2004 GTI LE RFI bogging down then takes off like a rocket.

[Kris69]

Hi all!

I'm Kris, a newbie here to the jetski fraternity

I have a 2004 GRI LE RFI that has a bogging down issue between 2000-4200rpm at full throttle then it will suddenly try to accelerate and cavitate (upto 7000rpm) a bit then shoot off to 6400rpm tops at speed. Runs fine when at speed and idle fines too. I bought it knowing it had some issues.
Have put in a new voltage regulator and battery so far but still only getting approx 13.2 volts. To scared to free rev to 6000rpm as suggested.
Haven't done plugs yet.
Have removed and cleaned one RAVE valve but couldn't remove the other one completely as it hit the exhaust pipe/chamber.
I have found a few similar posts which have said to do a compression test.
What figure should it be? Warmed up or cold?
Still need to test the RAVE solenoid too.
Can anyone help point me in the right direction for testing please?

Cheers

Kris

 

[JCJ256]

Sounds similar to a lean hesitation with a carb system, perhaps a bit different with an injector model. Have you checked the injectors?

 

[jammin777]

check the compression engine cold. i had a similar issue, 99 gsx rfi) the rave were open all the time which will cause the bog at low- mid rpm's.
the fix, replaced the cheap after market rave bellows (stiff and held raves open) for the more pliable oem ones.

 

[Kris69]

Thank you JCJ256 and jammim777.

jammin777, do you know the approx reading i should get? I can`t find a value anywhere in the worksop manual. I`m still trying to figure out how these RAVE valves work! I know they get pressure from the crankcase to the underneath side of the bellows but i am assuming they should be sealed in some way to allow the pressure to build and lift the valve but it doesn`t look like it does?
How far down should the red caps be screwed in too? Any tricks to remove the MAG side RAVE? It interfere`s with the exhaust pipe.
Cheers

Kris

 

[JCJ256]

Kris,
Yes, RAVE's can be a bit of a mystery at first. But while the science of how they help unlock more power from your engine is somewhat complicated, the mechanics are actually fairly straight forward.

Crankcase pressure is directed to the bellows chamber (yes, it is somewhat sealed) via either an external tube, as with your engine, or an internal passage, as with my older carb'd version. The valve is held down in the CLOSED position (not really closed, just somewhat restricted) by the spring on the top side of the valve shaft, just under the cap. As the pressure increases, it eventually overcomes the spring tension and allows the valve to fully open creating greater exhaust flow. The spring tension is adjustable via the red button on the top cap - screwing the button in increases the tension thus delaying the valve opening - and adjusting the button out of course the opposite. There is a 'sweet spot' of course with this adjustment. If the RAVE opens too early it may feel like you've hit the top of your power curve well before your top end. If the RAVE opens too late, you would likely experience bogging or hesitation in the mid to mid-high RPM ranges before the intake flow 'catches up' to the exhaust capability. Tech manual says the timing should be perfect, but functionally speaking, from a tuning standpoint, it is better to start with a setting that allows the RAVE to open a bit earlier and water test the craft, slowly increasing the spring pressure till the power curve feels constant, and just before the bogging & hesitation begins. DO NOT screw the buttons all the way in, or out, when starting the process. I would suggest somewhere just light of center - usually where the red cap is protruding just slightly past flush from the cap surface.

I don't know exactly how your system works using a solenoid. It may be a transition between the crankcase and RAVE to reduce or eliminate the possibility of oil clogged passages, as can occur with the direct passage system I have. The end result and mechanics are ultimately the same.

As for removing the RAVE on the MAG side, you have to disassemble the valve in pieces, and reassemble in the same manor. It's a pain, but the only way without removing the exhaust manifold & pipe. First, remove the RAVE cap, making sure to trap the spring so it doesn't fly across the room. You're now looking at the RAVE piston, which has a hex (10 mil, I think) in the center. The rubber bellows should have a small zip tie or spring clamp at its base and another larger spring clamp (looks kind of like an O ring) at the top, securing it the the piston. Remove the top spring, unscrew the piston (counter clockwise) and separate the two. Then pull the bellows from the housing base. You should now be able to remove the RAVE housing separately, and then the valve blade itself. Reinstall in reverse order.

TIP: After reinstalling the valve blade and housing, secure the bellows to the housing base first, then screw the piston on. There should be a small amount of grease (manual states MolyKote, by DOW) around the rim of the piston to aid with seal and also helps with installation. This should make it fairly easy to slip the bellows back over the lip of the piston. Be careful when reinstalling the spring "O" ring that you don't dislodge the bellows seat. These springs can actually be more of a pain to install than any of the previous steps, just be careful not to over-stretch them.

 

[jammin777]

the way i found out about the raves being open all the time is that i popped the rave cover off the slowly put it back on seeing if the spring tension would close the rave but it did not. the rave should close in the downward position.
at first i thought the springs were too weak and tried new ones but didnt make any difference. sooo, i thought i still have the old rave bellows (replaced with new cheap aftermarket when i rebuilt the engine for preventive maint) i installed the the old ones which are oem and it took care of the horrible bog from a standstill to 5k rpm's. then it would take off as you say, like a rocket. it ran like a scalded dog with the oem bellows throughout the rpm range.
on the rfi's most would run the red cap - rave adjuster about a nickle deep screwed in which is the way i had mine setup.

 

[Kris69]

Thank you guys so much for all this info! Very much appreciated
I have since put new plugs in, done a compression test (both 160psi) pulled out the fuel pump to check and clean the fuel filter. Boy what a job just getting out the air tube!
The spring seems to be pushing down the bellows after i cleaned/removed one completely and pulled the other one up as far as i could with the lid off it. Will pull apart the other one at another stage.
Just need to get back out on the water to now test it.
One question i have. Is there an injector cleaner available and safe for 2 strokes on the market? I read in the manual not to use one but wondered if one is available and safe to use?

Kris

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