fuel sprays back out carb??

[benb1984]

hey i got a lifan 125 in my atc70 its blowing fuel out the carb i got the motor 2nd hand not running, so know little about its past, it has low compresion, and it is definatly spraying fuel back out of the carb, if u put your hand over the mouth and kick it u feel it blowing as much as sucking.. like a bad intake port, but i have tryed 2 heads? could the carb be doing this? im gonna re seat the valves tommorw and see if that helps, although im sure they and the timming are fine...
any ideas or suggestions would be great

[SWIGIN]

Motors are basically just air pumps. Yours has a bent or hanging open intake valve, or you timing is WAY off.

[benb1984]

yeah.. i dobut its the timming, as far as i know its never been touched except by me today when i changed the heads.. so ill re seat them and see if that helps.. ill post some pics tommorow..
i had to change my header pipe to a shorter 1 that wasnt quiet as round or long as the 1 that came off the engine.. maby i need to match port these? do u think this could cause it?

[xr132]

I'll just about guarantee you that your valves need adjusted, your intake valve isn't closing. My Z50 usedta do the same thing!

[SWIGIN]

yeah.. i dobut its the timming, as far as i know its never been touched except by me today when i changed the heads.. so ill re seat them and see if that helps.. ill post some pics tommorow..
i had to change my header pipe to a shorter 1 that wasnt quiet as round or long as the 1 that came off the engine.. maby i need to match port these? do u think this could cause it?

Look, you asked for help I told you the main 2 reasons this will happen then you ask if the head pipe could cause this?

I have seen this in the past, my first post IS 90% of the time the reason regardless what you think.

[benb1984]

sorted it all out today.. was the valve gap, even when it was supposed to be closed it was holding open slightly. at least now i know how the whole head works.. night and day differnce it made too, idels prefect now has great low end power. still needs the carb tuned up, some new oil and then just chasing a new tyre now so i can really try it out

thanks for the help guys..

[xr132]

Good ta hear! I figured that'd fix er up!

[miajosh]

bent valve. way off timing, or abnormal wear on the cam and or rockers. i know this cuz my 86 200x is doing the same thing n when i tore it down the cam lobe is aoblong and the rockers are almost gone. motor probably runs but dont rev up to its full rpm and feels like its missing power. cuz thats what my trike felt like . if cam/rockers r worn u need to check oiling passages n make sure there not cloged n replace whatever is bad. also coulda happened due to a bad overheating. let us know what u find