86 YZ125, here's one for the Pro's

[VTNewb]

Let me preface this with this list:

• Clean and oiled air filter
• New reeds
• New gaskets with top end (just new rings as recommended by engine shop)
• Jetted 1 main and pilot rich from stock as recommended by several google searches as a baseline

Now, the powervalve is verified working, however, the cover design is annoying in that it has two gaskets. One is paper and one is rubber. The rubber goes around some complicated geometry to make a good seat. The rubber is verified leaking, and as a result upon reving smoke shoots out of this part of the gasket on the cover.

Question 1:
Is there supposed to be a seal in the powervalve that prevents smoke from entering the powervalve cover chamber?

Question 2:
The bike runs a bit... mushy. Upon reving up (man does this bike have a large turn radius on that throttle), it hits its peak somewhere in the powerband, but if you just sit there pinned it'll rev higher and higher (at a slow rate). When it finally tops out at its REAL peak, the bike is snappy and performs like it should just for a little while, then it goes back to being mushy.

Is this caused by the powervalve leak or should I be suspcious about the compression?

 

[rmc_olderthandirt]

1) There is an O-ring that should seal the powervalve. The gasket & rubber piece shouldn't have to seal anything other than dust.

2) I would guess that it is running too rich. Try dropping the needle a clip position or two.

Rod

 

[VTNewb]

1) There is an O-ring that should seal the powervalve. The gasket & rubber piece shouldn't have to seal anything other than dust.

2) I would guess that it is running too rich. Try dropping the needle a clip position or two.

Rod

Thanks much. I'll pass this on to the owner and hopefully he'll order the seals!