exhaust...
Well while the later seemed to have a slight acceleration advantage in 1st.gear from 15-MPH, the two combos otherwise seemed to be pretty-much a tie overall upwards towards 80MPH. _ (In that comparison-case, the other rider was taller & skinnier than me but within 10lbs weight difference,, and swapping-over 450s didn't make any really noticeable difference).



" I also wanted to indicate that before he goes to the effort and expense of a cam change, try changing the exhaust to a more free flowing system first. "

____ I certainly agree that Graeme should try comparing his 450-Scrambler with a free-flowing ex.system against another similar accelerating bike & rider, before changing it's camshaft !
__ However he has no good reason to install a G&W.cam since it will just make his 450Scr's cyl.head perform pretty-much the same as his 450R/T-DESMO.
So he should rather install his M1-cam.model, as that cam.model makes a 450 the most fun to ride (pretty-much regardless of muffler-type) !
____ And you-yourself Kev, really ought-to try-out your G&W.cam-equipped 450 with a 'straight-pipe' extension in place of any muffler ! _ Cuz then you'll get a chance to experience the WOW-factor that the G&W.cam provides for the 450, (before you reinstall the stock/White-cam) !
If you can't acquire a shorty-megaphone, then try substituting a vacuum-cleaner extension-tube or std.sink drain-pipe (that's 8 to 14 inches long) over-onto the tip-end of the ex.header (in place of the muffler), so as to just get a temporary test/trial-run to discover exactly what you've been missing from your 450. _ (And if you're like me, you then won't ever want to go-back to any muffler ! _ And you'll no-doubt wish you had done-so back when you were riding that mountain-run.)



____ (In case it hasn't yet been noticed,
I've finally-edited the previously unfinished post on the previous-page [with a Ducati-pic now added]).


Duke-Cheers,
-Bob

[machten]

To continue...

" I was expecting to have a noticeably reduced low RPM tractability in normal riding (like I found with Lex's 350 springer with the G&W cam). I haven't found this to be the case. "

____ Instead of expecting similar performance-characteristics results as like that of a 350, (displacement-difference aside, of-course),, you rather should've anticipated the same as that of the 450-DESMO.
__ So what had you been thinking before,, that the G&W.cam was even wilder than a std.DESMO-cam, or what ?

I confess to being relatively uninformed on the various non-Desmo camshaft specifications employed by Ducati in the wide cases until about 2012. Whilst I was aware of their existence, my interest in them was not sufficient to spur further action. I was also more interested in playing around with my 250 Mark 3 D at the time. In 2012, I first rode my friend’s 350 Mark 3 and noticed the remarkably different performance characteristics compared to my 450 Mark 3. That changed things and immediately prompted the thought “Why is this so?” and after some research “I wonder how that camshaft would go in my 450?”. It wasn’t until much later I read one of your posts regarding the similarity of the G&W to the B&W Desmo camshaft. I guess I still had some (probably irrational) doubts as the “little down low” effect on the 350 was so noticeable. It would seem (assuming my camshaft is a faithful recreation of the G&W in Lex’s 350 – and until I can dial them both I can’t be certain) that an additional 100cc’s makes a lot of difference.

" No. I'm referring to the long one standard on the later Mark 3s (see picture below). "

____ I've unfortunately never had one of those newer Silentium-models to have ever examined.
Do you know for-sure whether it's any more heavily baffled than the pre-1971 version ?

and

" It worked OK with the White camshaft
With the G&W camshaft installed with the "new" Silentium, just over 4000RPM the bike will start missing (as in not firing). "

____ That seems highly odd ! _ So I still think something-else has to be contributing to that strange result.
Is that not the same Silentium-model employed on the later 450M3D.models ?
In any case, it would be of keen interest to see what result would be found with that very-same muffler installed on the 450-DESMO !
And if & when it's found that the results of that test is-not the same and rather as normally expected, then you'd know for-sure to suspect that there's indeed another factor that's contributing to the over 4-grand strangeness.

I’m going to address this in a new thread on “Late model wide case exhausts”.

____ I've done so many comparison-tests that I don't well recall then all, but I'm sure I included the comparison you're referring-to.
I gather you'd like to know which combo would yield the greatest power-boost,, a 450 with stock muffler & G&W.cam, or a 450 with stock White-cam & free-flowing open-exhaust...
Well while the later seemed to have a slight acceleration advantage in 1st.gear from 15-MPH, the two combos otherwise seemed to be pretty-much a tie overall upwards towards 80MPH. _ (In that comparison-case, the other rider was taller & skinnier than me but within 10lbs weight difference,, and swapping-over 450s didn't make any really noticeable difference).

