Topic: Same problem with carb or cylinder over and over and over again. 75 cb550 four

[KevinD]

So, I have had this 75 cb550 four for a year now.  Love the bike love the ride and couldn't be happier but what the !%$@#%!$@# with the carbs!!!  When I bought the bike it had just had it's carbs cleaned 350.00.  I brought the bike home and not being a mechanic or knowing how to rebuild carbs I was not aware that not riding weekly would damaged the carbs with the current gas available.  I did not ride the bike the first month due to license registration a few mods and what not.  When I finally got every thing ready to roll I realized that the number two cylinder or the second cylinder from the rear brake side of the engine was not firing due to the header not heating on that cylinder I took it to have the carbs cleaned again 250.00 this time (The mechanic bought a kit and switched all the internals).  Well since I had that done I have been riding every weekend since except this last weekend, due to the flu.  Bike week is happening this next weekend and I went to do a check on the bike and once again the same cylinder is not heating up when idling at start.  I am going to take the bike out this weekend and see if I have a power fluctuation again but just wondering if owning these means I will HAVE to rebuild the carbs every six months.  I have been using seafoam off and on to try to keep the carbs in check the tank is clean and I have a two fuel filters in line.  Any ideas other than just sucking it up and learning how to rebuild and tune the carbs twice a year? Oh yeah I have switched the plugs and that is all so maybe something with the plug wires? 

Thanks for any and all advice.

[Frostyboy]

Carbs don't normally require such regular attention except if tank is contaminated. By the sound of things that's not likely the case.  The cylinders are numbered from the left when sitting on the bike 1 2 3 4, so we're talking about #3 in your case.
The first thing I'd be doing is changing the plug cap from #2 to #3 & see if the misfire changes with the plug cap. We can talk about using a multimeter later to do some proper testing.
Cheers.

[KevinD]

very cool, yeah I kept being directed back to the carbs but the more I thought about it the more I started thinking its possibly something non related.  I will check the caps tomorrow.  Seriously thanks for breaking my mind free that its only carb related. 

[MickB]

Sounds electrical - not firing. Could be a faulty  plug, faulty plug lead or a coil.

But first pull the plug out and see if it's sparking, if not swap a plug lead from another pot and if the plug sparks, if it does it's a faulty lead.

Anyone else with an idea.

[Kenzo]

Could be as simple as rapping the offending cylinders carb bowls with a screwdriver handle to unstick the float needles allowing the fuel to fill the bowls. Being an intermittent problem seemingly solved by carb rebuilds it dose not sound like electrical.

Honestly you need to commit to learning, understanding and doing basic maintenance repairs. Or you can continue to throw $100 bills at the bike until totally frustrated and selling it.

Personally I wouldn't ride a 40 year old bike if I did not know and understand the basics. It's really pretty easy with resources available online, interesting, and at least for me increase the enjoyment of the bike ten fold.

Cheers,
Kenzo

[KevinD]

Will do some digging around and see what I can figure out today.  Just a heads up, if you have to tell someone they are not doing enough on their bike and they need to commit if they want a 40 year old bike save it.  I hear that every $#%@#$ time I reach out on here for help.  It gets old.  Thanks for the informative posts.

[MickB]

Kev these guys have an inexhaustible knowledge bank, ask and listen you'll save yourself a bundle.

Also look in tips and tricks for answers.

[KevinD]

I do appreciate all the knowledge available on this site.  I have found some great help.  I did the ol tap on the carb bowl and it has been running fine since.  I am planning on a four day trip on the bike and will be going from Phoenix altitude of 1,086 and maxing out at 4327.  I am wondering if I am going to have to worry about the carbs at that difference in altitude. 

Thanks,

[KevinD]

That is great news.  Thanks for the info. 

[cameron]

.  I hear that every $#%@#$ time I reach out on here for help. 

Ha. You hear it a lot cuz its so true!

I Live in AZ, too. and I had a noticeable change in performance last time I rode up to Flag- but never any problems at only 4000 feet. And as mentioned, it was nothing that running her a little hot once I got back down didn't cure. If you go higher, just anticipate not really having the same power you are used to. Its like if you left your choke on a little bit.

[cameron]

Also- back to the OP

I have almost the same bike, and I live in the same climate, and I dont have any problems with my carbs. I haven't had to tune them in years.
So Have hope! Your carbs are probably fine, other than sticky floats.
You can pull the bowls off without removing the things if you wanted to confirm.