Only starts with choke and no idle - RK NC30.

[neptune]

I have a RK NC30. It is completely standard, all cylinders are firing, electrics work, fuel is getting through but it will not start unless I use the choke. I turn off the choke and it has a shakey idle, fluctuating between 1600 to 1200 odd rpm and eventually drops down to 1000 rpm and then cuts out. When it is idling and I apply the throttle, it either cuts out or chugs before picking up or cutting out.

I cant see any obvious signs on what would cause this. All of the spark plugs are new and each have a good spark and each pipe does get hot. I have cleaned out the carburettors too but the problem persists.

Does anyone know how I can fix this? Can anyone help?

[Neosophist]

The symptoms you have match a very lean idle (hence needing the choke enrichment to start)

This is probably an air leak (check your carb rubbers are ok / seated properly, if you've had them off it is likely to be this)

Get a can of 'easy start' and spray it around the rubbers when the bikes running... any change in RPM and you have an air-leak.

Have you messed with pilot screws? they could be set very lean too. (reset the to factory defaults if so)

Also check for dirty pilot jets...

[Cammo]

Yeah I would do what neosophist suggest with easy start, and if that doesn't help it's carbs off time for a full clean and set to factory specs.

[SimNC30]

Mine has started to do this. It needs the choke to start if it's been left overnight or not running for any length of time, and then it eventually idles really low and cuts out - plus it sometimes does what you've descirbed when you open the throttle and it cuts out - aaah carbs! Mine also tends to do strange things on a run and i've decided to stip down and clean out my carbs, which i'm going to do next weekend - i hope it will fix the problem and i'll post my findings. I just need to find someone with an compressed air machine first.

[neptune]

Do you mean the rubbers between the cylinder blocks and the carburettors, the inlet manifolds? The standard jets are fitted and I haven't changed anything but I will double check the pilot screw. I will try the easy start tomorrow. The carburettors are such a pain to install. Not looking forward to taking them off again!

[wullvfr]

Do you mean the rubbers between the cylinder blocks and the carburettors

the carb rubbers,as neo said.usually if not seated correctly it causes a vaccum leak.because it is such a nightmare to refit the carbs it is easily done




wull