Hi everybody I'm new to the Forum I just purchased at 86 Polaris Trail Boss 250 for $370 the problem I am having is the bike will only start when I spray carb cleaner in it I took the carburetor apart cleaned it up I noticed when I take the airbox off and put my finger in the carburetor and pump it by hand there's no fuel coming out I left the throttle open just to see if it would flood out and nothing I checked all the Jets to make sure everything was cleaned I sprayed the holes with carb cleaner I only have a fuel line going to the tank to the carburetor I don't know if I'm missing anything since I bought the bike used I am getting good spark I don't have a battery so I just been using the pull start so if anybody can help I appreciate it and have a nice Thanksgiving

 

If you're sure the carb jets are clean and open,all passage ways are blown out,fuel is getting to it,good spark,but won't run,open the throttle wide open,shoot a short burst of starting fluid in the back of the carb. Let off the throttle and see if it cranks and runs. If it just pops back or only runs until the staring fluid is gone, check the compression next. Compression needs to be over 100 psi for one to run right.

 

Okay I will give that a try I know when I spray carburetor cleaner in the back it fires right up but but then shuts right down but this time I'm going to drop the throttle to see if it runs I pump the throttle a lot of times just to see if it floods the carburetor with gas and I get nothing I only get a little bit of wetness thanks for your reply so fast

 

I'd ensure fuel is getting to the bowl...remove the bowl, attach fuel line and turn fuel on...there should be a good stream coming into the carb...messy, but you'll know for sure the carb is getting fuel.


If that's all good and you're sure the jets are clear (including the little pilot jet set deep inside next to the main jet) then I'd ensure you're getting a good engine pulse. Hold your fingers over the intake and crank the motor...you should feel a pretty good pull...if not then you're not generating enough negative crankcase pressure to suck the fuel out of the carb. Bad crank seals can cause this as can broken reeds...

 

That sounds like low compression when fuel gets spit out the back of the carb,floods,fouls plugs,etc. One other reason for this is crank seals could be leaking, not allowing fuel to be drawn in. Fuel/air /oil mixture is then compressed in the bottom end up,shoots up the transfer ports to the top of the cylinder for ignition,but check the compression first and go from there..

 

Okay I'm going to check both methods from Dirt Devil and old Polaris Tech I know I have some sort of compression because the pool start has a lot of pressure on it my whole thing with this bike is I bought it so cheap that I don't really want to put out any money unless it's easy fix it's a it's a shame the bike has some good stuff on it I probably say another $400 to $500 can have a nice bike but that's Craigslist for you I feel bad for people that buy expensive stuff and it don't work I knew it was a hit or miss