Topic: Slight misfire at idle???

[tg305]

I have cleaned my carbs on my 78 CB550K a few times of late and continue to get a slight misfire at idle.   Can this be timing related?  I have retimed the bike in the past but the points are kind of old.......   Any thoughts?   thanks   Tim

[750k5]

put a set of points in it....

[TwoTired]

I have cleaned my carbs on my 78 CB550K a few times of late.

Even the slow jets?

Can this be timing related?

It can be

I have retimed the bike in the past but the points are kind of old.

Define old.
Anyway, there are alot of things that can make the engine misfire.   This is why they need periodic tuneups.
You should probably relate the tuneup status of the machine as well as any modifications made to the engine, induction, and exhaust.
How old, what type of spark plugs?
Have you done a carb sync?

[tg305]

sorry   you ask good questions. The bike is unmodified.  I went thru the carbs twice   puled the slow jets and cleaned them out.  Adjusted the valves and tensioner.  I have not synced carbs  but just purchased stix.  The idle wanders a lot which I believe may be out of sync carbs.   By old, the points were in the bike when Ipurchased it two years ago.  They could be as old as 18000 miles.  I did regap them and timed the bike with a timing light.  It runs well  gets mid 40's for mileage.  Starts hard when left for a week or so.  Otherwise it fires up immediately when used daily.   Hope this helps a bit   Thanks for the responses so far....

Tim

[TwoTired]

Without a good carb sync, the engine can be confused as to which is the dominant cylinder.  Meaning it can idle irregularly.

The points normaly pit on one side and make a pointy spire on the opposite contact surface.  This makes accurately setting their gap problematic.  Either new points are used, or a contact file is needed to remove the spire.  If the spire builds rapidly between tune-up intervals, then new condensers are indicated.  I dress the points each tune-up.  About ten dressings is the limit, if you keep the point cam well lubed so the rubbing block doesn't wear down too rapidly.

Starts hard when left for a week or so.  Otherwise it fires up immediately when used daily.

This is typical for all the Cb550s I have.

Misfires can also be caused by the plugs carbon fouling the center electrode insulator from a a too rich mixture.  This can be instigated by a dirty air filter.  Both these are addressed during a complete tune-up.

Cheers,

[bryanj]

Any Honda from 77 on, if left for more than 2 days will need the carbs drained out so "fresh" gas can get in.
seems to be a mix of Honda leaning them out to reach emmission regs and gas getting crapper

[tg305]

thanks for the input guys.  I'll replace the points/condensors   and sync the carbs.............    Tim