About meHello all, I am a new rider who just picked up a 77 cb550. I am about to finish up my degree in Raleigh and move to Mobile soon after. I have some experience tinkering around. I have a 67 F-100 I grew up helping work on and taking over as it became mine, and a beater civic to save on gas. Though I would by no means call myself a mechanic. Being proficient to that level comes with shop time I just don't have under my belt yet.
About the bikeA 77 cb550k3 with the PD carbs. Previous two owners' project. It has some issues and I have been working to get it running right. It came to me with no cluster, pods, and 4 into 1s. There was some work done before winter, a carb clean and new plugs/coils. Seller sold it to me running but not nearly well enough to ride. Bike was "bogging down over 1/3 throttle" but was not reliably starting or idling.
Initial thoughtsThought the bike needed to be rejetted. Likely cause of some issues for sure. Bike was running 92.5 mains (and a single 95) and stock ilde with pods and straight pipe 4 into 1s. So, of course I try the easy way out first and rejet. Upon doing more research as the jets were coming in I realized I might have some work cut out for me.
Weekend 1I pull the tank and drop the carbs, replace leaking petcock, open up bottom end of carbs and rejet, the bowls looked pretty good but the idle jets had some white residue. Went from the 92.5/95 mains and stock idle to 120 main and 45 idle. (I figured the 120s would be rich but the bike would run.) Got the bike to turn over and idle, the second time I started up after rejetting the bike was only running on 2 and 3. Maybe I did not have enough gas. Rain came and exams were looming.
Weekend 2I try to crank it up and same story 2,3 hot with 1,4 cold. I put all 1.25 liters of gas I have in the tank now that the petcock is not leaking. No improvement, though this time it feels like 3 and 4 are hot while 1 and 2 are cold. Having read that coils are 1&4, 2&3 the previous observation makes me think its not them. The coil packs were replaced in 10/22 anyway when tank was off they looked pretty good though I did not test anything with ignition system. At this point I let the bike sit until cold again, crank it up and what do you know all 4 are getting warm, no super long rev hang, smooth throttle response and only slamming to WOT would cause any upset. So I take it for a spin. The bike did not like any throttle and would only get going under the slightest twist. If I went anywhere near 1/4 or past the bike would sputter and sound as if it were sucking air. Under any throttle the bike was not happy, but I could massage the revs up and stay just under the sputtering. I cant say for sure what was going on during the ride but it did not feel like everything was firing, even with the sputtering. Checking the pipes 7-10 minutes into riding and 1 was cool to the touch while the rest were nice and hot. Around 15 minutes of riding and I'm heading back when the bike really craps out. This felt like only two cylinders and now not only was there sputtering but the bike wanted to die with too much throttle.
Let the bike cool down again, start it up and feels fine, let it idle to check pipes. All are warm so I take it for another spin. Still sputtering but this time I try to power through it, as I get to the higher throttle positions the bike just keeps fighting to go, jerking when it does fire right and sputtering/missing otherwise. I take it to some hills and go down just to get some speed. This helps the sputtering but only pushes it further up the throttle response. If I let go of throttle at speed I get some burbles and backfires.
Well, that is a pretty complete chronology of the bike and I for the past month. I have a video of the first test ride, and a video I found on youtube that does seem very similar.
If any of you have any thoughts on the issues or general guidance I am all ears. I don't have much access to the bike (in a buddies garage). I will get a few more sets of jets to play with, and some plugs. But the intermittent firing (or whatever is imitating it) issue i think will persist. Upon some more research I know that valves and timing should be done first, and that my issue might be condensers. I will look into gathering the tools and allocating the time to dive into that.
But who knows maybe a CB wizard will know the exact issue and solution.
I once had a forum member pull up years worth sale records across multiple sites, of a 50 year old part that was only manufactured for 3 months.
Edit:
here is the comparable riding video. I still need to pull mine off the gopro.
