I just bought a xplorer 300 from a guy who said his kid was riding heard a grinding then he either shut it down or it died and now won't start I've got 105 pounds of compression new spark plug with blue spark and cleaned carb but still will not fire unless I spray just a touch of starting fluid. I drained the tank and put fresh 40:1 fuel in the tank still cannot figure this quad out any help would be much appreciated

 

Probably the piston seized when the kid was riding it. 105 psi is at the lower end as far as compression. If it won't kick off on starting fluid I'd pull the top end down and also check the rod for any up and down play to make sure it's ok also.

 

It'll start up on starting fluid but will not stay running

 

Either is so much lighter than gas and can get one to run as long as the either holds out. My bet is still the top end needs to be pulled down with this low amount of compression showing and wouldn't hurt to change out the crank seal behind the drive clutch. This is another area also that gives people fits if it leaks.

 

ok I pulled the top end off and found the front bottom piston skirting was broke off and gone I found the remnants of it in the exhaust pipe on front of engine. I measured the piston without rings in the cylinder wall if I'm measuring right it looks like .005 without the rings with the rings it looks like .002 the cylinder wall feels and looks smooth with no grooves. Would and piston and ring kit do the trick or should it be bored out with a .20 over kit installed?

 

Always bore to the next over size. Cylinders are hardly the same measurement top to bottom and usually a waste of money of you put a stock piston back in.Be sure to check the rod for any up and down play,plus I'd flush the bottom end with kerosene,naptha,etc to remove any metal shavings.

 

Ok I'll get things lined up thanks for all the advice!