Cant reach max rpm's

[Cornnutt]

I've been fighting this problem since last summer. My 96 GTX has a weird problem. It wont go above 4-5K rpms until you hit a wave and get the impeller out of the water. Then it will rev over 6K until you let off. Some times you can get it to 5k then let off the throttle and quickly go full throttle again and it will rev, but not always. The impeller trick has been 100% so far. Then it resets again if you don't let off you can ride all the way across the lake running great at full throttle. I've had the carbs off 1/2 dozen times Im pretty confident they are clean and adjusted to spec. So far I've done the following-

Replaced all grey lines with new automotive black line
rebuilt the carbs new filters tried both pop off springs that came in the kit
new fuel selector valve
cylinders rebored and new pistons
new spark plugs
oil injection block off premix only
cleaned the raves and set per manuel
running with the choke on doesn't help makes it worse
Sometimes you have to give it a little throttle to start

Some ideas I came up with recently, but havent tried, have to wait till weekend to ride-

remove the gas cap and try to ride maybe a vent is plugged or ???
I haven't taken the gas tank apart and looked in there yet.

I don't know if either of those are on the right track. Seems like it would do it all the time if that is what was wrong. If the impeller gets out of the water the motor revs right up and comes alive running what I believe is 100%.

I'm willing to take it to the shop, but there isn't one on a lake close to me. I've explained my problem to the local seadoo dealer and they weren't very convincing they could fix it. They dont have any way to run it under load.

Any help would be greatly appreciated this thing is driving me nuts. Getting tired of chasing waves to get this thing to go.

 

[Dr Honda]

Sounds like the RAVES are opening too soon, and you are loosing torque. That's why, when you let off, and pop it open to full throttle... it will work. When you let off... the RAVE's close, and since the RPM's are still high... you can get over the hump.

Turn the the red adjuster knobs in the entire way, and see what happens.

 

[Cornnutt]

Thanks for the quick reply I'll give it a try this wknd and report back.

 

[Cornnutt]

Could it be the water regulator? I cleaned it last year and played with the adjustment. Didn't change anything it's set per manuel right now. I don't really know what it's purpose is.

 

[Dr Honda]

The water regulator can change performance... but it's not going to keep it from reving up.

 

[SabrToothSqrl]

I was under the impression the water reg was not adjustable? but the FSM says to check RAVES, plugs, RAVE selenoid, hoses, water regulator if not reaching max RPM under load... these engines will almost always reach 7k out of water (no load).

 

[Dr Honda]

The reg is adjustable. That's what the big red screw on top of the bellows housing is for. (same as the Rave's) Turning it in keeps it closed longer... and feeds the pipe water, longer. Once it opens... the pipe dries out, allowing higher RPM's, and the water is sent to the waterbox.

 

[SabrToothSqrl]

ok, it says "should not be" not "can't", unless you have a DI model.

Adjustment
The water flow regulator valve has been calibrated
at the factory and should not be modified.
NOTE: Water flow regulator valves ordered from
the parts channel are also calibrated. The valve cap
on the DI models is sealed and it is not adjustable.
If the maximum engine speed cannot be attained
or if the engine has poor performance, the water
flow regulator valve should be considered in the
troubleshooting of the problem.

 

[brock1]

if i were you i wouldnt run it pre mix youll burn up your rotary gears they need oil to lube them

 

[Cornnutt]

I left the oil tank in and only plugged the line that used to run to the oil pump. The tank is half full of oil for the rotary gears all should be fine with that.

 

[brock1]

ohhh ok good thinkin cuz ive seen lots of people burn them up and wonder why if they mixed the oil. Good job hope it all works for you

 

[Cornnutt]

Update- I adjusted the Raves all the way in. Made a little differnce last week at the lake the only way I could get it above 5K rpms was to get the impeller out of the water. With the RAVES all the way in I could get it to 5 then let off and snap back on the throttle and it would go to 6200. It worked that way for about half an hour then went back to having to get the impeller out of the water.

I also tried running without the fuel cap on that made no difference. This thing is driving me nuts. Could I maybe need a new water regulator?

 

[Dr Honda]

It may need a regulator. BUT... you can take it apart and clean/check it out.

Did you check the compression by any chance?

 

[Cornnutt]

I haven't checked the compression yet, but last year I sent the cylinders to SBT they rebored them. I got the platinum piston package and had them cut the RAVES for me. I took the Reg. apart last year and cleaned/looked over everything. Is there an easy way to adjust the cabs. Maybe if I play with the adjustment I can get it past the bad spot, but I think you have to take them off to adjust. Everything is soo tight in there for space.

