Help! the bloody thing won't idle@#$%^

[Citroenjunkie]

My son has been "lent" a chinese motorcross style mini bike.

The bike was bought in December and was ridden no more than a dozen times before arriving on our doorstep.

When we took it out for a ride we discovered it won't run for any length of time. It starts first pull, pulls away cleanly runs for a short time then cuts out, no warning, loss of power, misfiring or anything. It will also not idle no matter how much I fiddle with the cable adjustment or the idle screw on the carb.

At first I thought it was because the engine was cold, then because the young feller was being a bit gentle, but it does exactly the same thing no matter how you ride it-gently or flat out, hot or cold. It runs for a short time then dies.

I took the motor out, stripped the carb, which was full of fine grit, cleaned everything carefully, put it together and...it was exactly the same.

I cannot be beaten by something this simple, it is just not right!

Any suggestions would be appreciated. Thanks guys:rolleyes:

[JimO]

i think the main problem is its shit

[BigAl]

Try the easy remedies first. Especially if it has a chinese spark plug, replace with a new NGK. 2 strokes are very hard on plugs, if the mixture is not 100% right.
Are you running a synthetic 2 stroke oil, don't run chain saw/mower oil.

[Gadgit]

Heres a few surgestions for ya
The fuel cock (tap) on the side of the carb may need cleaning out they have very small inlet/outlet holes in them. and the fuel tank outlet is also something to look at cleaning. But what it dose sound like is the fuel tank breather is blocked (which is in the fuel cap) good luck.

[Citroenjunkie]

The tap is of course the only thing I didn't think of. Thanks I'll give it a try, the sparkplug too :niceone:

[skidMark]

The tap is of course the only thing I didn't think of. Thanks I'll give it a try, the sparkplug too :niceone:


Yup probably the sparkplug.

The 4 stroke chinese bikes run an A7TC NGK, but i think 2 strokes take a different plug.

Sounds like a plug problem to me.

SM

[daytona 2]

im suprised it works :gob:

[SHELRACING]

im suprised it works :gob:

So please tell us what you did then!

[Citroenjunkie]

Well done sir!

The tap has been suitably modified and now allows fuel flow which would even be sufficient for a fairmont!

And yes the bike is now running perfectly!

Thanks once again:done: