Went out on the bike saturday, to stay overnight and come back last night. Half way on my journey on saturday the bike started to miss-fire / run rough. Sounded like it was running on 2-3 cylinders then once above 8,000rpm it would pick up and pull to redline. If i pulled the clutch in, the bike would rev freely. So under load is the issue.

I was riding back and i thought it could of been plugs / ignition side of things, or even blocked main jets as it rev's clean off load.

When i got home, I must have drove about 40miles at 60mph, i felt the exhaust & it was cold. The temp guage on the way home was not far off the red line, im running a normal radiator, which isnt blocked off.

I was thinking that maybe the bike has no thermostat, or is stuck open. Therefore not allowing the bike to get up to temp, and this could be causing the rough running due to keeping the block temp down.

The last time i had ridden the bike, was in december and we thought it began to carb ice up & run rough due to the -2 temp and the fog, throw in the 60mph wind and it started to run rough.

What do you think.? For 15miles yesterday it ran fine, and i could overtake. Just went to overtake again and it started to fire up on 2-3 again, if you held the throttle it would clear up and be fine,then the next corner coming out of it, it would splutter away.

Or am i looking at a straight carb clean & 4 new plugs.?

Regards,

Alias

best thing to do is do some simple checks,make sure all spark plugs are sparking......check each header pipe and see if they are hot...if so then it's firing on all 4.

does it happen all the time?if so i would be inclined to say it's carb related.



william

Had the carbs off tonight, 3 pilots blocked, 2 main partially blocked. Could be the reason for this all.

Snapped a screw on the rear left carb on the diaphram bit, should not affect it, but have put out a post for a replacement if cheap enough, then swap it out if it arrives.

The main jets are 115..

Have an Ethos full system, standard airfilter.?

depending on what model nc30 it is i would have expected at least 118/120 main jets with running the full ethos system.

usually the rear two carbs run larger main jets as standard except for the r3k model(same front and back) and uk model(smaller rear)

this could be the issue with your bike,try fitting larger main jets and see what happens.i was running a full ethos system with a slight mod to the air box and i was running 120/122 if i remember correctly and it ran very smoothly throughout the rev range.



william