Topic: Running a little lean

[volz1fsu]

I have a 500 engine in my '75 CB550 for the time being and it seems to be running a little lean on the carburetion.  I fully ported and polished the head on the engine, also I am running a very non restrictive exhaust and pod filters on the carbs. 
The carburetors are for the 550 engine so I figured they are probably jetted richer than what the 500 carbs were but I don't know if thats true.  Anyway, they are not rich enough for my engine.  I drove it and when I get on the throttle it hesitates quite a bit at mid to full throttle.  I checked the plugs when I got back and it sure seems lilke the engine is running lean, not bad but noticable on the plugs.  So what should I do?  Raise the needles a notch or throw in the next bigger jet size?  Seems to me I should throw in bigger jets because that would be mid to full throttle.  Has anyone had this problem?  I can't imagine anyone not going through something similar with a cb750 after performance work.

[TwoTired]

Which 550 carb set up do you have?  Most have smaller jets and bigger needles in them as the larger displacement sucks on the carbs harder.

You have smaller displacement, plus pods which both make the vacuum in the carb bore less.  You'll need bigger fuel orifices to compensate for the reduced flow.

If you still have good 500 carbs (627B), use them as a start before fine tuning.

Have you done a WOT plug chop?

Cheers,