Yes. That’s exactly what I’m wondering. The Conti style pipe I have yields good performance, the only downside being that it is quite loud and can result in me feeling a bit guilty if I head off on a ride at 6am on a Sunday morning. I get over the guilt pretty quickly, though, so it’s just something for my own enlightenment really.

Thanks for your insights.

Kev

[DewCatTea-Bob]

____ Good-day Kev. _ It's peculiar that you've somehow quoted older post-wording of mine that had been edited-away 7-hours before your post became posted.
And-so I wonder if you ever noticed my edited post with additional text (which became available about the same minute in time as when I also replaced the previous single-picture [showing your ex.system], with the present combo-pic [that includes a close-up of just it's muffler]).




[quote= machten ...
" I first rode my friend’s 350 Mark 3 and noticed the remarkably different performance characteristics
I read one of your posts regarding the similarity of the G&W to the B&W Desmo camshaft.
I still had some
doubts as the “little down low” effect on the 350 was so noticeable. "

____ (Not really meaning to exactly take-up with the very-same line of thought as you were discussing, I've just quoted parts of your post-wording to lead-in to the following details that your quoted-wording has inspired.)
__ Your notations that Lex's 350 suffers such notably lacking low-end power-response, has begun to lead me to suspect that his 350 may have some other contributing factor (besides a likely 250F1-cam) that could be causing it to have even worse low-end response than expected as stock.
I've come to consider this possibility at-least partially due-to the following...
__ Just as a 350's low-end power gets hampered by the wild G&W/B&W.valve-timing, your 250-Mark3D should likewise suffer even more-so !
So when you must've become aware of the even further lack of low-end power-response of the 250 (compared to the 350),
it then seems you would've figured to expect pretty-much the same kind of low-end response improvement that the 350 has over the 250 for also the 450 to enjoy over the 350.
In other-words, the 450's improved acceptance of the wild valve-timing shouldn't have come as any surprise to you, (as the 450 to 350 difference would be a natural progressional-step of the 350 to 250 difference).
So since this seems to have been missed by you, I'm thusly led to consider that the 350 may-not be as strong above the 250 as it ought-to be.



" It would seem (assuming my camshaft is a faithful recreation of the G&W in Lex’s 350
that an additional 100cc’s makes a lot of difference. "

____ This aspect of the concern of the effect of displacement difference on the wildness-factor of cam.valve-timing, really ought-to have rather been covered prior to the related details in the paragraph above.
__ Just as wild-cams depend on high-RPM to create higher intake-tract velocity & air-momentum for fuller filling of the cylinder of smaller displacements (when the valves are then only open very briefly), the extra 100cc of volume-demand naturally also creates the same degree of vacuum based effects at lower RPMs. _ So-thus the wild-cam isn't quite so 'wild' for larger cylinder-volumes. _ (And why the 250 & 350 engines [with the same wild-cam] more-so suffer low-end wise, as the reduced volume-demand of their smaller cyl.displacements are rather more easily satisfied at low-RPM, [thus-then able to expel some of the compressing charge (which had just been pulled-in), before the valves get their chance to close (thusly leaving a reduced charge-percentage resulting with a correspondingly weaker ign.pulse), whereas a 450 (with it's greater volume-demand) is still demanding more charge-volume at the same point, along-with continued forward charge-velocity (thus fuller cylinder filling during low-revs)].)
So this is the reason for why the 100cc difference is able to create such a noticeably stronger 'low-end response' difference (above & beyond that which the 100cc itself accounts for), with the same wild-cam at low-RPM.


Dukaddy-DUKEs,
-Bob

[machten]

Hi Bob,

It's peculiar that you've somehow quoted older post-wording of mine that had been edited-away 7-hours before your post became posted.
And-so I wonder if you ever noticed my edited post with additional text (which became available about the same minute in time as when I also replaced the previous single-picture [showing your ex.system], with the present combo-pic [that includes a close-up of just it's muffler]).

I'd started a response off line earlier in my day (we're 13 hours out of synch) having copied your post at some earlier stage. I usually try to leave it a day or two but I knew I was going to be pushed for time then with work stuff, so I got an early(ish) start using your initial post as a framework as I had to go and research some of the (related) silencer stuff.

Regards,

Kev