opposed twin 18.5hp

[nissinator]

ok so i was riding around outside and out of no where i lost all power turns out my #2 piston wasnt firing so i pulled off the head and turns out the exhaust valve is stuck but i can hit it back into place and turn the crank and it will open just fine but it wont close???? spring looks fine and i was thinking maybe the cam shaft is broke but it still pushed the valve open soooo any ideas? much help appreciated

 

[Russ2251]

Could be bent or just coked up.
If bent, replacement will be necessary. Guide will most likely be messed up as well.
If coked up, a simple remove and clean (stem and guide) is all that is needed.
Check springs.

 

[nissinator]

its not bent so ill try and remove it and clean it but its a pain to do without a spring compressor lol

 

[nissinator]

well it moves very smooth but its the little rod that pushes open the valve but it doesnt close any reason the rod is getting jammed...i really dont want to tear into this engine

 

[OzFab]

You mean the push rod: it may be bent or skewed. Looks like you're gonna have to pull the engine down somewhat; the only way to get them out is remove the cam

 

[r97]

To really determine if parts are bent you really should remove and inspect/measure them.

 

[Doc Sprocket]

I just checked my service manual. That tappet (lifter) is part # 691800 just in case you need to order one...

 

[OzFab]

To really determine if parts are bent you really should remove and inspect/measure them.

You can't see a 0.005" bend with the naked eye, which is all it takes

 

[machinist@large]

You can't see a 0.005" bend with the naked eye, which is all it takes

That depends on your level of experience; but yes, if you don't work with those types of tolerances every day, you most likely won't be able to see it without a dial indicator.

 

[nissinator]

ah ok well guess ill have to tear into it tomorow will be more an likely replacing it