[lfm]

So how does the exhaust valve hit the piston (it has in some cases, I've seen pictures)? more

[silverkknd]

If you own a 2-stroke Yamaha PWC with exhaust power-valves and you have done any research at all, there are known issues with the exhaust valves. There is even a couple different after-market fixes for it. First, the background: the exhaust valve is actuated with a servo driven shaft that pivots an arm which moves the valve up and down, the connection between the arm and the exhaust valve is a press-fit pin into the cast aluminum exhaust valve (that is the shortened explanation). The issues (that I am aware of): 1. the pin comes out of the exhaust valve and the valve falls (most common) 2. the valve actually breaks at the neck and the flat part of the valve falls.

[jinnyh345]

This was the information I had right after I bought my 1999 GP800X with 185 hours about three weeks ago. After researching and finding out how hard it was to remove the exhaust valve covers with out removing the engine from the hull (the 1200 is much easier from what I understand) I decided to throw caution to the wind and not do anything with the motor. Due to the previous owners not properly winterizing the machine, a crank bearing went out so I was forced to rebuild the motor and I decided to fully explore all my options with the exhaust valves. Here is what I learned from the disassembly: the exhaust valves slide in a machined slot that has a bottom to it (see picts with valve removed). An exhaust valve that is not worn out or broken will not hit the piston on a stock bore cylinder even if the pin has come out because it will hit the bottom of the slot before it hits the piston. This is proven in the pictures. I slid the valve into the cylinder with the arm removed and there remains clearance between the cylinder wall and the exhaust valve (see pict with straight edge), however this clearance is not very much (may be 0.020" or so I couldn't get a feeler gauge in there). If you have bored and replated you cylinder this clearance will be much less.

[ehaileyyatesn]

I am going to install the waveater clips on my rebuild but not the billet valves because they are about $130 per cylinder. Knowing what I know, if I owned an untouched 800 power valve motor I would not do either of the aftermarket fixes. I would just make sure that the valves have not dropped and check them at regular intervals, maybe every 10-20 hours. I am not sure what the best way is, but one possibility is to take out the spark plug, shine a light into the cylinder and rotate the drive coupler until you can see the exhaust valve. Then disconnect the cables from the shaft and rotate the valve shaft. If you can see the valve moving up and down, you should be good. here

[nicoleblair112]

2. Push the coupler forward and pull up and off. here

[mrchantcashadvance]

Designed as an added measure of security when retaining the OEM Powervalves in Yamaha engines. Fitted clip prevents pin for moving and valve from dropping to low into valve guide. Special couplers better synchronize valve actuation through tighter tolerances and improved design.

[Waterfox]

3. Install new WaveEater CouplerSlide on the small end of the spring then the stainless washer. The washer keeps the slotted shaft from spreading apart. Push the washer and spring on as far as it will go. Next, angle the coupler and slide on the flat end of the coupler over the long slot in the power valve shaft. [links]

[aksjfhasdkfjh8]

Instructions:
1. To remove the original couplers pull the black plastic clip off of the power valve shaft. We will not use the black clip when installing WaveEater couplers.

[todu]

4. Line up the pin with the mating shaft and slide the WaveEater Coupler back into place. This will be a very tight fit and may take a little force to lock into place. The spring holds it on.

[memen]

Past:
2000 Yamaha GP1200R
2004 Honda R-12X with Macboost stage 2 here

[allinvain]

Current:
2003 Kawasaki SX-R 800 with FP wet pipe
2006 Sea-Doo RXP (stock)
2006 Sea-Doo RXP (minor mods)

[UndeadCircus]

But, for $20 per cylinder, they make the power valves a non-issue, if not, convert them to a beneifical issue ! [links]

[songcopy65]

Past:
2000 Yamaha GP1200R
2004 Honda R-12X with Macboost stage 2

[TORNS]

Ya, you cant do anything to the 800 motor without removing the exhaust. That motor is the biggest pain in the butt to work on and I've worked on everything but Polaris.

[bobsled]

:agreed: The ZZR1200 is a tank. thats why i bought the Blackbird. [links]

[alowm]

I know I shouldn'be saying this here but.
Bandit 1200 naked 2001 :knock:

[peex71]

The KTM was a blast though (no honestly) more

[8668]

the rear wheel was slightly buckled & the drum break was warped, the front disc was polished stainless & at the merest hint of moisture all thoughts of stopping went right out the window.

[Psychoactive]

Worse bike I ever owned was a clapped out Suzuki 250 Husler I bought for $50. The front wheel bearings were shot and the the wheel had 1" of slop from side to side. Handling was "interesting" to say the least. I bought it at a pub as a "doer upper" but ended up riding it for only 3 days before I flogged it to a work mate as a "parts bike".

[Dave Kimble]

Even the 'umble C90 is a bike if that's all you can afford at the time. :whistle: more