few q's about power valves.
--how do you get to them
--how do you clean them
--how difficult is it to get to them and clean them?
--what can i do to prevent them from gunking
--what can i do to prevent them from failing?

you already have powervalves on your gpr. you should get the performance valves from riva. these have increased reliability. i believe motul makes a powervavlve cleaner you add to your gas which cleans the valves

Checking / Cleaning / Replacing Power Valves

Reference the Riva Original Parts Finder for explosion diagram (Cylinder Crankcase 2)

http://216.37.204.203/yamaha_OEM/YamahaPWC.asp?Type=13&A=80&B=4

Remove the head pipe and OEM stinger pipe. You do not have to remove the manifold.

Remove the cylinder head.

Remove plastic linkage that connects the power valves (part 18, 19, 20).

Remove the inner circlip (part 16) from valve 1, both circlips on valve 2 and 1 circlip on valve 3.

Remove the valve covers (part 3).

Remove the allen head bolt that holds the lever link to the shaft (parts 13, 14).

Slide the shaft from valve 1 towards the front (careful not to drop the washer (part 15) at the end of the shaft.

Slide the shaft from valve 2 towards the front and thru cylinder no.1 (careful not to drop the washers and the end of the shaft).

On valve 3 slide the shaft towards the rear (careful not to drop the washer).

There is one more allen head bolt that holds the valve in place against the cylinder (part no. 9) once this bolt is out grab a set of pliers and gently pull the valve out from the crosspin if you still have one. (or use two screw drivers to pry on the valve against the housing to remove it.)

If replacing the oil seal remove them from the end on the cylinders (Part 17).

See the following for some ideas on cleaning the valves – they will be dirty

Go to Tech Section / Engine / Cleaning Exhaust Valves

http://www.totallyamaha.com/

You will need to order 5 new circlips for the valve shafts and maybe new gaskets for the valve covers. A 2000 GPR uses a cheap paper gasket – replace it. Later models use a better gasket that some people have reused. With the oil seals it is the same situation, some people replace and some people reuse them.

While you are at it I'd strongly suggest installing a replacement power valve arm. The redesigned arm locks the pin in place. These arms are available form R&D.

R&D - Power Valve Actuator Arm R&D Part # 332-12003

good luck

[ 01-16-2003: Message edited by: Philip_GPR ]

isn't there somebody on the forum that is manufacturing some sort of 'fix' for the pv's? i know I saw a thread about it a coule months ago.