YPVS System

[looey]

Does anyone know if any damage can be done (control unit, ecu, servo etc.) running the bike with the control unit unplugged from the servo ?.

It's actually on a TZR125 but some of the parts are the same as the 350 (29L etc.)

Reason is, mine isn't functioning as it should and at the moment the only way to get full power is to peg the valve in the fully open position or just do an ignition cycle then unplug the servo from the control unit then it stays in the fully open position.

Cheers

[justyr]

looey,
there is one key signal between the cdi unit and the pv controller (black and yellow wire on lcII). Make sure this connection exists ok.
Also make sure that the pv control unit is getting it's power (12V, brown wire). This brown wire should also be fused, check fuse is ok.

The pv control unit takes in a signal that represents engine speed (black/yellow wire) and computes from that what the pv motor position should be.

J

[looey]

Hi J,

Yeah I have a post running in the advice section for the problems with my YPVS system. It's all wired up properly and everything does what it should but the valve doesn't get to the fully open position until (10,000rpm ish) which is after the bike has run out of puff when riding it.

It's almost as if it thinks the bike is revving lower than it is, so the the valve opens later than it should ?

[midlifecrisisrd]

Hi,

Commented in your other thread.

It does no harm it being disconnected as it will either just have no power so will not operate or no signal which means it will cycle when switched on but never do anything.

Just remember the fact that although it is faster and revs higher with the valve opened manually this does not mean it is the way yamaha intended.

As said the F2YPVS does not fully open till 10200 when peak power is 8500 so if you manually opened the valve it would theoretically make more power and rev higher.

Another thing to consider is does the jetting need upped, it may be that it is weak and will not pull to the revs the bike needs to open the valve but will rev when fixed open. Also is there a restricter in the exhaust to further limit the UK bike.

At least yours runs, mine is the opposite, valve operates as should but the feckin thing won't run well enough to pull it.

Steve

[looey]

Yeah mine does run and it's rideable, but it's just like riding a strangled restricted 125 with the valve operating.... lol

The jetting should be fine as Yamaha quote the same for the restricted and unrestriced bikes ?.

[davey]

Looey,
Standard jet on resriction is a 170. Derestricted is 210.
I have a tzr r and is a bas--rd to set up carb especially.
What carb do you have on it?

[looey]

This is a 1989 2RK model and has the std VM26SS with a 180 main.

It flies at the top of the rev-range with the valve pegged open but has no bottom end at all obviously. But with the valve working it has a good spread of power up to say 7,000 - 8,000 rpm but never gets that same top end power as with the valve pegged open ?.

[davey]

to check the pwr valve you need to remove the exaust and see where the valve sits after finishing its 3 cycles .
it should stop at the fully open position as this is where it needs to be when the engine starts.
mine is a 4fl french model unresricted so im nor sure wether yours is restricted or not.
Having said that the 4fl did come with some resrtiction one of them being the pipe and the other being the jetting .
from reading your posts i would guess that it restricted at the pwr valve mate and there are some ways to alter this .
If you check out the 125 yam forums they will shed some light on which wires to change mod etc etc.

hth

[midlifecrisisrd]

Hi,

Did you see my comment in your other post regarding whether it should have a combined ( 3wire ) or separate controller and servo (5wire)

Just a though if it is not working correctly

Steve