Compression question

[TravG]

I've a 1995 Kawasaki Zxi 750 that's been driving me nuts. The engine was overhauled, the carb completely gone through, and general touch-up here and there. The work was partially done by me and partially by the previous owner. The problem is that it won't start. I've checked the fuel system inside and out and while I can't be certain it's not the problem, nothing obvious jumps out at me.

I checked the compression and it's reading 125 psi on both cylinders. The owners manual says 185 psi and the service manual says 125-193 psi. I'm guessing since I can't start it, the low compression would be normal? Does the compression then increase once there is cooling water in the exhaust?

I need to figure out where my problem lies and I don't know if I should continue to troubleshoot the fuel system (which is where I suspect the problem lies) or with the engine itself. I've decent spark and if I pour a few drops of fuel down the carb throat it starts for a second.

 

[bigdaddypt]

Re: Compression question

Your compression reading is fine for that ski. It sounds like either your fuel pump isn't working and/or there is a leak somewhere in the fuel system causing air to get sucked in and not the fuel from the tank. You can do a test for holding pressure in the fuel system. I can't remember, but I think if it can hold 15psi for 15 minutes then it's sealed properly. If not then you have a leak somewhere and have to find and fix it.

 

[DoGood]

Re: Compression question

these engines need 3 things to run, compression, fuel, spark. one of them is not working for you.
your compression is fine if both cylinders are at 125 psi, you'll probably get better compression when the engine is warm, or your guage may not be accurate.

in order to check the spark, get a spark tester or do it the old way, by holding the plug grounded to the engine.

I'm guessing you have a gas problem though, because if the fuel was working and the spark wasn't you'd smell the gas.

my first guess would be bad fuel pumps. they are attached to the carb itself. whomever went through the carbs most likely did a poor job and it needs to be done again.

also be sure that the fuel lines are run correctly and that the fuel switch is turned to on or reserve.