Vento 350

[Eldert]

John is correct i did post a pic of different bottom bevel gears a while back



reposting it is faster then looking up the old thread

if the timing on the bottom bevelgear would be on the wrong dot the camshaft timing would be out by about 16 degrees
and this would be noticed in performance

Eldert

[DewCatTea-Bob]

" if the timing on the bottom bevelgear would be on the wrong dot the camshaft timing would be out by about 16 degrees "

____ Eldert is pretty-much right with his statement of "about 16 degrees", cuz each tooth on THAT gear is actually responsible for just-slightly over 17-degrees of crankshaft rotation.


" and this would be noticed in performance "

____ That's certainly true, as only 1-tooth off-place down-THERE would then alter the camshaft's intended factory valve-timing by too-GREAT of an amount for the engine to properly operate, (assuming of-course that the installed camshaft has it's key-way slotted in normal/intended-place).
__ However such purposeful misalignment can be partially countered by also purposely miss-aligning the UPPER bevel-gear (oppositely), on the camshaft... As each of that gear's 28-teeth are responsible for nearly 26-degrees of CRANKshaft rotation.
So therefore by playing-around with advancing one of those bevel-gears by 1-tooth and retarding the other by 1-tooth, ya can then ADJUST the valve-timing (of the installed camshaft) by a more reasonable amount of just 8.6-degrees (either advanced or retarded),, which can possibly be BENEFICIAL, without throwing-off the overall-v.timing by too awfully-much of an amount and provide a more desired power-output characteristic from the engine, (although such a smaller change would not be as noticeable as that which Eldert has warned of, [which of-course would be a GOOD-thing]).
__ I was waiting for Muzz to respond-back to my related post, to then bring-up this possibility,, since he had indicated that his Lento-cam's valve-timing may-possibly be 8-degrees advanced.
But since Eldert has posted HIS post here-above, I then thought that this is as good of a time & place as any, to bring-up this info.


Dukaddy-DUKEs,
-Bob

[Muzz350]

Thanks Jon
I make notes or take photos before taking things apart but I can't remember which dots I lined up so I'll check. I wish I had found this forum 18mths ago before I rebuilt the engine. It only had 5000km on it but sometimes it slipped out of 2nd gear.
Muz
NOTE : I just read the post "if the dots were out the timing would be out about 16deg". I have checked the timing and they are all perfect except the exhaust valve which seems to be closing abit early.

[Muzz350]

Hi
I ment had most been converted to left hand gear change like this vento. I read that for the Japanese market the later Ventos were changed.

Gear change conversion.jpg

No problem with the muffler getting in the way.
Muz

[DewCatTea-Bob]

" It only had 5000km on it but sometimes it slipped out of 2nd gear. "

____ In this case it's probably not due to the past employed shifting-method, as the 2nd-gear slip-out issue really is a common-problem with Mototrans-350s ! _ The dog-edges on the connecting gear are too easily rounded-off, (probably likely due to poor/Spanish metallurgy). _ (The same issue does also exist with the Italian-made 3rd.gear-dogs, but it's FAR-less common !)



" I have checked the timing and they are all perfect except the exhaust valve which seems to be closing abit early. "

____ Your rather sparse coverage on this matter leaves me to gather that you've found that your Vento's valve-timing is: 68BT - 95AB (for intake), & 84BB - 70AT (for exhaust).
__ Having the exhaust-valve somewhat-oddly close 8-degrees early is not a real big difference, (as it's only 3-degrees past the allowed 5-degree spec.variance), and-so not much of any concern,, and in fact, that particular off-spec reduction-variance actually helps to make your overly wild cam.model be somewhat milder, to better cope with exhaust-plumbing that's muffled & not straight-through.
If the other three figures could also be trimmed-down that 8-degree amount, each,, then you'd have a more desirable/milder (but still fairly wild) camshaft, which you'd probably find fairly-well suitable for your 350.
__ Referring-back again to the purposeful misalignment of the timing-marks on the upper & lower bevel-gears,, that possible option of altering your cam's overall-v.timing by 8.6-degrees is not a very useful change to make because your cam is so very wild that while resetting one or two valve-timing points towards the better, such bevel-gear timing alteration would unfortunately also reset one or two of the other v.timing-points towards the worse. _ However if you cared to give it a try, an ADVANCE-change (to 76/87 & 92/62) may possibly help your engine better cope with a muffler & lower-revs. _ However, that particular resulted overall cam-v.timing is not a combination-set which I-myself would ever actually opt to choose for purposely designing a cam to, for ANY application,, but that resulted overall-combo.change does stand a fair chance of providing a slight improvement for you.
Even if quite so, you'd of-course still be better advised to seek a camshaft from a w-c.250/450-Scrambler, (but not a LATER-model 350-Scr).


Hopeful-Cheers,
DCT-Bob

[Jon Pegler]

I believe that the Ventos supplied to Japan were left foot change.
The cross over shaft went through the swinging arm spindle as you show in your photos.
Many of the parts were standard Mototrans levers etc as used on the Spanish built parallel twin.
The later wide case gears were not generally inferior to the Italian made ones, but I think the shimming of the shafts was less than perfect.
This is just as likely to cause cog damage due to missed gears.
I think that some of the factory assembly quality control was lacking at Mototrans.
If a machine had been used in Spain, you could bet your life that it had never received any maintenance from day 1.

