New owner of a slt700 with low compression

[tweeaks]

I recently got a 96 slt 700 with compression readings of 30 in front and 120 rear. I am going to pull the head and see what is going on with it, but do not know what exactly I will be looking for. Obvious things like scoring on the walls and cracked piston/rings I get, but is there anything else I should be looking for? Is there anything I should do to it before I pull the head like a leakdown test (which I am unsure of the precedure for)?

I have some automotive mechanical experience, but no 2 stroke/carb experience. So I feel comfortable doing the work myself.

Thanks for the help fellas!

[tweeaks]

[tweeaks]

[tweeaks]

The head o-ring was old and brittle and broke during removal. Is there any chance that's all it was? There is some slight scoring, but I dont have any idea if it would be enough to drop compression to 30 psi.

[casey67]

The first picture at about the 7 o clock position, is that debris or damage ?
Ring end gap looks good- usually the o-ring stays soft-it might be combustion that made it brittle.
I would try an o-ring and check compression again.

sometimes the o-ring could be found on amazon. 3.471 x 3.611 x .07

watercraftsuperstore sells o-ring kits.

[tweeaks]

Here's another pic after cleaning up a little

[tweeaks]

Dang camera flipped on me when snapping that last one. But the left side of the 3rd picture is a close up of the bottom of the 1st picture.

[casey67]

I would try an o-ring, even if it was just out of the other cylinder.

[tweeaks]

Got an oring set for both sides on the way. I dont think the other one will make it when pulled off. I'll update after the new oring is in. Thanks for the help!

[tweeaks]

Well got the new oring in and now I have just more than 0 psi (enough to bleed off the gauge, but not enough to register much). Weird thing is I have 90 on the rear now and I didnt touch that one. Even if it's a faulty gauge there's not enough in the front cylinder to do much more without some work.

If the rear really has 90 psi, and I opt to just rebuild the top end on the front will there be any adverse effects from such a difference in compression?