Vespatronic cutout at 3800Rpm

[Thebat18]

Hi

I have a problem with my vespatronic.

I have tried to adjust the carburator to come around the problem, but nothing helps.

So it seems like it is the vespatronic.

It cuts out at precisely 3800 and at 4100 it is all fine at it rews fine. thro the range. (Got a KOSO rev-counter)

But this makes a huge problem starting from a standstill.

Tickover is fine and it revs freely in neutrual gear - unless i revs slooowly up, then it cuts out again.

Anyone experienced this?

My setup is:

Malossi 136, ported up and with a direct reedvalve

Mikuni 24mm.

Stoffi INOX exhaust ( similar to PM40)

Racecrank

Vespatronic.

[SpecialHeizer]

moinsen,

so wie ich kollege thebat18 verstanden habe, hat er ein ähnliches problem wie ich mit der vespatronic.

32er mikuni hatte ich eigentlich mit hp4 ganz gut eingestellt. sicher noch verbesserungsfähig, aber die karre drehte in allen bereichen sauber hoch. seitdem ich auf vespatronic umgebaut habe, habe ich bei ca. 1/3 - 1/2 gas ein ziemlich heftiges stottern, das ich einfach nicht weg bekomme.

untenrum läuft die kiste ok, obenrum auch. wenn ich den hahn direkt ganz aufreisse gehts auch, nur langsames beschleunigen funzt nicht. sollte ja eigtentlich ein klassisches vergasereinstellungsproblem sein, aber ein mehrmaliges wechseln der nebendüsen und clipstellungen hat genau gar nichts bewirkt. war jetzt letztens mit einer 22er nd und clip auf magerster stellung unterwegs, da wurde der zylinder schon arg heiß - das problem besteht aber weiterhin.

hat da jemand ähnliche erfahrungen gemacht? was könnte es sein?

@thebat18: did you find out what the problem was? i have the same difficulties..

Bearbeitet 31. August 2008 von SpecialHeizer

[Mr.Jugend]

Ich hatte ein ähnliches Problem mit der Vtronic, allerdings wurde bei meinem das Stottern mit jedem Gang besser, d.h. im ersten wars richtig krass im zweiten deutlich spürbar, im dritten und vierten dagegen praktisch weg. Besser wurde es nur nach längeren Vollgasfahrten. Nadeln, Clipstellungen, Nd und Hd - Änderungen haben nichts signifikant bewirkt.

[reelay]

Ich hatte ein ähnliches Problem mit der Vtronic, allerdings wurde bei meinem das Stottern mit jedem Gang besser, d.h. im ersten wars richtig krass im zweiten deutlich spürbar, im dritten und vierten dagegen praktisch weg. Besser wurde es nur nach längeren Vollgasfahrten. Nadeln, Clipstellungen, Nd und Hd - Änderungen haben nichts signifikant bewirkt.

Würde bei dir spontan auf zu mager tippen.

[SpecialHeizer]

thebat18 hat noch immer mit dem problem zu kämpfen und glaubt mittlerweile, dass es wirklich die vespatronic selber ist.

ich hab am samsatg nochmal alles gecheckt - vom zzp über bedüsung, diverse kerzen, den cutout hab ich auch mal etwas erweitert - keine besserung. vergaser würde ich ausschließen, lief schließlich mit hp4 schon recht ordentlich.

[Thebat18]

HUGE BRAKTHRO!!

the problem lies in the powercurve, as witch the vespatronic is programmed with.

Please read what "KTy" is writing here http://www.germanscooterforum.de/GSF_Proje...31#entry1042831

Update from this morning... :)

When the engine was "cold", it was running great with the above timing curve. Then, after 5-10minutes of normal street driving, little by little, it became more and more difficult to drive at "low rpm", but still doing fine while idling and also at mid and high-rpm...

In the end, I bypassed it as it was undrivable for street use. The timing curve I was using yesterday was better for low rpm...

So I guess it was too much advance too soon (low rpm)...

I will continue to experience ;)

And if you're wondering, I have a Chamion L82C spark as it is pretty cold out there and also because I'm focusing on low and mid-rpm...

I found why I had some trouble at low RPM... It is now fixed ! It seems even smoother than without ! :love:

This is the test curve for tomorrow !

27° at maximum torque (4000rpm)

16° at maximum power (6000rpm) !

To cut the story short.

The symptoms he discripe fit PERFECTly with our problems. So now we know that the programming of the courve is problem.

but now - How to change it?

Is it a faulty unit?

[100 spezial]

what happens when you retard a bit the ignition? also for example, you are starting now with 20°, start with 18°..

[Thebat18]

I will try adjusting the ignition on the vespatronic, by moving the statorplate, but i think the entire ignition-courve in the vespatronic is wrong - at least for my scoot.

I wonder if the graf is diffrent for a PX/smallframe. ( i might have a px vespatronic on my primmy)

'The graf on the picture is showing KTy's work :)

[matzmann]

Try to reduce the gap of the spark plug or use silver/iridium ones. That cured my vespatronic problems.

Gruß aus Kiel

matze

[Thebat18]

Cool.

I will try getting one.

The gab on my current sparkplug is 0,5mm. Should i set it a bit smaller, like 0,3mm?

[SpecialHeizer]

i am also going to try this, but the last time it was really undrivable - there´s only little hope. i am also going to try a friend´s vespatronic within the next days and let you know..

[undis racing team]

@thebat:

problem solved?

[Thebat18]

Nothing new yet :/

Tryed smaller gab and an Iridium-sparkplug, but it did not change anything.

I am about to find Tino Sacchi's email adress to ask about the powercurve, and wether or not there are diffrent curves for the diffrent models of vespa. but i cannot find it.

I have a little hope, that SpecialHeizer, will cast some light on the problem, as he was going to try another Vespatronic-unit. :)

As they say, i am currently on hold and Stay Tuned :)

[amazombi]

advance/retard the statorplate. if problem is not changed it is not the ignition curve. i personally do not believe it is the curve anyway. i think you (and kty) have a carburation problem, he managed to overcome his problem not by solving it, but by worming his way around it. if it was an advance/retard problem, why does it only appear when the engine is hot?

please also keep in mind that even if two problems seem to show the same symptoms they do not necessarily have to be the same problem. i am using two vespatronics on very different engines, and they work great on both. they did not work great while the carbs of the two engines were out, i wouldn't call that an ignition problem though.

[Thebat18]

Amazombie;

You are partially right.

My question is allso, why it only ouccurs when the engine is hoy. that sound like a bad ignition-coil on an old statorplate.

but on something like these new components witch have been stress-tested, it could not have something to to with that.

but then again, i have tryed a lot - but not advancing the timing ( moving it away from TDC).

I will try that.

Could it have something to do with raising the cylinder 1mm?

I followed this manual when porting the cylinder http://freenet-homepage.de/landrover/seite1.htm

[SpecialHeizer]

like i said - with the hp4 my scooter ran ok, so i´d say that the carburator was also tuned ok. when i first tested the vespatronic it also ran ok. i tried adjusting the carburator a couple of days later but the more i drove the worse it got. in the end it was undrivable (i even tuned the carburator to the first setup when it ran ok). no matter waht i tried there was no change but getting worse. hopefully next week i will try a friend´s vespatronic.

[100 spezial]

any news?