SOHC.co.uk Forums > CB350/400
The elusive surge
philward:
--- Quote from: 400 Cafe Racer on January 12, 2022, 02:32:49 PM ---
--- Quote from: philward on January 11, 2022, 09:17:38 PM ---
On my 400F the air filters and exhaust are non standard and I have an Innovate Air / Fuel Ratio guage already fitted which was very useful during re-jetting and setting up under actual running conditions on the road. The settings I have used are to deliver best power, torque and engine temperature, with no specific regard to economy or plug colour.
--- End quote ---
Dennis, I'd be interested to hear how the Air/Fuel physically fits on a 4 cylinder 4 carb bike?
--- End quote ---
Hi Phil,
To avoid distraction from Alexs' post I have put a link to my post showng recent guage additions. I have just added a final one to show where the sensor is fitted in the intermediate pipe.
Dennis
http://www.sohc.co.uk/index.php/topic,26987.0.html
[/quote]
Thanks Dennis - seems its not pracrical for me - My 500/750 have standard exhausts and my CR750 has 4 into 4 race exhaust. (all of which I'm not prepared to weld bits on obvious reasons) - thanks anyway
daz-j:
Just to report back I seem to have cured the problem ;D - I took the carb bodies to work and gave them a good blast with compressed air, fitted the new seals, and reset the float heights. So one (or a combination?) of these made the difference - my gut feeling is the float heights were the culprit.
Thanks Alex and everyone, hopefully I won't need to take those carbs off again anytime soon!
Nurse Julie:
--- Quote from: daz-j on January 15, 2022, 07:44:58 PM ---Just to report back I seem to have cured the problem ;D - I took the carb bodies to work and gave them a good blast with compressed air, fitted the new seals, and reset the float heights. So one (or a combination?) of these made the difference - my gut feeling is the float heights were the culprit.
Thanks Alex and everyone, hopefully I won't need to take those carbs off again anytime soon!
--- End quote ---
I'm pleased you have them sorted Darren, well done.
400 Cafe Racer:
--- Quote from: daz-j on January 15, 2022, 07:44:58 PM ---Just to report back I seem to have cured the problem ;D - I took the carb bodies to work and gave them a good blast with compressed air, fitted the new seals, and reset the float heights. So one (or a combination?) of these made the difference - my gut feeling is the float heights were the culprit.
Thanks Alex and everyone, hopefully I won't need to take those carbs off again anytime soon!
--- End quote ---
Hi Alex,
Pleased it was straight forward to find and that you got it fixed . :)
All the best
Dennis
Alexrayz:
Hey everyone,
Just giving an update on the situation: Still not working atm.
The last actions taken were as follows: Did a vacuum sync which gave good results, smoother idle and no surges (or at least none happened while I was testing in in the shop). I still had revs hanging after giving the slides a quick lift. Actuating the slides the other way helped bringing it down. New issue though: Even without the idle screw acting on the slides the tick over is 2500RPM. No good.
My guess while vacuum syncing I lifted the slides too much. So I decided to get the carbs off again and redo the bench sync.
Did just that, also reajusted the choke's butterflies as they were not even. Put the carbs on again and it ran like crap again. Surges crazily and when it doesnt it can barely hold tick over at 1000rpm. Acting on the idle screw results in instant surges to 2500/3500 rpm. Still managed to sort of sync it at 2500rpm but without improvement.
Tried to lift the slides with the cable grip and it killed the engine immediately. I gave up after that.
I am starting to consider seeing a mechanic as I feel this is beyond my capabilities and knowledge.
I really struggle to see a consistency in the behavior and the right actions to take.
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