Hi , Recently restored a Kawasaki GT550. I got it running, but is rough.
Ive replaced the plugs, caps and ht leads

Now my problem is that No3 is running intermitantly the bike idles up n down between 1000-1700 rpm and if left will cut out. Reving the bike up to 4000 seems to help but still sounds a bit rough(missing), rev it to 5-6000thou and the revs hang and slowly drops - which to mean seems to be saying that at that rpm the 3rd cylinder is running
I think is could either be:
- weak coil
-ive checked as best as i can for a vacume leak- and cant find one
- no split diaphram and slide appears to work well
- maybe low compression valves/ rings- although all seemed fine on rebuilding.
- checked the sparkplug, even put the old one in that started to cause back firing- due to firing even less often!....

The HT leads are new and are silicon types desgned for a car.

Anyone have any other tips?
-Thanks for all the answers added so far.
- Will double check the diaphram on that carb
- Carbs i balanced 'by eye' n 'ear' when i stripped them down n cleaned them - so they are in the 'ball park'
-bikinkawboy - funny you should mention that as my vacume hose is connected to No2 and i was having problems as the tap diaphram had become porous- looked fine until you sucked and got a mount fuel of fuel vapour 'YUK'. Anyway i have replaced the tap with a known good one- so No2 runs nice- Just No3 is the pain. lol