1990 SUZUKI DT 150

[DAVID E. SPIVEY]

I RECENTLY REPLACED THE WATER PUMP AND NOW HAVE LOW COMPRESSION ON ALL 6 CYLINDERS. I BELIEVE THE CRANKCASE SEAL MAY BE SUSPECTED??? I PULLED THE RIGHT CYLINDER HEAD OFF AND FOUND NO EVIDENCE OF SCORING OR WATER. CYLIDER WALLS WERE SMOOTH. WHAT GIVES??? THIS MOTOR ALWAYS HAD A ROUGH IDLE BUT RAN WELL ABOVE IDLE SPEEDS. THANKS FOR ANY INFO!!<br /> SPIDAWG

 

[jim dozier]

Re: 1990 SUZUKI DT 150

DON'T YELL (CAPS)! Perhaps you just need to decarbon the engine. Put the heads back on with new gaskets, torque to specs and run a couple of cans of decarb through the carb throats. (Do a search on decarb if you are unfamiliar with the process). If what you say is true about the cylinder walls your rings are probably OK. I would suspect improper compression readings as a possibility also. Engine should be warmed up, all plugs out, full throttle, with a screw in type gauge. What were your compression numbers anyway?<br /><br />Also, a bad crankcase seal will not affect static compression readings in the cylinder head although it will affect pressure in the crankcase and the way the engine runs.