SOHC.co.uk Forums > CB500/550
550f running rich?
deltarider:
Depends. What is the prescribed position and what is yours now. I've changed the needle's position (CB500) out of curiosity and there wasn't that much effect, just like a Honda mec had said. I'd stay close to the original settings.
Leaking O-rings on the main jets have to be excluded, as well as accidently reamed slow jets.
Aftermarket air intake can make a difference, aftermarket exhaust hardly at all.
The correct fuel level in the floatbowls can easily be checked by applying this method: http://forums.sohc4.net/index.php/topic,185754.msg2151647.html#msg2151647.
Without having read all the above, make sure air intake is unobstructed, the airfilter element is good, meaning not moist or fouled by crankcase fumes.
DomP:
Standard for an F is 2nd slot from top so I'm proposing using the very last slot
*Little update, I did this today by extracting the needles through the top of the carbs while still fitted which is a whole lot easier. It then wouldn't start off choke which is encouraging as before it would start with no intervention at all. I made the battery a bit weak while trying so stuck it on charge chopine listening to the football. That's as far as I got, can't rush these things!
ozzybud:
--- Quote from: DomP on October 19, 2025, 12:57:14 PM ---Standard for an F is 2nd slot from top so I'm proposing using the very last slot
*Little update, I did this today by extracting the needles through the top of the carbs while still fitted which is a whole lot easier. It then wouldn't start off choke which is encouraging as before it would start with no intervention at all. I made the battery a bit weak while trying so stuck it on charge chopine listening to the football. That's as far as I got, can't rush these things!
--- End quote ---
Please remember after you change the needle positions in place or on the bench you will need to start the bike and get it warmed a bit and do a vacuum sync before test riding.
You will.never get the arm positioned in the same place. On the shaft it was before and your synchronization will be all.over the place.
If not synchronized it will mimic lean and rich conditions on the plugs after a ride.
I believe it is the most important step when tuning.
DomP:
Cheers Ozzybud, I'll make sure I resync them before going any further
DomP:
I've spent a few hours in the evenings pottering about with my 550, after dropping the needles to their lowest setting I re-synced the carbs and tweaked the timing a touch to be ever so slightly past the advance mark. Pleasingly it is now more difficult to start with no choke from cold which previously was easy even on cold days so hopefully if I get a chance to get it out soon I will be able to see how it runs, ive reset the aircrew upto factory as a base line to work from.
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