Broken Rotary Valve?

[John McMillion]

Hey guys, I have just gotten a 92 Sea Doo SP. Compression wise, I have 145 -147lbs. However, I an getting blow by through the carb from the front cylinder. My friend who is pretty familiar with these said that it is my rotary valve. Well we pulled off the intake and low and behold, the rotary gear will not turn when turning over the motor, but you can feel vibration where it is trying to grab. From looking at a description of the part, it must be missing teeth or is broken somehow inside, I have not gone into the motor anymore at this point. My wife and i were considering ordering a rebuilt motor from SBT, but how much would it be just to repair this one. I need an honest answer to see what exactly I am getting into. The rest of the motor and ski are in garage condition. Please advise.

Thanks, John

[Bill O'Neal2]

Re: Broken Rotary Valve?

Typically, a brass gear shears when something gets caught between the RV and the intake port.

You will need to remove the engine and disassemble it. At minimum, you will need a new rotary valve shaft assembly with a new brass gear.

Sometimes, when the brass gear shears off the teeth, like yours did, it moves the steel gear on the crankashft rearward. You may need a crankshaft if that is the case. The rotary valve cavity will be littered with brass shavings.

On an accurate guage, the compression should be over 150 psi in each clyinder. My guess is that your motor may not be in all that good of shape, and replacing it with an SBT motor is a very good idea.

[John McMillion]

Re: Broken Rotary Valve?

Thanks for the info. I'll probably just do that and be done with it, no use in chasing more problems.