Topic: Cb500 running on 2-3 cylinders

[TwoTired]

The lever is mounted 90 degrees w.r.t. the butterflies.

Look carefully at the stampings on the choke lever.

Lever down: choke off, butterflies open.
Lever up: choke on, butterflies closed.

[fevah]

Long time no update.

you were dead right about the carbs, i was an idiot.

I put the needle jet back to stock position and took it for a ride with no pods. it idles better (aside from #4 backfiring thru the carb sometimes) has a small flat spot from 4000-5000 ish but it reved out a lot better. Hesitates a bit but generally better than before. pulled the plugs when i got back from ride and:

#1 - black, little wet - so rich ?
#2 - brown - all good ?
#3 - brown - all good ?
#4 - white - lean ?

all the carbs are set the same, main jets are 2 sizes larger than stock i think. i forgot to check the idle screw settings. Any ideas on the differences and the cause of the backfire on #4 ?

[TwoTired]

Air filter effects the mixture.  Will run lean without air filter.  And, will wear out faster, with the pistons scraping dirt off the cylinder walls.  Maybe your air is always clean and without dust/dirt?

Last part of the tune up is to check/adjust the carb's vacuum sync, so all the carbs and cylinders are working together.  Weird idle/backfires can be caused by this alone.

Have you verified float height in all carbs?
Are all the orings inside the carbs soft and sealing?
Did you ever check the tappet gaps?
Are you certain that their are no air leaks in the carb couplers?

[fevah]

i just ran it with no pods to see if that helped the issue. i can put them back on and have another go.
i have only bench synced the carbs with a drill bit so i really shud get a friends manometer thing and check it properly.
i reset all the float heights when i 1st stripped the carbs but it probably wouldnt hurt to check them again.
i did check and regap all the tappets.
havent checked the carb couplers for leaks, can that be felt or do i need to spray something around and listen for change in idle ?

[rogue6]

It doesn't seem like anyone has suggested you might have an issue with the coils themselves.  One fires cylinders 2/3 and one fires cylinders 1/4.  Your symptoms combined with that fact create a coincidence too large to ignore.  Swap out the coils between each side and see if the problem follows to the different cylinders.

[fevah]

i forgot to add that ive put in some cb750 coils and it is now running on 4 cyl after 1 or 2 new plugs as well