So I inherited this pretty badly neglected CB550K from a close family friend who had one too few spots in the garage. It had been sitting outside for at least two years, had some gremlins to clear out, was filthy, had several busted or missing panels or components, and after about a month of wrenching, I had it running perfectly.
Or so I thought.
I'd spent a long time buttoning everything up and testing it out to be sure it would be fine for longer rides, but the first time I rode it to work, the trouble started.
The trip out was wonderful. It ran like a Swiss watch, sounded great, pulled great from any speed, and was clean as could be.
But on lunch it started to get a little bit of breakup, like it was running a little lean. Then when I went to ride it home, the real trouble started. Right off the bat it was having trouble. You could accelerate hard for a split second, or accelerate gently for a few seconds, and it would very suddenly begin to break up, backfire, and run really short on power, lose speed. Distinct difference in engine tone, not quite sure if it was 8-stroking or what, as I'm unfamiliar with the sound. I stopped for a few minutes to have a look, found nothing obvious wrong, and it ran nigh on perfectly for the next 15 minutes, at which point it went back to the same situation. I was able to limp it home at about 45mph and pull over every few minutes to let the line of cars behind me go by whenever they were willing not to just pass anyway and try to run my ass off the road.
So I ran through the gamut of fixes, starting with seafoam at high concentrations, the Italian tune up, double checking my timing, double checking my sync, reading plugs (Slightly on the rich side at idle, perfectly clean and light tan after running under the error condition for 20 seconds and chopping the ignition), cleaning tank, replacing tank filter screen, cleaning carbs, completely rebuilding carbs after cleaning didn't work, drilling out the vent on the factory gas cap, and replacing the gas cap.
The issue persists and I am at wit's end. I nursed this thing back from the brink only to have it have an aneurysm on me the very same day I decide I'm satisfied with it. It was running better than fine for the better part of a month up until this issue reared its ugly head. I have no idea where else to look.
I do not have inline fuel filters, the bike has the stock airbox, and I do have a Delkevic 4-into-1 exhaust with full baffles, but it ran fine like that on stock jetting for weeks before having this problem.
Or so I thought.
I'd spent a long time buttoning everything up and testing it out to be sure it would be fine for longer rides, but the first time I rode it to work, the trouble started.
The trip out was wonderful. It ran like a Swiss watch, sounded great, pulled great from any speed, and was clean as could be.
But on lunch it started to get a little bit of breakup, like it was running a little lean. Then when I went to ride it home, the real trouble started. Right off the bat it was having trouble. You could accelerate hard for a split second, or accelerate gently for a few seconds, and it would very suddenly begin to break up, backfire, and run really short on power, lose speed. Distinct difference in engine tone, not quite sure if it was 8-stroking or what, as I'm unfamiliar with the sound. I stopped for a few minutes to have a look, found nothing obvious wrong, and it ran nigh on perfectly for the next 15 minutes, at which point it went back to the same situation. I was able to limp it home at about 45mph and pull over every few minutes to let the line of cars behind me go by whenever they were willing not to just pass anyway and try to run my ass off the road.
So I ran through the gamut of fixes, starting with seafoam at high concentrations, the Italian tune up, double checking my timing, double checking my sync, reading plugs (Slightly on the rich side at idle, perfectly clean and light tan after running under the error condition for 20 seconds and chopping the ignition), cleaning tank, replacing tank filter screen, cleaning carbs, completely rebuilding carbs after cleaning didn't work, drilling out the vent on the factory gas cap, and replacing the gas cap.
The issue persists and I am at wit's end. I nursed this thing back from the brink only to have it have an aneurysm on me the very same day I decide I'm satisfied with it. It was running better than fine for the better part of a month up until this issue reared its ugly head. I have no idea where else to look.
I do not have inline fuel filters, the bike has the stock airbox, and I do have a Delkevic 4-into-1 exhaust with full baffles, but it ran fine like that on stock jetting for weeks before having this problem.