Jon

[DewCatTea-Bob]

" One thing that has not been mentioned is that most Ventos have two timing dots on the bottom bevel gears.
The Vento should be timed to the left hand of these dots, not the one that aligns with the keyway. "

____ Thanks much for that fairly important informative-info Jon ! _ But what-about the UPPER bevel-gear on the camshaft ? _ Does it also have a PAIR of timing-mark/dots (to possibly become confused with)?
If not, then it seems fairly strange that the Vento-camshaft would have it's key-way placed so very far-off from the normal TDC.center-point/line.



" Note the orange and white paint dots on the body of the cam, possibly a Mototrans peculiarity. "

____ Yes that's strangely peculiar,, as in the older-past, the color-code was usually dabbed on the threaded tip-end (of the shaft's right-side/end), (and would usually become washed-away by heated-oil),, but it's quite noteworthy that THESE color-code DOTs are STILL on-there to be found, (as seen on the shaft-core).
However I have to say, that that pair of color-dots no-longer appear as "orange and white" ! _ Rather, I see them as yellow & red (as pictured, [or red & yellow, as placed within a mounted engine] ). _ So it's questionable as to exactly why that color oddity is as it appears to be.



" On my own Vento I replaced the double coil springs in the head with standard hairpin springs.
I think the double coil springs are a bit too stiff. "

____ I agree that for a 350 (which can't rev as high as a 250), the outer coil-spring alone should be quite sufficient for use with a G&W.cam & milder cam-models, however I'm thinking that the inner coil-spring was deemed useful for dealing with the effects of the extra-wild Vento-cam (just during top-RPMs).


____ I've added adjusted versions of Jon's posted-pix, I have not "adjusted" any aspect of them other than to zoom-into the subject of his pictures ! - (Although I did shrink the pic of the shaft [showing the color-dots], as it was overly-large originally.)
__ I'd like to get an opinion concerning the actual COLOR of the color-code dots painted on the shaft-core, as seen in the picture posted below/here (or as originally posted by Jon).


Dukaddy-DUKEs,
DCT-Bob

[graeme]

Paint and hot oil?
Lucky it's still there at all. Yes it looks red and yellow

Is there a cam chart somewhere for singles like there is for the belt twins?

Graeme

[DewCatTea-Bob]

" Yes it looks red and yellow "

____ Well-then I wonder what's-up with that !? _ I was led to believe that the Vento-cam was supposed to be "orange and white" .
That it may actually be 'red & yellow' would be a good-thing, cuz the Orange&White designation-code has already been claimed to represent anOTHER Duke-camshaft model.
__ I'm glad to have it confirmed that my monitor's tint-bios isn't so way-off !


" Is there a cam chart somewhere for singles like there is for the belt twins ? "

____ Yes, there are at least a couple of them but, I ASSURE you that they are listed with a number of included errors !
Try looking at this link (to find others)... viewtopic.php?f=3&t=1182&p=8107&#p8058
__ If there's any Ducati OHC-single camshaft-model which you wish data on, I most-likely have it. _ So if you ask, I'll then bother to try giving it to you. _ (And if my supplied data doesn't match-up to that of another source, you need not wonder who's is actually the CORRECT-data, as that which I've gathered-up came only from Ducati-FACTORY authorized publication/sources.)


DUCATIly,
-Bob

[Jon Pegler]

I guess it cannot be proven which cam I have posted a photo of until I put it into a motor and degree it.
When I have measured the opening and closing movements of another Vento cam, they came up pretty close to the figures quoted by Mototrans in the riders handbook, with the Rapido settings.
Those measurements were within +or- 5 degrees for each opening and closing movement.
The paint dots on my spare Vento cam are discoloured with age and oil as Graeme suggests.
That particular cam came out of a low mileage Vento motor that was imported into the UK about 13 or 14 years ago.
It hadn't been used for a while as it had major gearbox damage, but the owner wanted a milder street cam fitting, so I acquired that cam as a spare for my own Vento.
Bob may well be right regarding the keyway on the Vento cam being in a slightly different position to an Italian cam, to allow for the different position of the lower bevels when lined up to the left hand of the two timing dots.
It's hard to tell without fitting the cam to a motor and checking opening and closing movements and neither my poor camera or my lack of camera skills would show up well in a photo.
In use, my own Vento is very wooly in performance up to about 4500 or 5000 revs, due to the large valve overlap.
After that it comes into its own and probably out accelerates my 450, right up to 8000RPM.
Handling is also excellent on the Vento.
The frame is stiffer than an Italian widecase frame,although very similar, but has taper roller head races as standard and a slightly shorter, stiffer swinging arm, pivoting on nylon bushes.
The cast wheels add to the rigid feel of the chassis, (Two types fitted- early Ventos used Italian FPS wheels in unpainted aluminium finish, later ones used a Spanish copy of the Speedline wheel, but cast in aluminium and painted gold) but do add a bit of weight , making the Vento a bit heavier than a late Italian Mark 3.


Jon