SOHC.co.uk Forums > CB500/550
First Start Highs and Low!
deltarider:
Oddjob, all the above, is what I also do occasionally. However every oldstyle CB500 has a carb setting that you can start riding with the chokeflaps fully reopened. Just keep a slightly raised idle for the first km or 2. If you need the choke in combination with a raised idle riding it's indication you've been tempted to turn out the airscrews too far. Period. Too far can be even a small increment of 1/8 of a turn!
Skoti:
Hold on tight folks for yet another long thread.
Here we go again with more on the air screw myth...
Neilw:
Just an Update - and honestly you just can't make this up!
The overspill has gone, as far as i can tell from carb 2. UI dropped the height of the external fuel tank and got set to go.
Tried to start the bike, but it just wouldn't fire. Cleaned the plugs and went to go again, but the Battery is dead!. So I had to order a charger and let it charge overnight.
Full of hope this morning, I reinstalled battery and fired her up, of rather it didn't want to fire. Popped plug 4 out and there was no spark, tried 3 and there was. put 3 back, started the bike and it sort of jumped into life briefly before dying, now no spark there either.
I've spent the morning testing and it seems it could be the coils, i'm not getting the readings the videos say I should, but as the language is not consistent across the videos i don't 100% know if i'm checking the right wires with the multi meter at the coil. Basically, I get 0 when connecting the MM to the yellow and black/white wire coming out of the coil and the same for the Blue - Black/White combination. Is it possible for both Coils to fail at the same time?
So i can't even get the bike started to see if the carbs are any better! FML lol!
deltarider:
--- Quote from: Skoti on October 02, 2026, 10:14:03 AM ---Hold on tight folks for yet another long thread.
Here we go again with more on the air screw myth...
--- End quote ---
That's not very friendly of you, Skoti. Please read p.29 in: https://www.honda4fun.com/dwnload/Owners-Manual/CB500-K1-Owners-Manual.pdf
I've cured quite a few bikes, by bringing the idle to 4-4,5% CO again. That's about mid range on a CO-tester of that era.
What I presume - but it's only a presumption - is that owners, today oldtimers themselves, are more interested in a nicely purring idling than in good driveability. Maybe the only ride they do is: bring their bike on a trailer to a show, let it idle, harvest compliments from bystanders on how well it runs and then return home, bike on the trailer again.
Anyone who doubt my posts, can try it out for himself. After extensive testing, my airscrews differ in position, but they average 11/16 turn out. That's damned near Honda's 1 turn out +/- 1/8, dont you think? If I go leaner with those air screws, I'll have whitish spark plug noses at 3000-3500 rpm in 2nd and 3rd gear. If I turn the airscrews a tad in again, all is well again. Can you explain me that? Please refrain from negativity, Skoti. Me thinks, we have had enough of that.
Neilw:
--- Quote from: Neilw on October 02, 2026, 11:38:00 AM ---Just an Update - and honestly you just can't make this up!
The overspill has gone, as far as i can tell from carb 2. UI dropped the height of the external fuel tank and got set to go.
Tried to start the bike, but it just wouldn't fire. Cleaned the plugs and went to go again, but the Battery is dead!. So I had to order a charger and let it charge overnight.
Full of hope this morning, I reinstalled battery and fired her up, of rather it didn't want to fire. Popped plug 4 out and there was no spark, tried 3 and there was. put 3 back, started the bike and it sort of jumped into life briefly before dying, now no spark there either.
I've spent the morning testing and it seems it could be the coils, i'm not getting the readings the videos say I should, but as the language is not consistent across the videos i don't 100% know if i'm checking the right wires with the multi meter at the coil. Basically, I get 0 when connecting the MM to the yellow and black/white wire coming out of the coil and the same for the Blue - Black/White combination. Is it possible for both Coils to fail at the same time?
So i can't even get the bike started to see if the carbs are any better! FML lol!
--- End quote ---
Confirmed I have cooked the Primary circuit, most likely becasue i left the key on while diagnosing the starting issues. New ones on order,
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