How to service Rave Valve---Pictorial---

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I had a chance to check mine today, the one that was spitting oil was missing the spring that fastens the below. I order some new parts and cleaned up what i could. Hopefully that should be the fix thanks again
 
3 cans of spray and those bugs still run around my screen.They must be on the wrong side of the Windows:)
 
Found this thread very helpful and easy to follow. It helped clear up a bunch of questions i had about the rave system. Hope me replying moves it up on the list so other newbees can see it. Thank you again and i will keep reading.
 
Rave Valve and top end rebuild

Doing a rebuild on my 787. Using .5 oversize. Instructions in Piston box: "when installing any piston .5mm (.020) or larger, you must file down your Power Valves (rave valve) .015 Thousands.... Failure to do so will result in SERIOUS DAMAGE TO THE PISTONS.

How do you file down the rave valve evenly to .015? My auto shop won't do it.


I was thinking of using a finishing sand paper 600 grid or so attached to an old piston to get the correct curve and us this as a way of removing .015.










seadoosnipe said:
RAVE is acronym for "rotax automatic variable exhaust". It is patented and is why the 787cc is capable of making 110hp, for such a small engine. In the days I built high performance 327 and 350 cu.in. motors, all my friends would brag about how they just bought a 650 or 850 cfm Holly carb and was going to beat me come Friday's race. I had a simple 4 barrel quadra-jet at the time. No frills, no big money. But, I did remove my 1:98 heads and went to the 2:02 heads. This gave me a larger exhaust port. The theory is, if you want to burn more fuel, you have to be able to exhaust that fuel. No matter how much fuel you dump in an engine, if you can't exhaust the expanding gases, then your not making anymore power.

The RAVE design is set up so that when you increase throttle, building rpm and horsepower, the exhaust pressure increases through the internal porting of the RAVE housing pushing up agains't the spring tension of the bellows, overcoming it and opening the slide valve. As the slide valve opens, it makes the porting large enough to exhaust more gases. This is where you get the extra rpm and horsepower.

The reason we clean them is simple. The 2 stroke motor mixes oil for lubrication of the roller bearings in the crank, wrist pins and main bearings. Most all the fuel is burned off in combustion. The oil we use is a low ash, which means it does have some carbon exhausted. The slide valve is the first moving part that comes in contact with that carbon (soot). It will build and gum up the slides for your guillotine valve, causing it to stick as it's trying to open. If you've ever been on the water and when going to WOT, there is a hesitation between 4 and 6K rpm, that's usually due to a sticking RAVE. If it's bad and your on the water, you can back off your red caps a few turns. This will alleviate the sticking, but don't use that as a reason not to clean them.

I would like to make one quick statement. The RAVE guillotine valve is easily cleaned with brake/carb spray cleaner and a piece of wood stick. I know everyone has their different ways of doing things, but whenever you use a piece of metal to clean another piece of metal, always make sure the metal you are using to clean with, is of a softer type. For instance, the RAVE slide valve is made of aluminum. Use copper or brass to as your wire wheel. Don't use a Stainless wire. You will not only be removing the carbon build up, you'll be removing the aluminum metal of the slide and in a few years, it won't fit the grooves anymore.
Click to expand...
 
You could take it to a machine shop who deals in high performance parts, they should do it.

But, though the 787cc motor is stock with a bore of 3.228" and recommended for a bore over of .10 (3.238"), it's not recommended to bore over .20". If you do, you will need to shave your guillotine slide valves. Since it's not a huge amount and there is a small amount of tolerance, I don't see why you can't do it yourself.

If I were going to do it, I'd take an old piston, lock it down on my workbench, then use it as a jig to grind my slide valve. Hope it works out for you........
 
Newb

This thread is extremely helpful considering I didn't know what a RAVE valve was until a few days ago.

I drove down to Michigan City Indiana and bought two 1996 Seadoo XP on a double trailer for 3K on Sunday, VIN#s say their a matched pair. A and B. That oddly enough were originally purchased from Lake Orion Michigan which is where I live. They have returned home hahaha.

So anyways, These are my first ski's, They both started on a dime when the old owner fired them up for me. When I was inspecting the hulls and engine bays I noticed that one of the RAVE valves was leaking oil, But at that point I didnt even know the lil red caps were valves.

So I got home and started bouncing around forums learning about this setup, How it functions and what maintenance was key to keeping a reliable machine. First off, I know nothing about 2 stroke motors. I never owned one. But I have a lot of experience in auto so i'm diggin right in to it.

