trouble starting engine

[tim85]

Hi, I am in the middle of trying to fix my brother's bike. It's relatively hard to start, and will not idle. I thought it might be an air leak so I gave the intake a new gasket and put an O Ring on the manifold. The carby itself is new and the jet is secured properly and the needle is properly set. Still no difference. The fuel lines are good, carby has fuel going through and the piston is getting fuel. However, at closer inspection I noticed that the piston isn't getting all the way past the intake. The piston does reach all the way to the top of the cylinder but about 1cm of the bottom of it is still visible through the intake. I've never had to do any repairs to an engine in terms of the piston, so I don't know if it is common for that to occur. I had a look at mine, and it goes up past the intake. This would be why it isn't starting too easily and not idling at all, right?

 

[SignedByMe]

Hello before you start doing anything first make sure there is a spark. To do this take the plug out and rest it on the head of the cylinder. If spark problem piston if no spark problem electrical.

 

[tim85]

I got spares anyway. I'll just switch plugs. Thanks.

 

[crassius]

unless modified, these pistons usually don't clear the intake port

often, if idle screw is all the way in & still won't idle, one needs to lean out the needle a bit

 

[tim85]

Thanks crassius, would that be higher or lower? I can never remember that one

 

[crassius]

one moves the clip higher to let the needle drop lower to block more fuel

 

[butterbean]

Idk about the idle screw on the cns or other carbs, but on the NT the idle screw needs to be at least 3&1/2 turns out.