KX 250 strating issues

[duckracer]

All,
I picked up a used KX250, and my killer deal is not looking that killer anymore.
I got the bike to start once when I first brought it home but now it will not start at all. I checked the spark, but it seems weak. It is a blue spark, just very small. I have fresh fuel mixed at 32:1, and I can feel the air being pulled into the motor when I place my hand over the carb inlet, and if I kick it for a bit I will get fuel comming out of the pipe where it joins the head, and the plug will be damp. I removed the carb and cleaned/blew it out and set the float. while I had the carb off I checked the reeds and found one was torn so I replaced them with Boysen pro reeds and rejetted the carb 4 sizes smaller. I checked the compession and I get 120 to 130 PSI, which seems a bit low to me. I have not tried the old 4 wheeler push start yet and will try that today.
Any help would be greatly appreciated.

 

[mideastrider]

You say you checked the spark. But have you put a new plug in? If you see a weak spark with plug out it may not spark at all under pressure.

 

[88'cr250r]

coil or get some sand paper and clean the flywheel

 

[CRazy250]

please dont drag it behind a four wheeler, even if it does start while dragging it whats the point? you know your bike isnt running right so doing that isnt going to make it any better. besides its not going to run at its peak power. you already have a serious problem so dont make it worse, id say throw some new rings on it and have sombody check out your electronics and get your carb jetted correctly and go from there. check for any air leaks in the carb boots and any gasket surfaces. you could also have bad crank seals.

 

[88'cr250r]

yea denfinlty need a new piston 120 psi wow

 

[gthoma23]

yea denfinlty need a new piston 120 psi wow

had a bike w/ lower compress than that and ran great. once it gets to about 105 i'd be lookin for a new piston. it would still start w/ that low of compression.

 

[89RM]

I'd try a new plug...maybe even a hotter one (on NGK plugs lower number = high temp).

 

[dirt bike dave]

Fresh gas (drain all the old stuff out of the tanks and carb)

New plug

If those don't work, your likely culprits are low compression or bad reeds.

A warped or cracked reed can make a cold two stroke nearly impossible to start.


Also, it could be your starting technique. After putting in the fresh plug and gas, turn the gas on. Lay the bike on its side for about 10 seconds. This gets gas into all the circuits of the carb. Pick up the bike. Turn the choke on. Kick over the bike SLOWLY two or three times to prime it (do not twist the throttle at all). Find top dead center. Do this by kicking very slowly and feeling the compression. Just as the compression starts to ease up, the piston is at the top. Return the kicker to the top of its stroke and kick as hard as you can. DO NOT twist the throttle. If no luck, return to TDC and try again. Some bikes like a tiny bit of throttle on cold start, but usually not much, and none is best to try at first.

 

[2strokerfun]

You compression reading is not really accurate if you're doing it cold. It will likely be a little higher after engine runs and is warmed up.

 

[lineskier24]

please dont drag it behind a four wheeler, even if it does start while dragging it whats the point? you know your bike isnt running right so doing that isnt going to make it any better. besides its not going to run at its peak power. you already have a serious problem so dont make it worse, id say throw some new rings on it and have sombody check out your electronics and get your carb jetted correctly and go from there. check for any air leaks in the carb boots and any gasket surfaces. you could also have bad crank seals.

Yea, defiantly not a good idea to force a jump. my piston literally shattered in my old yz125. huge problems!