Topic: HELP! again ha.

[1977CBFOURK]

My 1977 CB550K is still haveing some problems with the first cylinder. The pipe on that cylinder is much cooler than the other 3 cylinders. I have cleaned the carbs multiple times now and am almost positive (even though many of you will not agree with me) that they are as clean as they possibly can be. What could be makeing only the first cylinder misfire.

additional information,
On idle seems to back fire alot when the bike is cold, once road around the back fire stops but  it still seems to be missing and the pipe is still MUCH cooler than the rest

Plugs are new and have tried swapping
Air filter is new

[1977CBFOURK]

o yes, and everything is STOCK on the bike

[kslrr]

Have you checked for a spark on #1 and even though all carbs are clean, are you positive that carb #1 is getting fuel?

[1977CBFOURK]

one has very good spark, and im almost positive its getting fuel because it fires, just  misfires alot. also the plug came out tan!!??!!?? but pipe was still warm to touch unlike the other cylinders that would make my hand blister if i touch them

[kslrr]

Tan is good.  Are all plugs similar in color?  If not, that would suggest differences in idle circuit fuel/air mixture.  How does the bike perform above 3/4 throttle?

[1977CBFOURK]

all plugs looked about the same, runs pretty well at 3/4 throttle but still has the poping from exhaust and 1st cylinder stays cooler, not cold, but cooler

[kslrr]

Ok.  So it sounds like #1 is not firing most of the time over all throttle range.  The popping you hear is unburnt fuel in the pipes igniting.

Other things to check for are:
Proper valve clearances set.  Too tight will prevent a valve from closing thus not allowing the fuel charge to compress.
Good compression.  A compression check of all cylinders will tell you the health of your engine.

How many miles are on the bike and has it run well before?

[1977CBFOURK]

14000 on the bike.. I bought the bike from a guy who had it sitting in his garage for ten years or so. after cleaning the carbs it started right up, cleaned and cleaned a few times over now and that is where im at. bike is in very good condition, really no rust, it does have after market 4 to 2 exhaust on it though so not fully stock. I thinnk that they bike has ran on 3 cylinders for a while though because the first pipe is shiny crome and the other 3 have a little color disfigerment and a few light rust dots

[750K2]

hi there!  i suppose one could go back to the basics.  have you checked the valve clearances or synched the carbs?  another item to check is the setting of the air/fuel screw settings.  if you've done all this and it still is causing you problems...aside from visually checking the spark on that cylinder i'd have to defer to the real experts.  good luck!

[TwoTired]

Have the carbs been vacuum synched?

[1977CBFOURK]

just benched synched to factory setting

[TwoTired]

There is no bench sync procedure in the Honda shop manual.  There IS and vacuum sync procedure.

Where did you find factory documentation for "bench sync"?