Hi guys I'm having a problem with my bike misfiring. I've checked the sparks to the plugs and all good sparks. And I've stripped the carbs and cleaned them and it's still misfiring??? [emoji848]

More detail, particular rev range, one cylinder or more, when did it start.

I think it's only on one cylinder don't know which one. And it only misfires on tick over at 1,300 RPM and it's done it ever since I've had it


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If it only happens at idle, I would suggest either a pilot jet is miss adjusted or blocked. You need to identify the offending cylinder and try adjusting the mixture screw. Did you set the mixture screws when you had the carbies off.

Yes it said in the book two turns out. And I put the carbs in an ultra sonic cleaner


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My NC30 does not have the smoothest idle and is not jetted perfect for the aftermarket mufffler, but it idles without stalling so I am happy. If yours idles without stalling and the idle is just a little rough, then you might want to try balancing the carbies.

could be a small vaccum leak one one of the carb rubbers or the fuel tap vaccum hose casuing weak mix on affected cylinders.

my nc30 idled like a swiss watch...

Is it firing on all 4? All 4 headers getting warm? (spray some water on them)

One of those cheap infared hand temp detecters helps a lot with this sort of thing, you can pin down which cylinder is miss-firing quite quickly. As its sometimes hard to tell by hand the offending cylinder. Especially as they all appear to be very hot but you can quickly find out a difference tween 100° and 200° with that tool. Just aim at your header pipes one by one.

yep infrared thermo is good thing to look at manifold temps.

lots of good suggestions so lets go back to the basics first.

for a good idle you need

1. valve cleranaces to be in spec.
2. no vaccum leaks on carb rubbers / fuel pipe vaccum takeoff / balance screw ports.
3. carbs setup and balanced properly.