polaris trail blazer 250 wont start HELP!!!!!!!!!!!!!!!!!!!!!!!!!

hi i have a trail blazer 250 1993 and it wont start
if you leave it for a while an try to start it will try to fire on the first pull but then nothink and the only way ive managed to get it started is to use an air line to blow throught the carb and it will usally start and will be fine when its running but just wont start any other way its got a good spark and all jets in the carb seem clear and fuel is coming through also when ive pull startin it for a while the plug still seems dry has anyone got any ideas of what it could be  

have you checked the compression?

compression could be a little down on it which makes it backflow through the carb, keeping it from drawing in fuel.
using and airline would help push fuel into the cylinder.

compression should be between 115 psi and 120  
Keep it RUBBER SIDE DOWN!!

hi thanks very much for your help will check compression tomorrow  

hi just done a compression test and its only 70psi what would you say is causing it? (rings?)  

Installing piston rings is only a temporary repair at this point. If you are down to 70PSI than your cylinder is tapered and wore out. You need to measure the cylinder and determine what oversize piston will work and have the cylinder bored over as this is the only lasting repair. I always replace the wrist pin and the upper rod bearing when I do a top end on any polaris 250 engine. I hope this helps.  

Also, if you do rebuild the top end, although the unit is oil injected, it is a good practice to premix the first full tank of fuel to about 50:1 to help with seating the new rings.  

yes 70 psi is way too low for a 250cc 2 stroke engine, take the cylinder and have it checked to see if it needs to bored or if honing will straighten it out. if  it has to be bored then get the proper oversize bore piston and ring kit. (it will come with a new wrist pin and wrist pin bearing for the piston)

if the cylinder just needs a good hone then have them hone it and buy the stock rings for it. could just be broken rings, or as well the rings can wear down low enough for the cylinder to lose that much compression. sometimes a good hone job and new rings can bring it back to life. you wont know until you get it to the machine shop.

i would block off the premixer pump altogher and mix my fuel and oil in the tank at 32:1

you never know with the premixer pumps if the lines are clogged or the pump gear is broken.

if you mix it in the tank then you don't have to worry about it.
and you'll have less opportunity for the rings to burn up because the pump went out.  
Keep it RUBBER SIDE DOWN!!