hi there.
basically ive had my cbr for 7 months now. in feb i decided to service it. i did the usuals, oil, oil filter, iridium spark plugs, air filter and coolant.
after the service it wasnt quite running right, it misfired ran on 3 cylinders on idle.
i posted on here and got a few replies. i got the carbs balanced as a few people recommended it.
it half solved it, it didnt do it as much.
today riding it to college, it started up normal, but now it only fires on 3 cylinders constantly below 3000rpm.
had few ideas if its not the fuel could it be my coils?? someone suggested new leads + caps??
any ideas/help from you ladies and gents would be much appreciated.
thanks
laurence

extra info. - nc29, r model, 110 main jet.

Have you checked the valve clearances? This should be done before balancing the carbs.

check plugs-leads

valve clearances where done at same time as carbs apparently.
plugs are under 1000 miles. + it doesnt change when you put diff plugs in...
and what im thinking is it might be fuel,
cos it only does it at low revs.
could my pilot jets be wrong coz as soon as you open the throttle and go above 3000 its fine??
cheers neway
laz

Your jet sizes should be:
Pilot - 35
Main - 105

Compression check might be an idea.

Are the correct sockets on the plugs? Had this problem long time ago - the bike ran like a tractor on 3 cylinders. I saw that i've mixed up the connectors from the 1st and the 2nd plug - the firing order wasn't right...

razor - just checked again theyr'e all on correct...
if it was ht leads or caps would the problem go away when revved, it literally only does it on tickover or below 3000rpm???
cheers again
laz

Here is a great way of checking where your problem lies.

Take the air box off and squirt some EZ start down the inlet of the offending cylinder when the bike is running. You only need a little bit.

If it briefly comes to life and runs on all 4 for a little while it means you have a fuel problem and need to check the carbs again. Could be blocked pilots or something.

You can tell if the cylinder comes to life by feeling the exhaust header carefully - it will get warmer.

If it does nothing then chances are you have a duff component in the HT setup.