Running rough under 3000 rpm

[Craiginuk]

Hi all,  I have a 99 fzs600 which i bought with around 27000 miles on. It had been standing and was spluttering a bit below 3000 rpm. Took carbs off to clean and found one of the pilot screws was broken.  Could not get it out so fitted a 2nd hand set of carbs.


Runs beautifully above 3000rpm but is rough below. Just wondering if there is a common issue with fazers or is it just a case of needing to clean the "new" bank of carbs. They were supposedly off a recently running bike.


Have also changed plugs and plug caps but no difference.  After a ride all exhaust temps sit at around 120 - 160 deg C except for cyl 3 which is at about 80 deg. So i am guessing cyl 3 is not getting fuel or firing below 3000 rpm.


Thanks in advance! Craig

[Fazerider]

There's a chance the new carbs had some muck at the bottom and during transportation this has found some little holes to block. Have they been balanced and TPS adjusted?
The colour/wetness of the plug should tell you if cylinder 3 is getting flooded or starved of fuel.

[Craiginuk]

Thanks, yes did balance and set tps when i fitted them. I'll take number 3 plug out and have a look and compare against one of the hotter cylinders.

[unfazed]

Anything below 3000 revs on one cylinder is usually carb pilot circuit blocked

[Craiginuk]

Anything below 3000 revs on one cylinder is usually carb pilot circuit blocked

Yep, I'm suspecting I'll have the bank of carbs off again over the next few weeks... If time and weather permits, maybe sooner.