Lifan motor fuel problem

[Hondact110]

Hi,
I have a ducar/lifan 125 pitbike and it hardly runs. You need to hold it wide open and when you do this it still hardly revs, there is no responsiveness from the throttle either.

I have cleaned carb, done the valve clearences and changed the oil.

Thanks!

 

[my67xr]

Welcome to Miniriders,

Drop in and say hello in our Introduce Yourself thread too while you're here.


Sound's like the port's or the jet's are still blocked?
When you pulled the jet's out did you make sure the hole's down through the middle of them are clear?
Sometime's you need to poke a single thin strand of copper wire though the to clear out any gum/varnish that's built up from dried up fuel etc.
Also check the hole's that run across the jet's that they're all open/clear, especially in the emulsion tube where the main jet screw's into.
At the bottom of the thread's in the carby base where the pilot jet screw's in, make sure you can see light through to the bore of the carby, if this is gummed up then the bike will be very hard to start, and you'll have trouble tuning it.
And when you have the carby apart, remove the mixture screw and blow some compressed air through the carby, especially the 2 or 3 small hole's on the air filter side of the carb,
You should feel the air coming out one of the hole's in the bottom of the carby.

What sort of carby has it got on it?
And how many turn's out is the mixture screw ?
Are you using a clean foam filter, with filter oil on it ?

Cheer's , Craig

 

[Hondact110]

Thanks for the reply,
I have cleaned all the jets out and you can see through them. It has a just a stock carb, not sure what type but it is not and for carb. But the mixture screw do you mean the idle screw? Because we haven't touched that.
It has a foam filter with no oil. But when it's running fuel sprays into the air filter as well which is bad, I have adjusted the float height but that didn't hepl.

Thanks

 

[my67xr]

Fuel spraying into the filter sound's like valve clearances need adjusting ?
What are they currently set at ?

The mixture screw is the screw that you turn in or out to adjust when tuning it, It let's more or less fuel into the fuel/air mixture.
It's not the idle speed screw

What marking's are on the carby ?
It may have something like JinKe, ShengWay or ...

 

[Hondact110]

Valves are set at .05.
The carb has "K F Standard Japan" written on it.
Will have a look at the mixture screw tomorrow.

 

[my67xr]

Is that valve clearance setting mm or Thou (") ?
Either way it's wrong

Carby is a Keihin china copy, mixture screw is the flat headed one on the left of the central idle speed screw (philips head)
Turn the screw in clockwise, while counting how many full turn's in.
Eg, 1 1/2 turn's, 2 turn's, 2 1/4 turn's et

 

[Hondact110]

It's in mm.
Yep that's pretty much the same as mine. I will give the mixture screw a go.

 

[Hondact110]

Oh yea and the valves are set at 0.005mm not 0.05. Last out a 0 haha

 

[my67xr]

Valve clearance is way too tight then.
Clearance's should be .003" (.076mm) on the inlet, and .004" (.1mm) on the exhaust

 

[Hondact110]

Ohhhh just realized that the valves were at 0.005" not mm....... Will have to fix that, I set them to 0.05mm thinking for some reason that it was 0.005"

 

[Hondact110]

Will do that tomorrow thanks heaps for all your help!

 

[my67xr]

.005" will be fine, maybe a little tappety.

This is a different carby, but with the jet's out, check that you can see light through the bottom hole, that's where the pilot jet screws into

ds80mikuni20mmmainjetpilotjethole.jpeg Photo by xrfairmont67 | Photobucket