Forum

[Exile]

Continuing with my carburettor problems: I have refitted the carb with the
new manifold hose from Hitchcocks. Unfortunately, the machine is still running
rich even though I adjusted the throttle needle stop to a leaner setting. The
bottom end is running rough, all sputtter - pfft - cough and spit and then cuts
out. The throttle is not very responsive from tickover and cuts out more often
than it revs up.
Right now, I'm somewhere close to this place:


So, any ideas anyone? Right now I'm considering moving the throttle needle
stop back to where it was and re-installing the PAV.

[JOHNNY SINGLES]

Did you adjust the throttle stop screw or did you mean the idle mixture screw. Adjusting the throttle stop screw will achieve nothing but faster idling speed.
If you have the correct jetting for your bike set up,the float is set to the correct height, there are no air leaks, the timing and tappets are correct and the correct plug type the bike should run correctly. A little rich is better than a little lean. you could also fit a hotter plug.

[jaffa90]

Is the float needle shutting off the fuel supply at the required level, is the valve clearances ok, have you a good spark, also is your exhaust clear.

[Exile]

I know what to do with the air screw and throttle stop screw for adjusting idle and tickover. That's not the problem. It was running rich so I adjusted the throttle needle to a leaner setting. The bike is virtually new despite being 8 years old, so I would assume that the valves etc. are OK having only covered 2500 km. Float height could be a possibility.

Spark is OK.

Timing? It was OK before I rejetted..

[Pony]

Having a similar problem myself at the moment. I rejetted the carbs following the PAV removal and exhaust change together with air filtration system removal. The bike was running far to lean. As you now have better exhaust flow, your bike should be running lean, like mine was. I followed the advice over the phone from our hosts and replaced all of the jets along with the throttle slide. Now its far too rich. Tried tuning the carb as per the tech notes but the air mix screw is out nearly all the way and ran out of adjustment. Hope you solve your problem. Hopefully if you come up with an answer it might help with my set up. I've forgotten which way the needle needs to go to lean up the mix and am feeling a bit thick tonight. So any pointers would help.

[Pony]

you describe it coughing at idle. If it's coughing fuel back through the carb, it usually means it's too lean.

[Exile]

Pony.. I checked with the forum before I moved the needle stop. Here's the drawing I made..

[Norm]

Messing with the needle position has nothing to do with what problems you are having, the needle circlip position only really effects running above 3/4 throttle settings. Pull the pilot jet out and clean it for starters

[jaffa90]

Assume nothing, do you have valve/tappet clearances ? Can you see the colour of the spark and hear a crack?

[simon]

Float level?