03 trailblazer starting problems

[andersonatvrepair]

Hello I'm new here and I've been searching the web all day for answers and found nothing.
I'm working on a "03 Polaris Trailblazer 400" the reason for the quotation marks is that's what i figured out by the VIN and pic on Internet.
Problem i am having it will turn over all day long but never starts.
compression is running 80-85 psi
good spark @ plug and good fuel @ carb
this puzzle me a little
there is 2 cycle oil in the oil tank
and also premixed into gas ( was brought to me like this)
blows from exhaust and back of carb where the air filter goes. acts like it jumped time but everything I've read i don't think this thing has a "timing chain"
could i be looking at replacing the piston and rings?
any suggestions and help is appreciated in advance thanks

[Bait]

yeah the problem is the rings are worn or a bad piston. The compresson is too weak and the blow back is due to the ring failure. Put a new top end kit in it and it will be fine. Also dont run both premix and oil in the tank it needs to be one or the other.

[andersonatvrepair]

Thanks Bait what is the normal psi to run manual says 115 ppl on here say 90+

[Bait]

Originally Posted by andersonatvrepair

Thanks Bait what is the normal psi to run manual says 115 ppl on here say 90+

mine had 90 cold and 80 warm and i was getting the blow back through the carb and it wouldnt start when warm. My piston was fine and i just replaced the rings and now im at 130. So you can see what 10lbs will do these bikes. The way the engine is design any leakage and your screwed.

[andersonatvrepair]

just took jug off and appears like it been resleeved* unless these engines have steel "sleeves" in them already.Also has gas in bottom of motor. I posted pic under my photo alubum. couldn't figure how to insert them into message

[Bait]

Originally Posted by andersonatvrepair

just took jug off and appears like it been resleeved* unless these engines have steel "sleeves" in them already. I posted pic under my photo alubum. couldn't figure how to insert them into message

i cant see a sleeve in the picture but then again im on my phone. Is the piston standard size>? it should have marking on it.

[andersonatvrepair]

markings on piston is 0.25 50-30004p i was just tryin to look it up and nada

[Bait]

Originally Posted by andersonatvrepair

markings on piston is 0.25 50-30004p i was just tryin to look it up and nada

well thats a oversized piston for sure

[andersonatvrepair]

i thought so also just by the # i was figuring by atleast by .25mm

[andersonatvrepair]

so this is what i'm figuring new jug piston & rings should fix this