787cc melting rave pistions

[Pistol_pete487]

Hello hoping some body with more knowledge then me which isn't alot with seadoo can help me diagnose my 1996 changeller I've put 3 r.a.v.e kits on it the past 2 years and after a few hours they melt I have 150psi in both cylinders. I just took the cylinder head off and noticed alot of carbon build up on both pistons.I've read on other post that lack of rave vavle maitance can cause excessive wear in the guillotine solt causing more heat then normal. I'm the 3rd owner of the boat the owner before me rebuilt the engine and due to bad decisions on my end I went in too shallow water the second day of ownership and sucked up a rock and snapped the drive shaft. I have sense fixed that problem last summer replaced the jet pump again due to taking it to a shoty mechanic who broke my fins in the pump not thinking to look inside it I assumed it was a power vavle problem which was causing it to not plain out also the top red screw was melting on the pto side so I had them both replaced. But every few hours of use they go bad im wonder if I should order new jugs pto and mag. I'm also in the process of going threw carb and changing out grey fuel lines thanks.

 

[Pistol_pete487]

 

[Poormanracing]

Check your oil injection system to much oil will cause them to melt.check to make sure the gasket is on the right way.and make sure to use a new orange on the rave shaft.also makes use the red caps are even on both cyl

 

[Poormanracing]

View attachment 57941

Those rave valve base looks like they are from a rfi sea doo and they are a little different

 

[L. Dean Ficarro]

Those rave valve base looks like they are from a rfi sea doo and they are a little different

Definitely looks like you have the incorrect rave assembly, maybe try looking up the part numbers and searching them up that way. There are free pdf files for manuals online if needed! Good eye, Poorman!

Tell us what you find out, as well.

Cheers

 

[POPPS]

You are melting the rav cap because of inadequate cooling,,,if you were racing and blessed like Pops Fischer ,(fastest recorded 800). BRP would supply you with metal caps,,,that can’t melt,,trust me,,,loose or tight rav clearances DO NOT cause them to melt,,,but an overheated engine will…I have 2 in the shop right now,,,determine why it is not cooling properly,,,and sometimes easily overlooked,,,is the pump not producing proper water pressure to circulate the water,,,also check that the cylinder drain lines are totally clear,..

 

[mikidymac]

I have seen the cap threads melt out from the shaft o-ring being old and hard as the hot exhaust gasses travel up the shaft and get it hot enough to melt the plastic cap threads. I have also seen engines starved from water get hot enough to turn the exhaust manifold paint brown and not melt the rave caps so who knows. From my experience an overheated engine will seize before the rave caps melt but I have not been in the racing world like POPPs has so I am sure he has seen more carnage.

 

[trains39]

I recently purchase a used 97 GTX. The individual who owned it was not mechanically inclined. He did replace the Rave Valves. How would I identify the correct Rave valve?