HI, i have a 2001 trailblazer 250, bought it for the kids to play on. I just had the top end rebuilt at the dealer(the guy I got it from paid for it ) it only had 30lbs of compression, got it back and its only a 90 now and i know it should be at least 120 ..so heres the prob, i ran it for about two hours and it left me stranded, AGAIN, pulled the plug and its a gray color not brown at all so im disconnecting the oil injection. Ive pluged the line into the carb, plugged the tank, disconnected the throttle cable from the injector, do i actually have to buy a block off kit or can i mix and go??? Any advise is appreciated ...

 

Welcome to the forum! Best to ask any future questions in the Polaris section. First thing I would do is pull the cylinder and have it checked out! If too much clearance was allowed you could seize up another piston! Oil pumps are pretty reliable,but a lot of people blame them when things happen! Also is there any up and down movement on the rod or any bearing noise when you had the cylinder bored the first time or did you check this? A bad rod bearing or crank bearings can take out a new top end! Have seen this happen many times when these are not checked out! Plus the MAX clearance on the bore should be .002 clearance measured at the bottom of the piston and bottom of the cylinder! Just pull the small hose from the cylinder to goes to the oil pump and see if it's wet,if so the oil pump is working,plus always bleed the pump(has a 10 mm bleed bolt on top of pump to remove any air) Especially with an 11 year old machine, its probably time to rebuild the bottom end also if it hasn't been done recently!Plus the first tank of gas needs to be premixed at 50-1 ration for break in. OPT

 

Thx OPT, ive been on this site alot the past week and saw alot of ur threads, ur the best and i was hoping to get a reply from u personally...dont know aboit any of the enternals on this quad at all, my quad is a zuki, lt250r...EZ to work on and this polaris seems to be a real pain it the butt. Im gona give it a tank of gas and let the rings seat in and check the compression again, the dealer SWORE he put in a wisco piston but when the tech gave me the box back its some brand called NAMURA, which all im seeing is complaints about em, and ideas how to tell what there w/o a teardown?

 

If you are showing 90 psi best to tear it down any way no matter what piston is in it and check out the bottom end(any crank bearing noise as you roll the rod around and up and down rod play,there should be NO up and down play,side to side play is ok) along with the cylinder clearance that they bored! If the cylinder and piston are not seized up,just pull the piston,remove the rings,place piston in bottom of cylinder,then using a feeler gauge measure how much clearance you can slide a feeler gauge in between bottom of piston and bottom of cylinder. A piston is considered worn out at .005 and will break the skirt off a lot of times when it goes past .005 which will a lot of times damage the bottom end bearings.. A lot of shops allow too much clearance to begin with! OPT

 

Fml, welp sounds like im im for a tear down, i guess if ya want something done right...do it yourself, or take it to OPT.