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97 GTX woes...

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Johnson8537

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97 GTX woes... No TOP END

I have searched but did didn't find anything under what i had searched.
sorry if this has already been discusssed.

I have a 97 GTX.
Usually i ride my other ski until they are both warmed up but decided to ride the big 3 seater today to start.

Well after idling for about 5 mins waiting for my brother in law to return from parking we set off. idled out fo the no wake zone and then attempted to take off.
eased into WOT and took off fine (flet a little sluggish) but then hit 25-30 MPH and stopped accelerating. would not accelerate past that MPH RPMs were up to around 7K if i remeber right... Almost felt as iff there was a load behind me dragging.

1. I took it to the dock and changed lanyards just in case... same thing .
2. On the way back tried feathering the throttle and then all the sudden at 30MPH it took off like normal and went to full speed 55ish.
3. The rest of the day no matter what lanyard... would accelerate semi quickly to 25-30 and then almost as a powerband would take off again up to full speed.

I Changed the plugs about two times out before... i checked them and its getting oil and the plugs look great. ( I did not check gap before install).

any Ideas???? thanks in advance guros.. (I am two stroke stupid)
 
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For the case where you are at high 7K rpm revs:
Check that the reverse gate is adjusted correctly. The bracket could be broken/damaged and the gate (bucket) is flopping around. Essentially you could be in neutral when you rev it up.
 
That is the clamshell you are speaking about correct? that covers the jet?

(It could have been less rpms but i thought it was pretty high 6-7K)

Any idea why it would take off at 25MPG and not have the same type of acceleration from the start? I would think at 25MPH it would be plaining way before then.. but maybe that could be the issue. Heavy boat not plaining until about 25MPH and then able to use the power the just give..???
 
RAVE valves. The black and red caps on top.


A pair of hex screws hold them on to the engine. Clean them out so they don't try to stick during the transition under revs.
 
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JPX said:
RAVE valves. The black and red caps on top.


A pair of hex screws hold them on to the engine. Clean them out so they don't try to stick during the transition under revs.
Click to expand...

i'll give that a shot... do i have to grease them up before reinstall or just wipe them down ad put them back in?
 
Here is some info on the RAVE valves;
The RAVE, (Rotax Adjustable Variable Exhaust) valves are located above the exhaust valve. There are 2 of them per engine. They are round with a red adjustment screw in the middle. It has a clip that holds it together. How they work is that they open the exhaust port larger as the engine rpm's increase. When the rpm's drop down so do the RAVE valves. They work on the principle of the pressure of the exhaust system. Rpm's increase, pressure increases and the valve opens, rpm's drop pressure drops, Valve closes. They should be de-carbonized annual. To disassemble the rave valves, remove the spring clip on top, remove the black cover. There is a spring under the cover. Remove the piston by turning it with a metric socket. On the bottom of the piston is the rubber "Bellows" be careful with the small retaining spring that hold the bellows on the piston. Remove the 2 allen screws that hold the base on the cylinder. Remove the base and gasket. The long valve won't fall in the cylinder just pull it out. There is an o ring under the base, on the shaft of the guillotine valve. Be careful to see how it came apart as it has to go back together that same way again. On the base, notice the notch that it is facing down. Clean all the carbon off the guillotine valve. I use carb cleaner and 400 grit paper. Check the bellows for any small pin holes. If so replace it. If not, reassemble it on the clean guillotine valve, and install it back on the engine the same way it came apart. The guillotine valve only fits one way. The one closest to the exhaust pipe will come off differently then the other one. You will have to remove the allen screws and turn the base so it clears the exhaust pipe. I would do one at a time in case you forget how it goes back together again. This way you can look at the other one and copy it. Do both engines 2 per engine. Take your time and if you have questions give us a shout. We'll be here to help you out.
If the RAVE valves are dirty it will not rev up correctly and could be causing your problem.

The adjustment knob (the red cap) should either be screwed all the way in or flush to the top of the black ring of the cap. This will only affect performance, as far as how it jumps out of the hole or how well it runs for extended periods at WOT.
I hope this helps. Keep us posted.

Karl
 
Just cleaned the RAVE valves...
Boy were they sure sticky and had a ton of carbon build up. I cleaned them up and reinstalled them... started it up and seemed to rev up better. (probably in my head..) I'll keep you posted when i take it out again if the acceleration is smoother.

Could these have made teh ski not go over 25-30 mph until they got moving and unstuck?
 
i don't think it is RAVEs he has his rpm's. i think he has something in the pump or a problem with the pump. i'll catch a glob of seaweed and it will act just like that. then it'll suck the stuff out and go just fine.
 
derek said:
i don't think it is RAVEs he has his rpm's. i think he has something in the pump or a problem with the pump. i'll catch a glob of seaweed and it will act just like that. then it'll suck the stuff out and go just fine.
Click to expand...
:agree: If rpms are at 7000 and you are slow it will be some sort of cavitation.
 
You haven't run it yet after cleaning the RAVE valves...let us know after the trial run and it's behavior.

Karl
 
i had one do the same thing and the customers had tried to fix it themselves
and had some how put the rave valves in up side down and his auto mechanic friend rebuilt the carbs and left one low speed screw about 7 turns out the other low speed at 0 and both high speeds at 3 and i wonder why it would not pull a greasy string out of a cat tail
 
boatmonkey82 said:
i had one do the same thing and the customers had tried to fix it themselves
and had some how put the rave valves in up side down and his auto mechanic friend rebuilt the carbs and left one low speed screw about 7 turns out the other low speed at 0 and both high speeds at 3 and i wonder why it would not pull a greasy string out of a cat tail
Click to expand...

Mine were so carbony and greasy that they could not be read (TOP) until i cleaned them up..

I put them in the same way they came out... TOP facing up when reinserted.
 
I believe Robin didn't read the post correctly and mis posted. That's called an OOPS! It happens to most of us humans from time to time.

Karl
 
Originally Posted by robin savell lloyd
If rpms are at 7000 and you are slow it will be some sort of cavitation This statement was true but did not pretain to your probblem because your ski corrected it self as cavitation will not normaly correct it self Originally Posted by robin savell lloyd
 
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