Concerning Yamaha Power Valve failures

[Lokair]

Thanks for the info, I have two more ?s. I disconnected the exhuast valve from the push rod, and moved the Exhaust valve to the extreams while slowly pushing the kick starter down, it missed the piston, everytime. Do I need to replace the valve? Next the I mesured the stop and it fall int owhat eric gorr says is acceptable so this also leads me to beleive that I do not need to replace the valve or the stop. True or not?

On a side note. I am not sure the valve was functional when I got the bike(being that the pushrod bolt was less than finger tight), would having it disconected harm the bike in any way? Also could I not put a stop on the rightside of the motor(by adding a tang under the screw that would have a limiter that would stop the exhaust valve lever, outta brass), or has this been tried ? If I try this I will post a photo and directions.

 

[Rcannon]

Look inside the exhaust port. If your powervalve is hitting it will obviously do serious damage. The lucky part is this. If you catch it early enough it will polish a line on the piston. Eventually it will destroy everything, but you do have some time to catch it. The line is impossible to miss.

The stop sounds like a good idea. Still it is easy enough to file a little more clearance on the edge of the p/v.

 

[Lokair]

Ok I just looked at the piston, no line, so thats a good thing. I will still file the valve for a little extra. Thanks for all the advice and help, this thing confused the heck outta me. I am learning all the details of a 2 stroke with this bike. If I have a few more ?'s I will post them here.
Lok

 

[Rcannon]

Sounds good. I will try to help if I possibly can.

 

[smooth528]

huh!!! what cover are u talking about making?