2001 800GPR bogs on accelleration

[Rogaty17]

Hey everyone.
I have a 2001 800GPR that i bought couple months back from a guy that said it had a low compression on #2 cylinder. So me and my buddy rebuild the whole top end, both cylinders, both new pistons, rings, ext, new powervalve eaters. It also has a aftermarket prop "solas", with a bigger pitch. When we took it out on the water and hit the gas the ski would start to pickup rpms but would not go forward. So we intalled a plug kit from riva to prevent cavitaion. Back on the water again. When i hit the gas, the ski would start going slow, about 10 rpms for about a 1min and then slowly picks up speed, and than at about 20 or 22 rpms the engine kicks in and accelerate right away like it's about to throw you of the ski. Same thing would happen when i go jump the waves. The ski will not take off sharp until i jump a wave and the engine would kick into high rpms and will throw me off the ski. I reinstalled the original prop and still is doing the same thing. When we had the carbs off, I didn't rebuilt the carbs but took out the low rmp needles and cleaned them out and reinstalled the needles to factory setting, same amount out before we tooke them out, but left the high rpm needles intact. What should I do next? Should I rebuild the carbs from ground up with the rebuild kit from SBT? Please help... I want to ride my ski couple of more times before the end of summer. Thanx for any help.
Mike

[Technical Support]

Re: 2001 800GPR bogs on accelleration

When you hit the gas does the rpms rev high but the ski doesn't move? Or does the ski bog down and then pick up and move?

[Rogaty17]

Re: 2001 800GPR bogs on accelleration

The ski bogs down (feels like it doesn't have power on low rpms) and then picks up after good 30-60 seconds, or when i jump the wave the ski picks up the rpms and rides fine on high rpms.

[skisol]

Re: 2001 800GPR bogs on accelleration

Carbs most likely need a rebuild.

You also have an accelerator pump, which does not seem to be working.

I would go thru the carbs, if I was you, so make sure that the accelerator pump works and injects into both carbs.

In your case you might want to get rebuild kits, I have the advantage that I got each individual part for carbs, so I only replace what need to be replaced.
That does not help you so get rebuild kits.

[Rogaty17]

Re: 2001 800GPR bogs on accelleration

I took apart the carbs with my buddy and sure the accelerator pump was sticking, it would go in but not release. My buddy took the carbs into his work and took them apart and said that there is a lot of junk in the carbs and tried to take out the "high" screws and broke one off. Now we are waiting for the tap tool to come in the mail so we can rethread the hole and rebuild the carbs. We'll see this coming up weekend.

[Rogaty17]

Re: 2001 800GPR bogs on accelleration

Hey i just rebuilt my carbs, and took it out on the water and it was still doing the same thing, but!!! While i was testing the ski without the seat i noticed that the power valves were not moving at all. I turned the powervalve cables the opposite way than they were and it fixed the problem. I ordered the powervalves motor and installed it and took it to the lake. The ski takes off like a rocket but it cuts off at 35 or 40 mph. It feels like it does not get enough fuel. How is it that when the powervalves were bad i was getting top end and now that they work i don't. I did cleaned out the needles for the high and the lows and reset them to the settings from sbt tech. Please help me. I want to get at least couple more runs out of this season. It was nothing but problems to me all summer.
Thanx

[skisol]

Re: 2001 800GPR bogs on accelleration

If you say it cuts off, does that mean that the engine shuts off completely?

With the powervalves working it should still hit to speed, the only other thing you touched where the carbs, I don't know how you got the broken adjuster removed.

It can be as simple as what I had a couple of weeks ago, I rebuilded a carb, ski did not get to top speed, what can that be, ok lets take the carb out and double check, took the bolts out and sh.. the gasket had slided down so it covered a part of the intake manifold.
Stupid however we all make mistakes, placed it the way it should be and run like a champ.

So if you are sure that the valves operate perfect I would go back into the carbs.

[Rogaty17]

Re: 2001 800GPR bogs on accelleration

We took the carbs apart to adjust the springs to get the pop of pressure. With the old springs, the pop off pressure was at 70 psi. Changed out the springs and got it to pop between 50 and 55 psi as per sbt tech. Took it out on our lake behind the house and the ski ran good for the firs 3 runs. First run 48 mph, no problem. Second run 52 mph, no problem. Third run 57 mph no problem. On the 4th run the ski started to cut out again at 52 mph. Cutting out, I mean, it does not shut down it just feels like it was starving for fuel. It would go between 48 and 54 mph cut out for a split second and go again, and it would get worse as we kept on riding. Brought it over to the trailer took out the plugs and it showed that they were running a little lean. Today I was going trough the parts diagrahms on the internet looking for the stickers for my ski and came across the fuel line picture. We had the fuel lines hooked up backwards. Swapped the lines, started the ski up in the garage. It ran fine and sounded fine. Took it out to the lake and it would not start. Brought it back to the garage took out the plugs and found the back one cracked at the porceline. Replaced the plugs with some other used ones and still did not start. My question is " if the lines going to the carbs are swaped, should it still run or not"? (it ran in the garage, started the ski 3 times without a problem) and now no joy. Do you know where is intake/pressure and which is return on the carbs so i can get my lines straight. THanx

[skisol]

Re: 2001 800GPR bogs on accelleration

It will run on your return line, up untill the fuel is out of it.

The lowest line closest to the bottom of the carbs is the in line.
The line above is the return line.

Are you also sure that there is no water in the gas?

Are you sure that the rebuild on the carbs is done 100% perfect.

Out of how many holes within the carb bodies did you see liquid coming when you checked your lowspeed section to be clean and not clogged up.

Many people make the mistake and think that they have a problem at the high speed section when they don't hit top speed, 99% of the problems is caused in the low speed section which is also part of your fuel management at high speed.

Sorry for the word fuel management, could not think of anything else, however that is what is happening in a carb.

Rebuild kits, I don't know about the ones that you used, however in the passed I had major problems with Winderosa, the highspeed check valves where thicker than the OEM Mikuni, which gave me sometimes trouble mostly in single carb setups.
However sometimes is to much, I always use OEM Mikuni and never have had any more problems.
The highspeed check valves gave me the same trouble as you describe, however there are more options.

I still believe that you have a carb issue, since everytime you do something to them things are changing, now I don't want to be nasty, but does the person who is doing the work on them understand these carbs?
Just so you know, you might be thinking that you got it fixed if you run your topspeed and than O O it slows down again, now the engine is blown, why? Because of the carbs not being rebuild proper.$$$$$$

[Rogaty17]

Re: 2001 800GPR bogs on accelleration

Back into some warmer weather in Jacksonville. Back with the same problem. I'm running out of options here. I got all the fuel lines connected correctly. I ordered some carbs from 99 yamaha 800gp. I looked at them and asked about it if they are the same model. I compared them to the diagrams on the internet and are the same type and model. I replaced my old carbs with the 99 yamaha ones. I left the needle settings as they came, not sure what they are set at. Took it out to the water and it still has the problem. The ski accelerates fine up to 42-48 mph, but with the throttle opened at half way. Once i get up to 42-44 mph and try to open the throttle all the way it will try to bug-cut down. It will not bug down all the way it just feels likes it still starving gas at full throttle (more than 6000rpm's). Once i let of the throttle to half way it will go between 42-48mph. I'm running out of options here, and i don't want to rebuild the carbs again cause it gets expensive unless i really have to. My next step is to take carbs apart and look them over again for missalligned gaskets or something. (but the guys said it came of a running ski) How would my ski run with the same problem with different carbs. I just don't get it. Is there anything else that can be wrong with it. PLEASE HELP ME.
Mike