finn
24.04.2021 12:23:15
How many hours are on the crank? If it is 300 ish, then a full rebuild or re-engine. If 150 ish, then a top end would likely be fine.
See full version: One cylinder with 0 compression
How many hours are on the crank? If it is 300 ish, then a full rebuild or re-engine. If 150 ish, then a top end would likely be fine.
So.. This started because the jet ski was bogging down in water and would not go higher than 3k RPM. I replaced all below:
Gray fuel lines
Fuel filter
Fuel selector
Cleaned out carbs
Still bogging down. I checked the RAVE Valves I noticed the one valve that was stuck which now explains why piston was shot.I pulled it out and and replaced the entire RAVE Valve. Still didn't work. I decided to did the compression test and here is where we are now. [links]
I would try to determine WHY you had the failure. If you don't solve that, you'll be fixing your new repair. here
Most two-cylinder engines should have about 140psi, but not all. Most three-cylinder engines use a lower compression usually around 110psi. The difference in compression between cylinders is important as well. The standard is 10% difference for all but Sea-Doo, which has a 5% tolerance. If you have a Yamaha with 130psi and 140psi, as long as both compressions are with-in spec, the compression is good. If you have 130psi and 150psi even if both compressions are with-in spec, compression is bad because you have more than a 10% difference between cylinders. more
Install the compression gauge into any spark plug hole. Open the throttle fully. Press the start button and rotate the engine for 5 to 7 seconds. Read the compression gauge. Refer to the shop manual to determine if your compression is good or not. There is not one compression for all engines. You should perform this procedure at least twice per cylinder. more
THE TEST - 1) Make sure both spark plug caps have spark plugs mounted in them, and those plugs are grounded to the cylinder or head. 2) Hold the throttle wide open to admit the maximum amount of air. 3) Hold the start button down until the needle on the compression gauge is no longer rising. 4) Test both cylinders.
GETTING AN ACCURATE (as possible) INDICATED COMPRESSION READING here
I am looking at picking up a '97 GSI that has low compression in one cylinder. The guy said that it was running fine all summer last year and then it started running bad and now has low compression in one hole.
Is there any way to tell what it will need (top end vs. entire motor) by looking at it in his driveway? Or do I have to tear the thing apart? [links]
Four weeks ago last time I was working on it, front side was 130 and back side was 85, two month ago it was fine but was having trouble getting fuel to pump into pistons so sprayed some carb fluid in that back piston then turned it over and heard a pop, reason why I thought it was a gasket but the gasket looked fine.
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A 2004 Polaris Viarge with a low compression reading in one cylinder will misfire and cause the watercraft to run rough, low compression in all cylinders will cause the engine not to start.
Performing a cylinder compression test will indicate the engine’s overall condition provided a high quality compression gauge is used for testing and the battery is fully charged. [links]
2004 Polaris Virage low compression refers to when cylinder compression falls below 100 psi per cylinder. A cylinder will typically fail to fire when compression falls below 90 pounds.
The following repair information identifies possible causes of low compression. Check for one or more possible malfunctions: [links]