SOHC.co.uk Forums > CB500/550
CB550 Tuning Advice
Neilw:
I disassembled all the carbs, removed everything, and used carb cleaner and compressed air to clear all the passages and jets, making sure no rubber fragments were left.
I've reassembled everything, including the new hoses and the new O-rings, etc., being particularly careful not to pinch anything and to lube with silicon/red grease.
Before bench sync, I've spent the afternoon getting the float levels right and testing with the clear tube method - and guess what, I'm getting small rubber fragments again on carb 3.
I've taken it apart, checked every new o ring and there is no damage anywhere, i just don't know where the contamination is coming from!
I'm going to give all carbs a final flush with fresh petrol and hope that somehow resolves matters, but honestly I can't see how when I can't find the source!
The only thing i can think is that the new hoses have some residue from manufacture in them.
Any other ideas?
K2-K6:
Are you supplying from auxiliary fuel feed ? Not the bike's tank.
Neilw:
--- Quote from: K2-K6 on October 19, 2026, 07:05:40 PM ---Are you supplying from auxiliary fuel feed ? Not the bike's tank.
--- End quote ---
I'm using a clear auxiliary tank with clear tubes.
K2-K6:
Logic would be there's something caught somewhere inside the carbs and their fuel distribution, but puzzling as you say.
A suggestion to consider, if you've a steam supply (wallpaper stripper or the like of) you can make a small nozzle out of something like brake line pipe, then blow steam through all the orifice and pipes to see what comes out.
It's something I've used before in chemical lab work to clean various apparatus of debris as it'll usually free up anything stuck inside crevices etc to flush out comprehensively unwanted contents effectively. That can be "tarring" or residue stuck to surfaces you can't see.
McCabe-Thiele (Ted):
You have probably thought of this, if you cut the hose to length did you use a very sharp knife or a Junior Hacksaw, could it be coming from the raw cut.
Sometimes also if the hose is a tight fit it can cut when being pushed onto the metal connection points.
On my 400 & 500 I have fitted Aeroline fuel filters to try to minimise the risk of any debris reaching the carbs.
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