Just for Starters !

[Bryanj]

Plugs, Plug Caps and vacuum balance of carbs---AFTER all service items done. Coil  can't fail to just one plug as it's double ended but one lead can short to frame etc.

[veefour]

Well i have done all i can think of, new plug caps et all ( all plugs have strong spark ). Balanced Carbs again ! At second thoughts it feels more like the choke is staying slightly on, when ridden it is sluggish but when opened up above 5000 rpm it accelorates quite quickly. Where do i look now !!

[K2-K6]

It seems like you've been through all the logical stuf that should be checked and set, so if you're happy that those items are ok then you may having to start looking a bit further.

Next i'd check that you have no valve clearances that are too tight......followed by a compression check if you haven't already done that.

Just a quick check item to give you a lead.....start it from cold and run for about 10seconds then switch off......now carefully check the down pipes close to the head to see if you have any which are cold to indicate which cylinder could be giving you that missfire feeling.

[mickwinf]

see my old post  "3 cyl 550"  as i had similar probs, turned out to be a bent float needle!

[veefour]

Next i'd check that you have no valve clearances that are too tight......followed by a compression check if you haven't already done that.

Just a quick check item to give you a lead.....start it from cold and run for about 10seconds then switch off......now carefully check the down pipes close to the head to see if you have any which are cold to indicate which cylinder could be giving you that missfire feeling.

I had previously checked valve clearances, & all the downpipes are getting hot. Will try a compression test next.

see my old post  "3 cyl 550"  as i had similar probs, turned out to be a bent float needle!

All the jets & needles etc. are new, & i have set the float levels as well.
The only thing i have not checked yet is the ignition timing !! Although i have a nagging feeling it is still carburation related.

[veefour]

Braving the cold yesterday ( looks like we are going to put up with it for a while longer !! ) i decided to take the carbs off & check them all out again. After studying the manual ( again ) it states the needle clips should be in the 3rd / middle groove, now for some reason the original ones were in the 2nd groove ( from the top ) so this is how i had set the new ones. Would this have any effect on the poor running !

[veefour]

Well I still haven't got to the bottom of the problem. The bike starts on the button, it does need a bit of fiddling with the choke for a minute or so but then idles nicely at about 1200rpm. While stationary it revs cleanly & responsively. The thing is when riding it feels rather sluggish with a burbling misfire sound, but when opened up quickly & the revs reach about 5000 it takes off smoothly & surprisingly fast. Took it for a 30 mile run this morning & apart from this it runs well. Getting a bit peeved now, any more ideas on this please.

[veefour]

I have just noticed the Choke Flap on the Carb nearest the Choke Lever is not opening quite as much as the others. It's only slightly different but do they all have to line up by the same amount.

[K2-K6]

If as you describe it's only slightly different, then it would be unlikely to have such a pronounced effect on overall running.....it would be more typical having one odd setting to notice less peak power I feel.

If you haven't verfied the timing is accurate and the advance is working correctly, then it would be wise to check it through to mke sure nothing fundamental is wrong.

Presumably once it's warm it will run without choke at all? and if so, when you are running at sub 5000rpm (hesitantly) then if you hold the throttle steady and bring some choke in, then does it improve or get worse?

[veefour]

I am beginning to think I am never going to get to the bottom of this  I have just changed the coils for some different ones now & this persistent misfire is still there. So to recap, coils changed, new plugs & caps, points (timing done), valve clearances done, all new carb jets, floats height set, carbs balanced, compression test done all the same pressure. Engine starts on the button & revs cleanly with no smoke & all four pipes get hot, but on accelerating there is this persistent misfire. The No.1 cylinder plug is getting very sooted up so somehow it must be running rich but why !! (Not the plug as I have swapped them around). Before long it will be staying under the covers if I can't sort it soon  !!!!!!!!!!!   

[z1100r]

Go up a long steep hill and let it pull in top gear wide open throttle for a while, plug chop it and check out the sooty plug. If its feels to be on all 4 flat out and plug has cleaned up..get the carbs off again and check that particular one out. I suspect an issue with that carb. For these little Hondas to run like sewing machines the carbs have to be perfectly clean, set up correctly, and balanced. I have had a simlar issue with blocked primaries. Hold them up to a light and look through them, you should see a pin prick of light. On the later better carbs you have to pull primaries out with pliers. buy a set of cheap micro drills off of Ebay...they are great for poking out any crap. If you use your fingers to twiddle them you wont do any damage. Fairly convinced its the carbs. 

[veefour]

Does anyone know where I can get carb manifold O-rings if I need them, David Silver doesn't list them.

[Bryanj]

Same ones in the tappet caps

[veefour]

Same ones in the tappet caps

Well done that man. Cheers  .

[bomber]

Soounds to me like you need the proper Honda manual for the adjustments, as to the standpipe officially you have to replace the complete floatbowl which i think is teh same as the 500 but the only parts book i don't have is the 550f so i cannot be 100% on that.

Does this help:  http://www.dotheton.com/downloads/CB550_Parts.pdf

Thank you so much for this link!
I have been looking for this for ages...