1998 Yz 250 No Compression Won't Start???

Question

I have a 1998 Yz 250 was riding in field when it started smoking, and we thought there was a hole in the radiator, so we put radiator stop leak in there about a week later and tried to crank it, but no compression, and tried to jump it, but wont crank??? Help!!!

Answer 1

it started smoking or steaming?  what area did this appear to be coming from?

hole in radiator should not cause no compression unless the lack of coolant in the radiator caused the engine to over heat and burned up the top end or a hole in the piston.

sounds like you have some mechanical trouble shooting to do and potentially replacing the top end (piston, ring).

edit:  another good thought  guardrailjim! could be a head gasket.  simpliest thing to do is run a compression check on the cylinder and on the cooling system.  I would also advise not running for extended periods with the radiator stopleak, flush and get radiator repaired if there actually was a leak / hole.

still doesn't explain why one would think there is a hole in the radiator...

Answer 2

sounds like you broke a ring on your piston. you need to do a top end job on your motor.

Answer 3

You may have just a leaking head gasket.

Coolant would get into the combustion chamber and burn with the fuel - your exhaust would look like a crop duster.

When kick starting or checking for compression - the pressure would blow into the cooling system, making it feel like there's no compression.

Pressure test the cooling system to check for a head gasket leak.

Answer 4

pull the spark plug and inspect.  if the head gasket is blown, then it was left sitting for a while, potentially some water got into the cylinder and it might show on the plug tip after you tried kicking it.

likewise, you stated it was smoking heavily, the plug might be fouled too causing it not to start.

compression check the cylinder and that might tell a lot.  and get the rad stop leak out as soon as you can.  that stuff is designed to be temporary solution not long term.

Answer 5

as stated above, needs a new top end, also clean out the radiator of all stopleak

Answer 6

Needs a new top end.