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CB200 carb issues

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Sesman:
Yep, at least that would indicate a load related issue. Eg spark break down under load…..or fuel….or something…

Sesman:
Hi, John. One thing I forgot to mention about the coil….dwell time. Are you sure the advance mech is functioning correctly? As the engine revs up there is less time for the coil to reach its steady state current. If the dwell time is such that the coil time constant doesn’t permit the DC steady state current to be established the HT side will falter. It’s just that at around 6k rpm I’m guessing you are approaching full torque and if the timing unit is not working properly neither will your ignition. For example, if the motor starts to hold back and die at 6k, but come back as the revs fall, it’s a good clue as to the problem. I’d strobe the ignition? Apologies if that’s already been mentioned

Sesman:

--- Quote from: Johnwebley on March 09, 2023, 03:27:48 PM ---
--- Quote from: Sesman on March 09, 2023, 11:29:58 AM ---Back on topic, was the misfire, holding back problem solved?

--- End quote ---



  not quite died yet,its been cold,so I have left it until it warms up.

BUT,thinking  ,at 6,000 rpm itis generating 100 sparks per second,using the 4.7ohm coil ,

 is that enough to make the coil refresh??
infact,at the red line of 9K,it should be having 150  bangs a second,.

I know it was hopeless  with a wide contact gap,reducing it to 12thou  certainly improved  the general running,but not increased  how high it revs.

does anyone know the spec of the original coil?

no details on either  DSS or  CMSNL,Wemoto  give 4.7 for one,and 4.2 for another.


 HELP

--- End quote ---

John.

Very basically, at 6k the engine is firing at say 100times per second. For a typical coil time constant of say 4ms, the coil could reach steady state DC magnetism say 250 times per second, so you can see there is significant time for the coil to “charge” as some folk like to describe it. However, the ability of the coil to achieve ‘steady state’ will be determined to some extent by the timing advancer. Without advance the rpm might well outstrip the time constant/dwell time and hence the ignition break down. I’m convinced it’s an ignition system issue. Though I could be wrong, I normally am. I’m very suspicious of that 6k figure as it definitely resonates with ignition advance, coil and points.

Sesman:
Apologies 125 times per second, not 250 as the coil needs to discharge too…..

Sesman:
Just stumbled  across this looking for typical coil time constants - explains it far better than I do.

https://www.denso-technic.com/bg/everything-you-need-to-know-about-ignition-coil-charge-up.

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