[mook13]

xr50 carb problems

Before I start tinkering with something, I figure I better ask. My nephews xr50 is running bad. When you start with the choke, it cranks up. Shut off the choke, give it a little gas and it revs up to full throttle on it's own and stays. You give it gas and it bogs and then right back to full throttle. Turn the choke on and it trys to stall, shut choke off , it idles, give it gas and it throttle all the way up and stays.
Also noticed the spark plug wire(plastic part over the plug) is cracked from a crash this weekend. and the air box has a little crack in it, it was sealed with something that looks like caulk from who ever his Dad got it from.
Is it something with the carb , like a float sticking? or would an air leak make it throttle all the way. What should I look at first?

[Asmith]

A Pinched throttle cable.

[mook13]

But throttle snaps back to original spot when you let go, the bike just says at full throttle

[michanic220]

i dout its a throttle cable problem. a motor revs to full throttle when you run out of gas, and shortly dies because it has nothing else to run on. so what your looking at is probly a fuel problem. check your fuel filter and lines, and shut off switch. which it probly isnt any of that, i'd look into your carb, its probly your float stuck up to where it wont allow any gas flow or a jet plugged up. clean the carb out, soak it in carb cleaner over night and blow out all the passages out with an air compressor, anything over 120psi.

[zak13]

a motor revs to full throttle when you run out of gas.

huh? ive always expierenced the complete opposite, motor not going past idle when its low on gas.

[michanic220]

it does on some motors and others it doesnt, dont know why just does. i mainly rebuild outboards so they wind up before they die, im assuming it could be the same on a DB or ATV but mine never wound up.

[michanic220]

but non the less, im pretty much possitive its a carb problem, you must have something pluged. if you mess with the fuel to air ratio you'll get stuff like that.