SOHC.co.uk Forums > CB500/550
CB550 Tuning Advice
Neilw:
--- Quote from: deltarider on October 21, 2026, 08:57:16 PM ---Now bring the rpm down to say 1150 and then let us judge the sync.
--- End quote ---
Cold start this morning with the Choke on. Wouldn't start unless i blipped the throttle, and then would only stay running if i held the throttle open, which i did to warm up the bike.
I then switched the choke off (down position), and the bike immediately started running smoothly. I let it run for a while, it spat once or twice and then died about a min later. Started immediately without choke and idled quite happily with a few spits.
https://youtube.com/shorts/DL4JK8qOT2g?feature=share
Idling at 1200 rpm thereabouts.
I don't think i'll be taking the carbs off now, so I'm going to put the airbox back and air filter to see what this does.
Other than the throttle screw i've changed nothing - airscrew is still 1.5 turns.
K2-K6:
It may not be cold enough ambient to need full choke at this time of year in starting it. Worthwhile trying at 1/2 to judge effect.
Many bikes of this era have no throttle interaction with "choking" application, its just down to you to open the throttle a little, as appropriate, to balance demands at this cold start phase of running bikes like this. That's entirely normal and expected.
The end of line SOHC models variously had the throttle and choke linked to give the effect that you're doing manually here.
It does sound particularly good in running and cylinder to cylinder parity. If anything, it's "hunting" slightly (a little excess fuel at that independent running point) which is detectable in minor way.
A couple of miss/stumble hiccup heard, likely to be the plugs having not fully warmed from riding out on it (typical if just standing with no load ) that should disappear when all up and running.
As you note, fully assembled intake system to be installed, then see what you've got at that point.
It is very smooth though. Any competent workshop would be proud of that result.
Bryanj:
The 500/550 with those carbs need choke on to start but almost immediately back to half after starting and fully off fairly quickly, unless you are trying to ride in sub zero temperatures and i for one am too damned old for that!
Neilw:
--- Quote from: Bryanj on Today at 11:14:22 AM ---The 500/550 with those carbs need choke on to start but almost immediately back to half after starting and fully off fairly quickly, unless you are trying to ride in sub zero temperatures and i for one am too damned old for that!
--- End quote ---
Lol, this bike will only see summer temps, no cold or wet riding for me!
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