had problems with a 250 trailblazer some time ago. wouldnt start seem to have fire and fuel but just wouldnt start. took some advise and rebuilt the top end. piston was wore so went .20 over new rings. still does the same exact thing seems to have everything it needs just wont go. wonder if there could be a timing problem. also looking at replacing crank seals. anybody got anything, really tired of banging my head on the front wheel.

 

Crank seals are what a lot of people over look as you have to have good bottom end compression for it it to run as well as good top end compression. If it's crank seals, usually the one behind the front clutch is the worst one. Just replace the seals and see if it runs ok. Plus don't overlook the obvious if you haven't rebuilt the carb,new air filter,etc. Keep us updated.

 

ok i appreciate the info. is there any timing to do on this engine.

 

Timing is through the stator plate adjustment and the cdi. If the plate hasn't been moved (just for a top end) and the cdi is functioning(sending the small signal to the coil to be amplified) and you have good spark,then it's probably not what's wrong. Things can happen though,if a flywheel key splits allowing the flywheel to move,timing can be altered, a cdi can break down along with a coil and have intermittent or no spark. If seals don't fix the problem,the carb and other mechanical problems have been eliminated,then electrical resistance tests would be next. Just a process of elimination. Take it one step at a time.Keep us updated.

 

well replaced the left side crank seal and put it all back together and away it goes. runs like it did. appreciate the info. now trying to get the throttle to be a little more responsive. seems to be lagging a lot. any suggestions.

 

A new carb kit may work wonders. Plenty of them on Ebay,etc.