 

[bigperm]

Well after cleaning and replacing, I am still having same problem. In need of help. Mine is exact same issue. On 97 GSX.

 

[Cornnutt]

Bigperm you replaced your water regulator and it didn't help? Does yours do the same thing with the impeller if you get it out of the water the ski will run good. Last weekend I had to go around in circles untill the waves were big enough that when I went out of the circle I would jump a little and get the impeller out then keep it tagged until I got where I was going.

 

[bigperm]

Does the exact same thing. I am going to check my impeller clearance. 110 degrees is just a little hot to work on it...lol

 

[Cornnutt]

Last season I replaced my impeller with a reman from sbt and the wear ring. Didn't fix mine, but I hope it works for you. I have a wedding to go to so I cant tinker this wknd :-( . I am going to try taking the fuel line out of the tank and clean what ever is there. I haven't had the tank apart yet. Let me know how yours goes. I'm getting low on weekends. This year didn't warm up fast so I will only have July- end of august most likely.

Good luck buddy

 

[bigJake]

The reg is adjustable. That's what the big red screw on top of the bellows housing is for. (same as the Rave's) Turning it in keeps it closed longer... and feeds the pipe water, longer. Once it opens... the pipe dries out, allowing higher RPM's, and the water is sent to the waterbox.

Doc, can you explain this: "Once it opens... the pipe dries out, allowing higher RPM's". I've never quite grasped the full concept of the WR other than (I think) it lets more water into the tuned pipe at lower rpms and less water at higher rpms? Thanks.

 

[brock1]

Doc, can you explain this: "Once it opens... the pipe dries out, allowing higher RPM's". I've never quite grasped the full concept of the WR other than (I think) it lets more water into the tuned pipe at lower rpms and less water at higher rpms? Thanks.

I believe it is so you dont get to hot. At low rpms the peipe will stay somewhat cool. But when you are traviling aT HIGHER RPMS THERE IS NOT SO MUCH OF A NEED for that much water being that you are typically moving pretty fast and the pip is cooling itself that way. That is the way that it was explained to me so if im incorrect please correct me so i know too.

 

[Dr Honda]

Doc, can you explain this: "Once it opens... the pipe dries out, allowing higher RPM's". I've never quite grasped the full concept of the WR other than (I think) it lets more water into the tuned pipe at lower rpms and less water at higher rpms? Thanks.

Well... that's exactly what it does.

OK... quick tuned pipe theory.

A tuned pipe helps the scavenging of fuel in a 2 stoke engine, and it all has to do with a pressure wave inside the pipe. So... if you want to build torque, you use a short, fat pipe... if you want more HP in the upper RPM's... you build a long skinny pipe. BUT... if you want both... you can't. That is... until someone figured out that you can change the speed of the wave with heat.

OK... so you ask, what does this have to do with water??? the answer is... Seadoo built a pipe for very good top end performance... but that left the engines with soft mid acceleration. SO... they added the RAVE valves to change the port timing... and the water regulator. They figured out that if you spray water into the head pipe in the lower RPM ranges... you can slow down the pressure wave, allowing for a much better mid RPM acceleration. But... they didn't want to loose the top end... so the water regulator, lets the tuned pipe dry out, and allows the pressure wave to speed up.

So... there you have it... the best of both worlds in one pipe.

FYI... it worked so well, that it was banned from Runabout Racing. (Because the whiny little bitches at Yamaha and Polaris didn't have that system from the factory)

 

[bigJake]

Thanks, I caught the gist of that, except for the underlying premise "if you want to build torque, you use a short, fat pipe... if you want more HP in the upper RPM's... you build a long skinny pipe". I know we are getting pretty deep here, but is that something you can briefly explain the physics behind? Sorry, but I get a much better understanding of the mechanics of something if I have a basic understanding of the underlying principles. I'm guessing that torque is somehow related to the backpressure of the exhaust and the frequency of the pressure wave and thus the presssure can be controlled by the size of the pipe (or as you also say heat). Kind of like the way the size of an ocean wave increases as gets closer to the shallower shoreline?

 

[Carguy89]

I agreew with teh regulator idea. I had a similar problem caused by a combination of that and there being a pinhole leak out of one of the bungs on the pipe, leaking water on the stator ever so slightly.

 

[boater454]

I found this site and thread while trying to solve the same problem you're having. It's also with a '96 GTX. I'll adjust the valves first and let everyone know what happens. Looks like this site will be great!

 

[Cornnutt]

bigperm & boater454 What have you guys tried to fix this problem?