Vento 350

[Muzz350]

Thanks Bob for the advice on cam timing. Yes the timing is 68BT - 95AB (for intake), & 84BB - 70AT (for exhaust). I think I will change the cam rather than alter the timing of the existing one. I have a more pressing problem at the moment as the bike stopped again yesterday. It is the 3rd or 4th time it has stopped without warning. I had my tools with me this time and there was no spark at the plug or power at the points however the lights , indicators etc all work ok. I have previously replaced the coil,lead, plug points & condensor. I trailered it home and have started poking around with my multimeter but I am not really sure where to look or what should or shouldn't have power when the ignition is on but the engine is not running. I hope this intermittent problem isn't the cause of my tuning problems as well. I have been treating them as separate issues. I have several wiring diagrams which don't match and are often 6V and they don't even tell me what size fuses to use(there are 4) . I should have replaced the wiring loom when I pulled it down. Is electronic ignition a good way to go? My old SS had little but faultless electrics and never left me sitting on the side of the road.
Muz

[Jon Pegler]

Muz,

Have you still got the original ignition switch fitted?
The switches fitted to the Ventos and Forzas were not very good.
They are not easy to repair as the back of the switch body is crimped onto the plastic internals.
When I first got my Vento on the road it kept cutting out at odd times.
I replaced the ignition switch and the problem was cured.
Hopefully I can include a copy of the Vento wiring diagram

Jon

[Ventodue]

The cast wheels add to the rigid feel of the chassis ... but do add a bit of weight

Now there's an understatement, Jon!

¡Feliz año nuevo!

Craig

[Ventodue]

There was no spark at the plug or power at the points; however the lights, indicators etc all work. I ... have started poking around with my multimeter, but I am not really sure where to look, or what should or shouldn't have power when the ignition is on. .. (the wiring diagrams) don't even tell me what size fuses to use (there are 4).

If you've got 4-fuse fuse box, Muzz, it would seem you've got a non-standard wiring loom - or maybe just a Japanese market version, seeing as you've got indicators 'n all . As you can see from Jon's posting, the standard Vento wiring is a master piece of simplicity ...

But no worries - from your description, it sounds like you've simply got no power to the coil. There should be a feed from one of the fuses into the low tension side of the coil. Check there first with a simple test light (ignition on, nat' ... ) . Prolly just a loose/broken wire.

Is electronic ignition a good way to go?

Well, you can Muzz; but it's not absolutely necessary IMO. I'm still runnning coil and points.

(What does an electronic ignition sytem offer you? Well, it gets rid of the points, so that's one less thing to maintain. And depending on what you get, it might give you the ability to change the advance, should you so wish. And you might get a better spark - which could be useful if you're burning a bit of oil.)

[Muzz350]

Muz,

Have you still got the original ignition switch fitted?
The switches fitted to the Ventos and Forzas were not very good.
They are not easy to repair as the back of the switch body is crimped onto the plastic internals.
When I first got my Vento on the road it kept cutting out at odd times.
I replaced the ignition switch and the problem was cured.
Hopefully I can include a copy of the Vento wiring diagram

Jon

Thanks Jon, I'll check the ignition switch. I opened up the other switches and found they had been repaired/rebuilt.
Muz

[DewCatTea-Bob]

By: 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. "

____ I have very little doubt that the camshaft you pic.posted is-not the cam-model originally-stock to the Vento you had removed it from, however it would still be nice to have it's v.timing double-checked anyhow.
__ When you get a chance, it would be very interesting to get the results of a lift-reading of your cam's lobes !
As they APPEAR, those lobe-lifts don't look to be any higher than that of a G&W.cam's. _ Usually, wilder cams have increased lobe-lift to go along with their increased v.lift-duration,, but your Vento-cam example doesn't appear to have much additional lift (to go with it's excessive additional duration).


" The paint dots on my spare Vento cam are discoloured with age and oil "

____ Yes, I do believe that that's the actual reason for why the "white" now appears as 'yellow' and the "orange" now appears as 'red'...
__ I've noted in the past that Scrambler-cam.models which have a 'white' color-code, had gotten their white-paint turned into a tannish-brown color,, and no-doubt it was more of a yellowish-colored contamination before much additional millage with blackened oil.



" the owner wanted a milder street cam fitting, "

____ So which cam.model did you replace his Vento-cam with ? _ And how did he like the change-over ? _ Was the overall-performance not notably well improved ? ...
__ I know that replacement of G&W.F1-cams with milder cams do indeed improve overall-performance, so with the Vento-cam being even wilder (than the G&W.cam), I'd thus expect an even greater improvement.



" my own Vento is very wooly in performance up to about 4500 or 5000 revs, due to the large valve overlap. "

____ The Rapido-cam's valve-overlap duration is 152-degrees, and the Lento's is only slightly less, at 146-degrees.
Whereas a street-worthy cam should have no more than 120-degrees of v.overlap.


" and probably out accelerates my 450, right up to 8000RPM. "

____ What cam.model does YOUR 450 employ ?


Fun-Cheers,
-Bob

[Jon Pegler]

Muz,

If you have four fuses and indicators fitted, you may have the wiring harness from a 250 Strada fitted.
I include a wiring diagram for that model.
See if that is like your machine.
The light switch is the same as the Sanglas S2V5, although you probably don't get too many of them in Oz.
They are available sometimes in Spain.
I also have a few used ones if you are in trouble.

Jon

[Ventodue]

If you have four fuses and indicators fitted, you may have the wiring harness from a 250 Strada fitted. I include a wiring diagram for that model.

And here's the Forza one, Muzz - 4 fuses, but only 3 used (apparently). Here, the feed for the coil comes direct off the switched feed to the fuse

[Muzz350]

Thanks for the wiring diagrams Jon. They look familiar but I'll have to brush up on my Spanish. I was there a couple of months ago (missed the GP) and I relied on my wife for interpreting so I guess I will do that again.
Muz

[DewCatTea-Bob]

By: Muzz350...
" Yes the timing is 68BT - 95AB (for intake), & 84BB - 70AT (for exhaust). "

____ It's rather odd that only one of the v.timing-points would be a little off spec, and yet the other three would be spot-on ! _ I'd normally expect that all four points would be a couple degrees or so, off-spec.


" I think I will change the cam rather than alter the timing of the existing one. "

____ That's of-course the most practical way to go, however it certainly would've been interesting to learn how the suggested altered set-timing would've worked-out ! _ I'm sure it wouldn't have made performance notably worse, but given all the wild durations of your cam, the suggested-change probably wouldn't have helped very much either.
__ What are you currently thinking of for a replacement of your stock Lento-cam ?
I'd suggest that you swap with a 450-Scrambler (which actually employ a w-c.250Scr.cam), because the 450 recipient could make fairly good-use of your Lento-version cam.model, (since larger capacity cylinders are relatively more difficult to fill-up, and-so thus your cam.model would-not seem as wild within the larger capacity 450-cylinder).



" I have previously replaced the coil,lead, plug points & condensor. "

____ What?, "points & condensor" !?
I thought all those Mototrans 350-models employed Spanish-made electronic-ignition systems !?


Duke-Cheers,
-Bob