96 gsx with low compression

[Tberghold84]

I have a 96 GSX which has me very confused. The carbs were rebuilt and the gray fuel lines were replaced last year. This year the ski will start out of water. In the water the ski is hard starting "most" of the time. Once running it has a bog until about 1/8 throttle, but once past that it is very snappy and fast. My knowledge of these skis is that the ski should barely run let alone be fast and snappy once above the bog with compression that low. Also the other day it would not start at all when trying to load it on the trailer and when I pulled the drain plugs there was a lot of water that came out of the bilge. I have never had that issue in the past. I have not had time yet to investigate where the water came from. I am about to my limits of putting money into this ski, but am also not one to give up. Any help and suggestions would be much appreciated.

 

[Coastiejoe]

What is the compression?


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[Tberghold84]

Sorry I was editing the post and I forgot to renter that part. The compression was 90 psi in both cylinders.

 

[Coastiejoe]

If the compression is accurate, it is done. That said, you said it runs SNAPPY. if it does in fact run well once you get it started and past the "bog" area, then the compression is wrong. Get a different gauge and see what you get.

It sounds like a fuel issue, as in too much fuel kind of thing. Could also be a timing concern. Pull the plugs and see what they look like.


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[Jetskigoodies]

Must be a harbor freight gauge, our harbor freight gauge always reads 90 lol

 

[Tberghold84]

Ha funny you should say that, it is a harbor freight gauge. I pulled the plugs and they are black and wet. I will get another compression tester and retest. I am feeling a little better that 90 probably isn't actual compression as I thought it ran too well for that. I was thinking along the lines of too much fuel until I got that compression reading. When I rebuilt the carbs last year I believe I used the 65 gram needle arm spring because that got the pop off close to where it was before. I don't remember exactly what the pop off was but I believe it was below 30. Should I have used a black 80 gram spring? I think the pop off being too low would cause the symptoms I am having. Am I thinking about this correctly?

 

[- BiRkS_]

If it is indeed a "BOG" that means it is lean. First I would try opening the Low speed screws 1/8 turn then re-adjust your idle. If the problem goes away, it was just that. If it helps a little, then your transition ports are clogged in the carbs (little holes in the throat of the carb. Too low of a pop off will normally cause flooding and "loading up" at idle, and when you crack the throttle it will cough and sputter. sounds to be the exact opposite of your symptoms.

 

[Tberghold84]

Ok I retested compression with a different gauge and came up with 140 psi on both cylinders. I will open the low speed screws 1/8 turn and see if it is in fact lean instead of rich. Although now it appears I have another issue. I located where the water in my bilge came from. There is a pin hole size stream spraying out from the base gasket just under the stern side of the exhaust manifold. If I remove the jugs to replace the base gasket is there any special procedures I need to know? I've pulled cylinders off dirt bikes but never watercraft. Thanx everyone for your help this far.