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Yamaha Power Valve System guru?

J

JakesKTM

Guest
In search of the YPVS guru lurking around the Bay Area.... I need help with the power valve on my RZ350. Seems it is not functioning properly....:cry
 
i've messed with them a couple times. whats it doing?
 
Carbon build up i would think. Have you done a rebore at all and if you did, did you give the PV's a clean up? Some say let cylinders soak overnight in simple green and lube thoroughly after.
 
If the PVs are carbonized, you'll need oven cleaner and a bead blaster.

If you take the pipes off you should be able to reach in and move the valves by hand. (This might require disconnecting the cables first.) If they don't move, you'll have to disassemble. If they do, then I would think the problem lies with the actuating motor.
 
Hmmm, I know nothing about how these valves operate. But I am willing to learn. The symptom I described for another YPVS forum in the UK was unanimously cited as a PVS problem. Basically, the bike stops gaining power once it reaches around 7K rpm. I do not have a tachometer so I am guessing. Top speed is unattainable at the moment due to this loss of power. Also, the bike can stutter a bit in midrange.

I've been told to remove the exhaust while others say just remove the power valve cover and look at the cleaning cycle and if the valve rotates back and forth.

Removing the exhaust is not that difficult. You say I should be able to move the valve (up and down?) by hand? I'll try that first I think.

btw-I have no battery on the bike. It is maintained by a battery eliminator. Does that affect the power valve operation?
 
I was assuming the RZ350 YPVS was a guillotine valve. Oops, I guess they are rotary, but you should still be able to move them by hand. Remove the pipes and the covers.

Indeed it sounds like yours are staying closed. Unless your main jets are so rich the bike won't rev.

If you have a lot of miles on the bike and you've never had it apart, it's time to pull the cylinders, clean the PV spooge, and de-carbonize the valves.

BTW, Motul is really good for avoiding carbon buildup.
 
Thanks. I run Motul 800 with VP 103 race gas. I am not sure of the hours on the last rebuild, but I suppose it can't be too difficult? I've never had a 2 stroke apart. Plenty of 4 strokes (damn timing chains and plungers). Are there any super secret pitfalls when working on the top end?
 
The hardest thing about a 2T top end is its PV system. You'll laugh at how easy it is once you get it apart. Do a compression check first.

Sounds like you need to buy pistons, rings, gaskets, etc. and rebuild that thing. Maybe YPVS seals and bushings once you get in there and see what's going on.

Get a leak down tester too.
 
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