Topic: bike runs worse when warmed up

[needswork]

Hi all.
'78 CB 550K with 4 into 1 and pods. Still working out minor carburetion issues but lately a more pressing problem has presented itself. Normally, I ride most evenings by myself probably about 10 or 15 miles. But after a while, the bike starts to run worse (best when I first start out), it starts to idle poorly (also a carburetion issue) but most noteable is that it kinda "breaks up" when I get heavy on the throttle.  Someone suggest my coils and reading the FAQs here I'm kinda suspicious about the plug wires. I changed the plugs less than 100 miles ago. Am I right to be trhinking about te ignition system (coils/plug wires) ?

[Jay B]

If it is carbs, it is probably running rich if it runs worse as it warms up. To check wires get it warmed up some evening and look for jumping sparks in the dark.

[Gordon]

What do the plugs look like?

[jsaab2748]

What do the plugs look like?

I'd start there too

[OldSchool_IsCool]

Needs,

I'm wrestling with poor running problems when hot also.  I've been running two threads lately:

http://www.sohc4.us/forums/index.php?topic=11928.0

http://www.sohc4.us/forums/index.php?topic=12075.0

At this point, I've tracked it down to wrong spark plugs and corrosion (patina) where the plug caps jam into the plug wires.  Can't say this will fix your problem (or mine, for that matter!) but they are easy checks to make.

[needswork]

I went out for a smoke and started looking at the plug wires and pulled the caps. The spark plug cap on #3 was really loose (as in barely on). I then tightened them all up and went for a ride. Still doesn't idle well (carburetion issue i'm sure) but it didn't break up when I was heavy on the throttle after it reached operating temperature. All better 
Thanks everybody- you guys are awesome! Next, larger pilot jets.