Rave Valve Problem

[etemplet]

Ski I"m restoring went out for a water test today. It had a little flat spot at 5k RPM but... topped out at 6900rpm and 51mph on the GPS. I thought the Raves might be gunked up or something. Ski has great compression and good power. I guess the moral of the story is... we worry about .005" here or there. I know the previous owner didn't have a clue about any performance issues. Question.... I'm not opening the engine and am planning on taking measurements for the correct clearance. Is there a preferred method other than... "You'll shoot your eye out kid?? " I can get a length on the valve and a depth on the valve mounting face to piston contact. That will work. Touchdowns everyone !!

 

[GGuillot]

Where did the broken pieces go? I'd look for an overbore indication on top the pistons, but you said that's not an option to open the engine up. Good luck with the measurement method trying to figure out the clearance.

 

[racerxxx]

The manual will give you the clearance IIRC. This is why seadoo only sells a first over piston. It takes you to the minimal allowable clearance. I posted the numbers here somewhere years ago I think?? But if you can see the top of the piston and read the size you can determine how much you need to shave the valve. I've never done it. I stop at first overs. I just had a pair of cylinders that I think the local shop messed up on my first overs so I bought another pair of standard bores and another pair of seadoo first overs and sent those to Group K and have them bore them.

 

[etemplet]

I've done a number of cylinders and raves fitting them to the proper piston clearance for the raves. It is pretty straight forward and easy when you are building the engine. What I am planning is to fit the rave with the engine assembled and not knowing the bore size. which will be a bit of an adventure. If I can find a couple of slotted raves in my parts pile I'll probably do this Monday.

 

[etemplet]

An interesting point in this finding is that the raves were functioning even with huge chunks missing. I was able to get top speed.

 

[etemplet]

I found some raves in my parts stash... that is an adventure in itself. I had the marked standard bore. Lord if those were in a cylinder with a standard bore... yikes again. Bellows did not even have a spring on the bottom.... par for the course with some of these owner/so called mechanics. I'm gonna do a water test later in the week. Gonna be interesting.

 

[etemplet]

I'll likely have an interesting report on the next ride of this ski. What an adventure !! Data gathering is most excellent though for future troubleshooting. The fact that the raves pictured were working provides valuable information about clearance requirements.

 

[racerxxx]

787 has no spring in the bottom of the raves.

 

[etemplet]

Kinda didn't word it correctly. Neither bellows had the bottom spring retainer to hold the bellows in place. Sorry.

 

[racerxxx]

Correct, 787's don't get a lower spring on the small end of the bellows. You can get one from a 951, but they don't come with them. Mind you, later RFI stuff might, but I only look at 95-99 787 carbed ski microfiche

 

[etemplet]

This is the first one I've seen with no bottom spring retainer. Just a hobby for me but I've done a few. I won't put the bellows back on without a spring. I have used an o-ring once or twice. I like em' tight.