bedell99

~SPONSOR~
May 3, 2000
788
0
I just removed my topend and started cleaning my powervalve. I have a problem. the powervalve is not opening up the sub exhaust ports and I really can't figure out why. When I trun the shaft it basically just opens up the main valve all the way. Any suggestions on why it is doing this. Also the screws that hold every thing together are on really tight and I don't want to strip them. Is it in you guys/girls experience that yamaha uses Loctite to hold on these screws. Any help will be greatly appreciated.

Erik
 
Feb 17, 2005
84
0
Arent the sub exhaust ports on the YZ250's opened by exhaust back pressure? Meaning the are not controled by the powervalve activator lever!

I havent had mine apart yet but my brother (who has always owned YZ's) was mumbling about something about exhaust backpressure and the sub ports in relation.
 

Blue 250

Member
Sep 5, 2005
42
0
Keep turning it and it'll open up the others. Right now your only turning it half way. No they dont use loctite, but there really cranked down.Becareful when tighten them down because I when I did on my old 04 I snaped the head off and it was a PITA to drill it out it tap it, so just snug them down. In my experiance my pv's never have carbon build up but just a bunch of spooge so I just spray it out really good with carb and choke cleaner and its fine. Becareful and good luck.
 

bedell99

~SPONSOR~
May 3, 2000
788
0
Thanks very much guys. You where right I wasn't turning it all the way. The sub exhuast are controlled by the springsin the power valve assembly and are metered. Very cool. I'm very surprised no one came out with any aftermarket PV devices to control the sub exhaust ports.

Erik
 
Top Bottom