zero compression on mag side 1998 gsx ltd

[wmenzie2001]

Hi Guys
I have a 1998 gsx ltd, I bought it used last year and the previous owner just did a top end rebuild. I went out on the water last weekend and it just started to bog down. I put it on the trailer got it started(by pressing the throttle quite a bit) hooked a hose up to it and it idle fine for about 20 mins. I then proceeded to put it back on the water again and within 5 mins it bogged down again. I brougt it home and did a compression test "0" on the mag side and 90 on the pto side. Now my question is could this just be a dirty carb problem? Or does it need another new top end? Rebuilding the top end is my last option I want to make sure I explore every avenue first.
Thanks

 

[El Toro 33809]

Welcome to the forum. With compression like that, there is definitely some top end damage. When was it rebuilt? Why did it need to be rebuilt back then? It sounds as if whatever the problem was hasn't been corrected so it went through another top end. Had you done a compression test prior to purchasing it? If so, what was the compression then?

 

[LouDoo]

By running too lean a carb. problem could have caused this, but Tim is absolutely correct, you've got damage to the top end. Go ahead and pop the head off and see what's going on.

Lou

 

[wmenzie2001]

Welcome to the forum. With compression like that, there is definitely some top end damage. When was it rebuilt? Why did it need to be rebuilt back then? It sounds as if whatever the problem was hasn't been corrected so it went through another top end. Had you done a compression test prior to purchasing it? If so, what was the compression then?

Unfortunately I was a noob when I purchased the machine, and never did a compression test. I ran it all of last year with pretty much no problems at all. Ran it most of the year this year and again no problems. I can get the machine started but it needs me to hold the choke open and the throttle down and it will start but dies as soon as I let go of the gas. This is why I was thinking it was a carb problem.

 

[El Toro 33809]

A carb problem may have lead to damaged cylinders, then to zero compression, but now that the damage is done, the cylinder/piston will need to be repaired along with whatever led to the failure.