Hi All,

I have an 87 Trail Boss 250. It started and ran fine when I bought it a year ago. For the past month or two it has gotten progressively harder to start and now seems not to want to start at all. During the past few weeks of difficult starting, it would re*start fine when warm, and always ran great once started.

Over the past few days I have done the following:

* Drained gas and replaced with fresh gas
* Cleaned carb (it looked fine when I was "inside")
* Verified spark OK and replaced plug
* Replaced dry*rotted intake boot with new
* Tested compression * ~110 PSI

My Clymer manual doesn't give a spec for good compression * is 110 PSI OK? Was tested via pulling on recoil starter, b/c my starter motor is bad, as well...

Any help/insight is appreciated.

 

Take the exhaust off and see if you drain any gas out of it.

 

Removed the tail pipe * sadly, no gas inside...

 

recheck compression with the throttle wide open.

 

I'm not sure about your bike in paticular but some bikes will have hard start issues once the valves start to get out of adjustment, especially when it's cold.

 

250 Polaris are 2strokes and have no valves

 

ftwflh, initial compression check was done with throttle wide open. That was how the Clymer manual said to do it. IIRC, I actually measured with throttle open and with throttle closed, and readings were the same. FWIW, I turned the motor over while head pipe was off and the sound of the piston moving in the cylinder seemed to be a strong sucking sound (I realize that's not a very technical diagnosis).

 

Replace carb needle and seat, adjust air fuel mix to 1.5 turns out, bet it runs much better

 

tw1st3d1, are you talking about the float needle and base? I would think the "main" needle doesn't really matter until the throttle is opened. Fuel/air mixture makes a little more sense to me for starting/idling conditions.

 

i would bet the crankshaft seals or bearings are bad. a cold motor required a richer fuel/air mixture. the seals being bad would let excess air in causing it to run lean.