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Cylinder One not firing at idle

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Xbikerd

Cylinder One not firing at idle

Hey guys.

I have a 76 cb750 k with the 77 78 kein PD carbs I have noticed this problem before but did not pay much attention because it will warm up to match the others in time. I have the pamco ignition, brand new coils wires and caps. valves are adjusted correctly, new intake booties and have cleaned the carbs numerous times. it doesn't make a difference if the choke is on or not if its at idle it is not firing. I checked the plug after letting it idle for a little and it seems to match the color of the other plugs just fine. as soon as i even lay my hand on the throttle it will begin to warm up. I checked my fuel screw and cleaned it out as well still no luck. Please help me out it is really bugging me.

Re-run

Re: Cylinder One not firing at idle

Administrator

Swap the plug and wire with the #4 wire and plug. They fire at the same time. If the problem moves, then it is ignition related and we can look into those issues. If it does not move, then it is carb related.

The ride IS the adventure. The destination is just to get gas!

TOOLS1

Re: Cylinder One not firing at idle

Administrator

In reply to this post by Xbikerd

Last fall I swapped the carbs on the Toolmatic for a set of 78 F-3 carbs, and have the same problem with #4. I did swap the plug wire, and the plugs as Re-Run has suggested, but it is still doing it. Since it has been too cold to ride, and I am swamped with other bikes to work on, I have been procrastinating on working on it. However even though I sonic cleaned the carbs, and drilled the pilot jets out to .45mm, I think the problem is in the pilot circuit. Guess I need to find some ambition, and go figure this out.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

Re-run

Re: Cylinder One not firing at idle

Administrator

Idle issues can be a real pain. Main jet issues seldom cause any really problem, but those damn idle jets...

The ride IS the adventure. The destination is just to get gas!

Xbikerd

Re: Cylinder One not firing at idle

In reply to this post by TOOLS1

Already moved plug wire 4 to 1. no difference. I even went as far as to switch the fuel screw from 4 to 1... no difference. what other parts of the carb should i inspect closely? Thanks for the help

TOOLS1

Re: Cylinder One not firing at idle

Administrator

Pilot jet, and the passages for it.
TOOLS