Another Rave Valve question...

[TheYeti]

I took out the Rave valves last night and cleaned them up. I found them both really built up with hard carbon so I guess they were due. Got the boat last year and only had it out once for an hour or so testing it. Getting it resdy to test out this year now. I found one valve to be ok, all rubber seemed ok the o-ring was old hard and cracked and spring were all there. The other had no o-ring and the beveled adge had a slight bit of a lip on it. Not sure if that could be from a missing o-ring or not affecting the travel? Anyway it all wemt back together for now but the thread on the end of one ohe guilitines were basically stripped. So I had to wrap it repeatedly with thread tape to get it to start enlugh to where it would actually start threading wnough to hold together. My question is do I need to buy a new guilitine or what do I need to do here? Also if I need a new one how do I know which one of the many part #'s I need.
All I know is the boat is a 1997 Seadoo Challenger with a single 787 rotax
Btw I did replace the o-rings as I had an o-ring kit and had some that seemed to fit just fine on the shaft.

 

[POPPS]

Pictures please.

 

[TheYeti]

Sorry popps busy guy lately I guess. Here I am looking for help and holding up production. SMH. I'm just going to supply every picture I took that evening and sadly I'm not positive the one in question is going to show clesrly what I mentioned...

 

[TheYeti]

And a few more

 

[TheYeti]

Ya I don't think I have the oic of the one I was talking about. Not sure where that pic went. Everything did seem to clean up alright though. It was caked on good. Had to use a wire wheel to get it off well. Didn't change my issue with the throttle though

 

[TheYeti]

Well I feel like I shouldn't have touched anything until after testing my first fix. Rebuilt the carbs over winter and changed the pump oil (found what looked to be grease in there, but refilled with oil), then cleaned those rave valves. Took it out today...
Keep in mind I bought it last year at the end of the season. Took it out once and it had a carb issue so just did the rebuild and reset the screws to where they are supposed to be. Starts and idles fine first try now. When i drove it last year it would slowly build up to get to too speed but would plane high and pretty much 'catwalks' through the water. Now I take it out today and it idles fine put it in reverse or forward and it will idle in either direction, but throttle up a bit and it does not want to go at all. It will rev up all the way to 7500 or so and then i put it back down to idle. At one point I shut it off for awhile to let my daughter fish and it didn't wakt to start back up. Eventually it did after trying awhile. Not sure if maybe I shouldn't be sitting in the water not running with these things? It's my first Seadoo boat (first Seadoo anything). So before I introduce the next more obvious problem that happened. What could this be attributed too? Quick google search and the first reply is wear ring. But I don't just want to order that take the family to the lale again amd still have an issue. Any thoughts opinions?

Just realized I should probably post a new thread as this isue might not be related

 

[wernerml]

I don't see the springs in your pictures. Are they missing or just not pictured? Missing springs would cause the RAVE valves to actuate way to early at lower RPM which would make the boat sluggish at mid speeds then suddenly take off like a bat when it finally gets going.

Did you clean the passage from the exhaust port to the diaphragm? It runs thru the cylinder as a ~1/8" hole to the side (diagonal) of the valve body. There are four smaller holes in the gasket so no matter how you install it, the hole from the exhaust port is connected to the hole in the RAVE valve. The pressure from the exhaust must travel through the cylinder block, through the hole in the gasket, possibly around the curved passage on the valve's mating surface and up a hole to the back side of the diaphragm. If any part of that passage is blocked the valve won't actuate, and your peak RPM will be lower.

There is a lot of clearance around the guillotine, they should slide in and out of their passage pretty freely. The shoulder on the valve keeps them from going in too deep. The slanted end of the guillotine should be parallel to the side of the piston/cylinder.

If the RAVE valves are not actuating you get lower RPM (5000~5500) and the boat won't get on plane. You might be able to get a lightly loaded boat on plane, or try moving a small passenger to the front seat to push the bow down. If you can eventually get it up on plane your RPM should come up to near 7000 but you won't have much power to keep from slowing down when making hard corners.

Section 04-02 of the shop manual (available on this site) provides a pretty good description of how the RAVE valves are supposed to work, but doesn't really describe how the boat responds.

Cavitation in the pump due to a poor shaft seal will result in the boat having trouble getting up on plane also but the engine RPM will be at the 7200 RPM limit. Plenty of fast spinning motor/pump but not enough water flow to make it go fast. (spinning your wheels so to speak)

From your other post, this could be due to partially plugged pump passage. I have gotten into weeds and partially plugged the pump passage. Boat is just overall sluggish and wouldn't get anywhere near plane.

 

[TheYeti]

Last year on my only lake test after purchasing the boat would get up to speed and pretty much do a "wheelie" (for lack of better words on my part) the whole time with my dad sitting up front (he's a little guy). I did not clean the passages that the rave valve goes in to when I cleaned the valves themselves. The springs were there and installed properly when removed and when reinstalled. Thank you again for your replies. Im not experienced with these things but am mechanically inclined enough to do some work on anything. A lot of times I can see the problem but really don't know that is the problem just due to not knowing so any help at all is very much appreciated.
Should I be like scraping the inside of the walls where the valve slides up and down with a screw driver or small scraper or chisel amd letting it fall in there?

 

[wernerml]

If you take just the guillotine in your hand and slide it in and out of its passage in the cylinder wall, it should go in and out with almost no pressure. With the PTO RAVE you may be able to do this with the valve assembled. It is actually a pretty loose fit. If it moves easily that's not the problem.

If it is tight and difficult to move in and out then you will need to clean. Removing the cylinder head would allow you to rotate the crank to put each piston to BDC and insert a rag to catch the crap. Hard to say what that crap in the cylinder might cause. Better safe than sorry.

If the exhaust pressure isn't getting to the rubber bellows it won't move the guillotine no matter how loose it is. That is a small passage and doesn't have much air/exhaust moving through it. Shouldn't get plugged but who knows.

If RPM jumps quickly as you pass ~5500 then RAVES are probably working. If boat still plows, bow high, you are looking at a pump problem.

If it hangs around ~5500 to 6000 as the boat plows through the water the RAVES are likely not working.

 

[TheYeti]

Right on. Thanks again for the info. I'll add this back on to the list. I'm sure there'll be more questions when I get back to it.

 

[TheYeti]

Ok back already so how do i R&R them there heads to properly clean the rave valve passage ways then? Not sure if I'll be able to get out next weekend and will be ordering parts/a tool(I think) for my wear ring so... what do I gota do to properly finish my rave vale job/cleaning?

 

[wernerml]

The passage in the cylinder and the passage in the RAVE body are both straight drilled holes. Get a chunk of wire a bit smaller than the hole and push it through back and forth. Plenty long so you don't lose track of it. A piece of wire floating around in the cylinder is not good. You can also use some carb cleaner with one of those red tubes in the nozzle and spray through the passage. When the spray blasts through easily then its clean enough.

The passage in the cylinder ends up in the exhaust port just down stream from where the guillotine valve is.