2001 Yamaha GP 800 R power loss - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

Pink lightning · 08-06-2011, 01:44 PM

Help I have 2001 Yamaha GP 800 R top speed since I have had it only a few months has been 38 Mpg seems to start and Run smooth But first time I have owned PWC Neighbors son says it should do 60 MPH and my problem is
what he called SERVO MOTOR Assembly ? it is on the left side of motor as you sit it has a cable goes around a pulley and back to Servo Motor assembly
he says when you hit the throttle that 2 little pistons that you can see should move doing something to the exhaust and he says there is an electronic Part that is suppose to move pistons when you hit the Throttle but nothing happens does this sound like a problem anyone has Had with your Yamaha says it is an easy fix and that is why my Yamaha will not go Faster than 38 MPH any Help will be appreciated
Ernest T where are You!
Thanks,
Pinky

Ernest T · 08-06-2011, 09:52 PM

That's the power valve servo motor. Its what makes the PVs move. The power valves essentially change the exhaust porting for different engine speeds, which gives you more power. Problem on the early models (pre-02) is that the power valves tended to come loose and fall........sometimes into a cylinder causing major damage. The fact that your engine is running says that hasn't happened yet, but they may have fallen and not be working. Many times they just come off and drop, and cause no damage, but do result in power loss.

I think the top speed on the GP800 was around 56-57 when new. Keep in mind that the powervalves may only be part of your problem. I seriously doubt that a problem with the powervalve system could account for all your problem.........maybe 5 mph, loss but not much more unless a loose valve has also damaged the piston. You likely have other problems.......dirty carbs, worn out piston/cylinders, etc., may also be factors.

If it hasn't been done already you need to add clips to the power valves, or replace the power valves with ones with clips, and ensure that the servo motor and cable etc., are all working. Do a search on powervalves and you will come up with 1000s of posts. It is a very common problem on the early models.

Here is a guide on a 1200 for upgrading the valves: Shop SBT - power valve

More reading: WaveEater Products
WaveEater Products
Copied from another post:
PV service is not that bad. Here are the basic steps...

Remove the four bolts holding the PV covers.
Remove the servo cables from the pully.
Remove the center conection bar.
Remove the small allen screw that connects the PV arm to the shaft.
Remove the shaft out the rear and front of the cylinder. There is a small clip on the end of the shaft.
Remove the larger allen screw that holds the PV guide into the cylinder.
Pull the PV out of the cylinder. It will take a bit of force to pull the guide out.
Clean everything well and reassemble with locktite on the screws.

Purchase a set of new PV links from SBT or a set of WeedEater Clips to prevent the PV pin from falling out and droping the valve in the cylinder.

Also sounds like you may need a new servo motor. Check the electrical connections 1st. Very common to see loose/broken wires to the servo motor, broken cable, etc..

Pink lightning · 08-07-2011, 12:09 PM

Thanks T for all that information I will do more research as you suggested
so I Don't do any Damage to the Motor going to Clean the Carbs also not sure last time they were cleaned or Rebuilt. Will let you know how I make out with these problems. I did have one more Question I enjoy working on Yamaha myself but I am new to PWC Mechanics any Idea what it would cost if I took it to a Yamaha dealer and had them rebuild the Carbs and replace Servo motor and add clips ect

Thank you,
Pinky

Ernest T · 08-07-2011, 03:17 PM

Carb rebuild kits run around $50-75 depending on the carb. The rebuild is not that hard to do, but it does take time, and most shops charge high hourly rates. Most dealers in my area would charge $150-$200 per carb. for the rebuild.

An new OEM servo motor would run around $500, and it would probably cost another couple of hundred to install it and do the clips.

So for the whole job you could easily be looking at $1000+.

Pink lightning · 08-07-2011, 06:17 PM

Thanks T for the Quick response since I still have My 1992 Yamaha VXR 650
and it seems to be running Fine. Think I will Try to rebuild the Carbs and maybe replace Servo motor and clips ect on my own and take my time.
I appreciate all your Help will let you know how I make out. Very short Pwc
Season around here.
Pinky