125-200cc Power valve balls

Hello everybody,

first I'd like to present myself: I'm French (I apologize for my poor english) and new owner of one of the last italian WR 125.

I've already readen a lot over this bike in the present forum, especially about carburator and power valve settings.

Concerning the power valve, I assume the quite expensive provini damper is probably the best way to improve the response of the valve, because it doesn't affect the revolution speed, at which the valves opens, but the velocity of the opening movement.
Unfortunaltely, the provini damper seems to be not available for the 125, but only for the 250-300.

In the french forum http://husqy.forumsactifs.com, I reeds about guys changing the size of the ball (from 8,7 mm to 7,9 mm (1/32 inch)).
Did someone of you already try this or something similar?

Regards,

Jean

...it is possible te edit the thread to correct the title?

jeanjean

If your newly registered no you cannot edit your first few posts. the moderator will step in.

Welcome jeanjean whats the issue with the current setup?
You want the power to kick in sooner? Yes heavyer ballbearings in the power valve actuator will do that.

hmmm, would this work on my 95?

If it uses ball bearings to actuate the power valve in theory yes but heavyer balls are required so tungsten instead of steel etc. think its tungsten similar to heavyer ones used in rekluse clutch.

An extra spring can be added to existing larger power valve spring - this is the Walt (wallybean) designed kit available from Halls - I believe .

A small silver spring was from memory what I used in the past which raised the point( revs ) of the opening of the power valve to increase torque - smoothness.

I would do this again for a 125 - I think it was a good mod .

Not sure on spring spec.s - it may be possible to just buy one spring locally

Hello everybody,

I submit the question only to satisfy my curiosity...
I've seen all the threads over the spring solution, was just surprised that nobody try the ball solution.

Although changing the balls size would probably affect both the rpm at which the valves open and the tpm when fully open.
This is the same with an additional spring acting from the beginning, that is to say adding some preload or at least from the same lengh as the original spring.

Showing the graphs published by MattR, I assume that the small silver spring is a bit shorter than the original spring and don't act from the beginning, but with some delay to extend the opening range of the valves.

Regards,

jeanjean