lumpy at low revs

[Jester]

Hi, I am borrowing an 84 fj1100 of a friend at the moment as my CB750 is a hateful piece of garbage and I may be buying it of him but it has a couple of small issues. The main one is it runs very lumpy at low revs and doesn't seem to be firing on all pots, when the revs are higher (about 4-5k) it runs like a dream, any ideas what could cause this? If it's an easy fix I could very well buy it off him, they are just so comfortable and comfortless to ride.

Thanks in advance for any suggestions you guys or girls have.

[racerman_27410]

many times a thorough carb cleaning is all the carbs need to be made to run great again.

David R has a great writeup on doing just that and tuning the carbs properly afterwards.

http://www.fjowners.com/index.php?topic=655.0


Kookaloo!

Frank

[Jester]

Thanks for the very quick response, looks like I've got something to do in the garage tomorrow, which is cool as it's forecast for rain most of the day

[racerman_27410]

Thanks for the very quick response, looks like I've got something to do in the garage tomorrow, which is cool as it's forecast for rain most of the day

take your time and have fun !   the bike will reward you for it 


Kookaloo!

[CPTKEB]

Check the boots on the spark plug wires.  Sometimes they vibrate and unscrew from the wires.  I always "preload" mine by installing them with pressure that makes them want to tighten instead of loosen.  The resistors in them maybe bad as well.

[SlowOldGuy]

Sounds like clogged idle jets.  If you bump the idle jets to 40s, they don't clog as easily.

DavidR