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Jeff Policky
Jeff Policky, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 2425
Experience:  Yamaha Gold, Suzuki Gold, Honda Bronze, Polaris Bronze, BRP
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97 Yamaha ventura jet ski rev's good out of water, but will

Customer Question

97 Yamaha ventura jet ski rev's good out of water, but will not rev in water, Any ideas Mike
Submitted: 2 years ago.
Category: Motorcycle
Expert:  RSRBOB replied 2 years ago.
Hi Mike, thank you for your inquiry.There are a couple of things that can cause the symptoms you are experiencing.The first thing would be a mechanical problem in the engine. The reason this is a possibility is that when the engine is mechanically compromised, it does not make as much horsepower as it should and therefore cannot rev up properly. To determine the soundness of the engine mechanically, we need to do a compression test on all 3 cylinders. If there is a problem in there, this will show it.A couple of fine points on doing a compression test. First, leave the other 2 spark plugs installed while doing the test on each cylinder. The engine actually cranks over faster with the plugs in and not out. The next thing is make sure you hold the throttle wide open and ground all 3 spark plug leads to the cylinder head by installing old spark plugs in the boots and laying them on the head. This prevents any damage to the CDI box which could be caused by charging the capacitor inside it without giving it a release path to ground. You don't want to leave the caps on the plugs in the cylinders, the ski might start.Let me know what you get and we can take it from there.THanksRSRBOB