I just pulled the leaking valve housing off and that little 10mm plastic nut was melted inside of the spring. There was the red rubber, bellows? (I need to figure out the names of all these parts) with a spring around it that looked to be ok but the rubber black piece is damaged its hole is melted and reamed out just like the picture in post #40

I went ahead and removed the two alan bolts and separated the lower housing from the head. The gasket looked to be in good condition. On closer inspection I remembered there was suppose to be an O ring somewhere, But Its not there. Im looking at this groove that looks like there should be an O ring there and there's not. Maybe it got melted away? Hahaha.

I want to rebuild and clean all of these, The amount of shit thats on these parts is epic compared to the OP pictures. I went in with no rubber gloves, I wont be doing that again.

So whats the deal with the RAVE valve on the exhaust? Should i go ahead and rebuild that too? If I did, that would make 6 that I have to do. I noticed SeadooBuddy mentioned MotorCity Powersports, I drive by there every day. I'll try them first for the rebuild kits.

Im going to start my own thread with pictures so I can go over everything, Not just RAVE valves cause summer is fast approaching here and I wanna ride! Which means I gotta fix these fast! Michigan has had a streak of 70s and 80's for the past two weeks and I got the fever!
 
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I have a 2000 RX and decided to clean the RAVE valves. I took the first one out with ease and quickly sat it down not paying attention to which way it went back in. I figured I could look at the 2nd one to figure out which way it went back in but now I am questioning myself thinking they could go opposite ways. I am going to take them back apart tomorrow and i have read they may be stamped with TOP on them but since they are vertical, which way is top? Thanks guys. As of now, i have them both the same way (the concave of the valve)
 
it's marked "TOP", that side faces the pistons.

this is post #3...
Yeah its not really the best write up but I hope it will help someone....On a side note, it's very very important to put the Valve back in facing the right direction....mine is stamped TOP on one side, and that it the side that should be facing the pistons.
 
The side marked TOP faces the spark plug, the side with the double notches faces the piston, the bevel is down. This is what they should look like when putting them back in, the notch on the base must face the exhaust manifold. When you install the raves you should be able to read the word TOP.

Lou
 

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RAVE Valve damage

I need an opinion from you guys.

When I pulled this RAVE valve, What they call the "Exhaust Piston" was melted and by the looks of the RAVE it had just been dancing around in the cylinder because as you can see the edges are slightly bent and theres aluminum burrs on the edges. The burrs are hard to see in the pictures but if I use this RAVE they definitely have to be filed off.

On the TOP side theres seems to be more wear on the edge than the 3 others I pulled. Question is, Should I reuse this RAVE or get another one? I have the rebuild kits but i'm not sure if I should reinstall this or not?

That 3rd picture has a sharp jagged edge,while all the other RAVES I have are smooth on the edges, not sharp.
 
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Joe it
Looks like someone shaved them down for oversize pistons. I would pull the head to make sure if you put new ones in with out shaving them you will damage your pistons.
 
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Well I pulled mine out and neither side has TOP stamped on it. Also both sides are smooth, no grooves. Both valves are identical
 
Since you have a 951 they are a little different. I couldn't find any pictures on this site but I did find a pretty good pictorial. The 951 rave valves are not marked and maybe it doesn't make any difference which way they go in, I would do it like this pictorial shows. The beveled side goes toward the engine, the flat side toward the vacuum connection.

http://www.theudells.com/PWC/other/rave/rave.htm

Lou
 
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Dang Lou i was looking at your link. Man what kind of oil was he using? must have been some cheap oil.
 
Ninetok said:
Joe it
Looks like someone shaved them down for oversize pistons. I would pull the head to make sure if you put new ones in with out shaving them you will damage your pistons.
Click to expand...


Does it really look shaved to you? To me it just looks like the others I have, Like they have been wire wheeled ten thousand times.

I never thought about these motors being bored over from a previous rebuild, That messes my whole world up.
 
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The margin on the end just looks a little wide to me I cant really tell but mine don't look that wide. On my other ski it was bored 1mm over and looks like yours. One way to tell is to pull head and see if pistons are marked won't hurt any thing to make shure before you put new ones in.
 
Thanks Lou. I got her back together. I have moved on to the impeller pump oil. Got it all cleaned up and ready for new oil. What weight should I use? I have 75w-90 synthetic. Will that be sufficient?
 
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