Problem running a Lifan 152F motor

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CeeBee

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Jul 30, 2019
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Hello,

My son has Baja mini-bike and it has a Lifan 152F motor installed on it and we're having problems keeping it running. It (the minibike) was bought unused from someone about 3 years ago and mostly ran great but also ran very rarely as he was busy with other activities. We've winterized it correctly every fall and it's started up and ran without issue the past few springs. This year we tried it last week for the first time and we could get it running with the choke on and throttle at about 50% but as soon as we slowly turn the choke off it dies and backfires a bit, despite giving it a bit more throttle.

We've put in new gas. We've changed the oil. We've checked the spark plug and confirmed it's gapped correctly. We've removed and disassembled the Huayi carb, cleaning the passageways and orifices, and ensuring they were all open. None of this seemed to help, and I'm not sure where to turn next.

Is it a timing issue? Or is that even possible on this engine? Is a valve stuck? I'm at a loss.

Would anyone recognize these symptoms and be able to push me in the proper direction for a fix? Myself and my son would greatly appreciate it.

C
 
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FOG

Well-Known Member
Mar 3, 2019
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Even tho you cleaned it the pilot jet is still plugged. On small motors the jets are very small and when you add modern gas to the mix blockages are just a matter time.

I have a Chinese quad around here for the grandkids that does the same thing, only I have to pull the body and handlebars every time it plugs just to get to the carb! I don't know how many times I did that when one day, in absolute desperation, I tried a gas additive called Sea Foam to the gas tank.

1 oz per gal and it was just about a miracle! One pass down the block cleared that jet and despite periods of storage in between grandkids it hasn't plugged since.

I don't normally believe in all the hocus pocus hype around additives, but I will say this, when I fill the 5 gal jug that feeds the various toys around here the next thing that goes in is 5 oz of Sea Foam.
 
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MotoMagz

MotoMagz

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Aug 2, 2010
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Yeppers! I cleaned a gc160 carb. On my power washer. At first had no luck. Then I remembered the emulsion tube behind the jet comes out. Once out omg it was caked. Soaking and fine wire cleaned it up. Started right up and ran a little ruff at first now it runs as good as new.
 
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CeeBee

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Jul 30, 2019
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Okay, we purchased a new (identical) carb from Goofit.us, and other than missing the throttle return spring which we were able to take from the old carb, it was an easy swap. Problem is, we're still having problems getting it running or keeping it running. I do have a couple questions that I hope someone might be able to answer...

1. The new carb has an adjustment screw on the side where the other one didn't. It looks to be a fuel metering needle screw that runs right into the throttle body after the throttle plate. What would this control, how should it be adjusted and when?


2. The governor bar came off and I have no idea how to adjust it; whether the flat end of the shaft it's attached to should be facing up or down. It seems to be able to rotate almost 360 degrees.


I can get it running fast at idle but it won't idle at a normal speed. Also, it seems best with the choke at half. Opening it all the way and it dies, fully closing it and it seems to run rich. Any help would be most appreciated.
 
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MEASURE TWICE

MEASURE TWICE

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Jul 13, 2010
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You say you can run with the choke on, maybe then air leak as was said may be whats wrong.

Also for fuel air mixture screw, opening (CCW) the screw you will get richer mix. Some carbs have two needle valves, one for idle which if I am right is further down the throat of the carb just past the butterfly (throttle), and the other for above idle speed the needle valve is between the airfilter and the butterfly (throttle) valve.

A float type carb will not have enough fuel pressure to work if the float is not adjusted right. A float too high will not have the cycling on of the float valve often enough to have the fuel high enough to have the right pressure. If the fuel tank is mounted too low for a gravity feed pressure is also reduced. Seeing the fuel flow as a test into a metal can with the output of the tank hose should tell if pressure and volume is good.

Found this on adjusting governor, but for your brand nothing specific. Maybe someone else know where to find a pdf file or web page with that brand trouble shooting and adjustment. In any case the picture you post shows the linkage with a few holes for changing adjustment of the governor. Where the arm and the shaft from internal of the engine should be aligned I do not know.

https://www.smallenginesuppliers.com/shop/html/governor_adjustment.html

Seems that this would not be the case for your situation but for a too rich condition: My Briggs 3.5hp 4 stroke would not idle. In perfectly calm clear weather I pulled off the air filter and it idled. I then switched from the foam airfilter to the pleated paper airfilter and that allowed it to idle slow. I had to get some parts to fit the paper filter, but used on ebay were cheap.
 
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