Just wonderin what the compression should be in my 2000 trailblazer 250 and do u check it by just pulling the machine over but not running it? Any and all info would be great thanks in advance

 

compression should be at least100 psi or more. you check itwhile the engine is cold and @full throttle. im guesing to hold the starter button in at least 5 to 10 seconds for a true reading.

 

So fire it up while its cold and hold it wide open? how long do u hold it wide open til the needle on the tester stops moving i'm guessin? thanks for the quick reply

 

Take out the spark plug, screw in the tester,leave the engine run switch off(you don't need spark), hold the throttle open so air gets in easy, turn the engine over for about 5 seconds and........that's it.

 

yes dont start it. with a cold engine w/ the tester in the spark plug hole will give the truest reading.

 

awesome thanks alot for the quick replies..its a 2000 and its never had a rebuild so i'm guessin it might be time soon..if it is what should i do? bore it out and gou up a size or just get a wiseco stock? currently i have a K&N filter 23" mudlites Aaen green primary and torquer pipe and silencer

 

just do a good compression test first and see what you have. if its near 100 then i wouldnt. as far boring it out you would have to messure the cyclinder to see if it really needs it or just a hone job and new rings.