DT40: Rebuild or not

[don diego]

My 1986 Suzuki DT40 lost compression on top cylinder. Is it possible to diagnose condition without tearing into the motor? This motor has been a faithful and dependable friend for 12 years. But I know a rebuild can get more pricey than another motor. Any suggestions are appreciated.

 

[MARV1]

Re: DT40: Rebuild or not

Sell it as parts, buy a newer 4-Stroke, even used ones run great and longer...

 

[deejaycee_2000]

Re: DT40: Rebuild or not

unfortunately you have to open it up to see the damage ....

 

[don diego]

Re: DT40: Rebuild or not

Today I rechecked compression on this motor. Still 140 on bottom, 0 on top. I then added 80/90 gear oil to top cylinder and rechecked compression. Top came up to 30. I did this twice. Same results. Then I noticed oil was draining from pee hole. Could this indicate blown head gasket allowing the oil from the cylinder to leak into cooling system?

 

[deejaycee_2000]

Re: DT40: Rebuild or not

You might have a hole in the block, regardless, it would need to be opened up to evaluate the damage ...