New Rave Valve Broken

[mully]

So I replaced a rave valve that broke at the shaft with a new sbt rave valve. Now about 3 weeks later this happens. The broken part slid into the cylinder after the engine was turned off. So upon trying to restart the thing wedged the piston to a halt. What would cause this and does SBT warranty rave valves?

See photo.
Thanks mully

[Technical Support]

Re: New Rave Valve Broken

Yes all our parts have a 90 day warranty against defects. Either fillout the online warranty claim form of call in M-F 8-5est. http://www.sbtontheweb.com/owarranty.htm

[Technical Support]

Re: New Rave Valve Broken

I'll note that I have never seen one break like that - ours, or OEM. But a clean sharp break, especially at a location like that, is usually a casting flaw.

[mully]

Re: New Rave Valve Broken

I'm just very glad that it slipped into the cylinder after the engine had been turned off. I have a small impession on the piston but from what I can see it should be fine until fall. I can see a shinny spot on the top ring but it's not bent up.

[1fastski.com]

Re: New Rave Valve Broken

that scoring does not look very good , if not water injestion then jetting needs to be looked at .

[mully]

Re: New Rave Valve Broken

I think that scoring is from the first rave which the stem broke then allowed the rave to drop. The rave melted as the engine ran along. I finally fixed it with this new rave and then the thing cracked and droped into the cylinder jamming the piston. I put the head back on and pluged the old rave valve in (temporarly) and it ran just fine on a hose. I'll have to get some new head gaskets and a new rave but it runs like this for now... I suppose I will have rebulid the top end again this fall but for now ride it till it you break it. O I also find that my oil pump was way out of alingnment(lean) so I fixed that too.

[Bill O'Neal2]

Re: New Rave Valve Broken

What size pistons are in this motor? Std, 1st over, 2nd over, 3rd over, 4th over ?

The "scoring" Chris was referring to is the scoring on the clyinder wall above and around the exhaust port in the first picture. Those are siezure marks made by a partially siezed overheated piston.

[mully]

Re: New Rave Valve Broken

I don't know for sure they came as an SBT Cylinder exchange/top end kit. I have had a siezure due to my oil pump alingment. I just found and fixed that today. I was even premixing 100 to 1 because I didn't know why it was siezing. I think I siezed up 2 or 3 times. I didn't premix today and it ran good all day. Has a funny power curve because of the missing rave valve but It's for fun not sport so I don't care. Once I get the new valve in should be good to go till fall. Why is piston size important for you too know?

[1fastski.com]

Re: New Rave Valve Broken

if the piston is bigger then 1st over the rave clearnce will be tight 2nd over you must cut the raves or they will hit the piston .

[mully]

Re: New Rave Valve Broken

So SBT is sending me a new rave valve thank you. I am wondering now if the ski is running ok and I am happy sould I just continue to drive it. Does anyone think that I need to rebuild due to the cylinder damage seen in the photos. I found out that I do have the 1st oversive pistons cylinders.

[chris w]

Re: New Rave Valve Broken

I would check rave valve clearance like fastski recomended. Somthing seems amis. 2 rave valve failures in the same hole, how common is that?

I cant tell if it is the pic or not, but is looks like there is some aluminium trash on top of the piston.

Yes, the piston and cylinder have been too intimate, may even be possible that the rave was kissing the ring and causing it to scuff the cylinder and create extra heat.

To keep running may cause a big seizure that could lead to a rod hanging out. You be the judge.

[1fastski.com]

Re: New Rave Valve Broken

the pistons will look worse then the cly , but if your compression is good run it for the season and fix it over the winter . knowing you had a oil pump fail you will want to inspect the crank , the good thing about running extra oil is in most cases you save the carnk as its tuffer then the pistions :-)

[chris w]

Re: New Rave Valve Broken

Also looking at the pic of the rave valve, the way it is flared out like that, I bet it takes a bigger smack than the starter could provide to get it to do that. That looks like it made contact with it while it was running, not just starting.

[Bill O'Neal2]

Re: New Rave Valve Broken

Using a round file, file off about .010 to .020 off the sharp edge of the rave valve and it will quit hitting the piston.

When a rave valve hits a piston, as the piston passes the rave valve, the rave valve will damage the rings and the ring lands on the piston.

That is probably not what is causing your siezures though. That is a different issue.

[mully]

Re: New Rave Valve Broken

Well I was told that the engine ran fine until it was shut down. I was not the rider so I don't know 4 sure. I will file the new rave and the mag side one too. Thanks for the tip. It would be best if I could get through the summer with this engine. Just got my tax bill.

How hard is it to just replace a cylinder sleeve instead of the entire cylinder? Seems like that might be cheaper. My buddy has access to a hyd. press. I just have never done it before.

Thanks