Really low compression

[dust1014]

I have a 99 blaster, i bought it awhile back from a guy who bored it out 20 over. Recently it has had almost no compression at all, i fear i need to rebuild it. I am new with 2 strokes, i have never had one before but i know my way around engines. What i really need to know is if its possible to just replace the piston rings and head gasket? or do i need to bore it out again and buy a top end rebuild kit. The compression is so low it won't start, you can easily push don't on the kickstart with your hand multiple times.

 

[Awk08]

the piston is your biggest cost of a rebuild, it'll come with rings
should be only another $60 max for a bore to fit the new size piston.
no sense to risk just piston/rings, only to have the same, or worse, results.
do it rght the first time

 

[dirtysquared]

I'm with Awk that. Better to start fresh and know what you have. No nasty surprises that way.

 

[dust1014]

so just bore it out again and get a new piston and rings? what would be the best size to go up to? right now its at 66.50mm i believe

 

[blasterdemon7]

Good advice from Awk. Do not cheap out on it ! A piston with to much clearance will break a skirt off and take the engine case and maybe the crank to.

 

[dirtysquared]

A good shop will measure it, and bore it to the next oversize and match it to the new piston. Thats the easiest way of doing things. Get only OEM or cometic gaskets also. No paper junk.

 

[dust1014]

alright thanks! I had no idea what to do, huge help.

 

[Blaaster]

With such a low compression I would fear that the piston and rings may have been damaged by a lean mixture.

Before you remove the head and jug perform a leak test to see if the engine is air tight.

 

[tfaith08]

While you have it apart, go ahead and replace the seals. That only adds about another hour of work and about $40 if you buy them direct OEM.

Also, let the shop doing the bore job worry about the needs of the cylinder. Ask them what it needs and order that piston. When they get the piston, they can get the clearance right.