I have a polaris 300 2x4, i can't seem to get it started. i rebuilt the top end about 5 months ago, it ran for about 2 weeks and died! after i let it sit in the shop untill i had time to look at it. i took the head off found it was all carboned up. after some smooth sanding it was back to the metal. the top of the piston and cylinder wall looked great! it seems to have good compression ( but i need to do a Compression check on it) has good spark! and plenty of fuel in the cylinder. seems to backfire sometimes but just wont start up. i was wonderin is there a way to time these motors? i work on v8s alot and it seems like its outa time? could this be? never really worked on a quad befor. any info would be great!


thanks
Beep Beep

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94 polaris 2x4
93 duster 2.5v6
77 roadrunner 318cid

 

HMMM a 300 2x4? Sounds like ELORY2,s department. He has a modded 300 express. I would start with compression. Anything under 80psi will not run. A good compression should be between 120-135 psi.

 

wow i didn't think they needed that much compression, i will get that check done! if it doesn't have that much compression, could it be my rings that i put in?


94 polaris 2x4
93 duster 2.5v6
77 roadrunner 318cid

 

When did you put the rings in? Did you have the rings lined up right? Yes it does need that much to run properly. Did you inspect the piston and did you get the right size rings.

 

i'm almost sure i lined the rings up right :S , the shop that bored the head told me the sizes to buy for the cylinder. i bought the piston rings and pin all from polaris! i might take the cylinder off and check the rings. i'm guessin that what it is cuz i'm almost for sure it doesn't have 120psi of compression
if the rings r not lined up prop. would this cause lost compression ?
thanks for the info and plz keep it coming i need all the help i can get [img]i/expressions/face-icon-small-tongue.gif[/img]

beep beep
brad

 

It will run with around 90 to 100 but not too good and will be hard to start.Try squirting a small amount of oil in the cylinder and see if that helps.

 

right after the rebuild i was told to add a lil bit of oil like u said! but i got a lil carryed away with it and added a huge amount + then carbon build up which i have already takin off the head [img]i/expressions/face-icon-small-smile.gif[/img] i was being very stupid and added more then what i thought would help. i think i mighta did some damage with doin this? would this cause damage or just carbon build up? when i took the head off there was alot of carbon which i think came from burning all that oil i added [img]i/expressions/face-icon-small-sad.gif[/img], well after i cleaned the carbon out i again added a very very tiny amount of oil( the compression would not blow my finger off the spark plug hole) with that oil added it will now! which i'm guessin brought some of my compression back. would addin that much oil to the motor damage it or just carbon it all up ? (when i added all the oil the first time i was 14) now i am 16 and rebuildin a 1977 roadrunner and have tore down alot of v8s! so i have a better clue of whats goin on now but quads r nothing like a big ole v8 [img]i/expressions/face-icon-small-tongue.gif[/img] just some more ?'s to have answered my knowledge i have the better off i am. keep it coming guys!


beep beep
brad

 

GEt you a compression gauge and check comp. and get back with us.

 

Adding to much oil really wont hurt anything. There are pins on the piston to line up the rings. If the rings are not lined up right they can break very easily and this will cause a loss of compression. You need to take an accurate compression test and then go from there. We will help out best as we can without actually being there to check it out.

 

Spark, compression and fuel. You said you seen it has good spark and cylinder was wet with fuel. Now you need to see a compression number.
These motors don't usually just go out of time. If they ever do, it usually means big problems and you most likely woulnd't have spark at all. The flywheel is held by a key which is possible to break. I have just never seen it happen but I may have heard it once or twice. My point, I don't believe it is your timing.
Check the compression or atleast take the jug off to ckeck the piston and rings.