Topic: Brief Introduction, and my problem with my 1975 CB550K FIXED!

[HeavensSatans]

Greetings all, I finally was accepted to this fourm My name is Aaron, I purchased  a 1975 CB550K About a month and a half ago, got it together and running from some of the info here during the workings on my Bike, and now time has come to ask a question.

     I recently had the carbs rebuilt, cleaned, new plugs, new inline fuel filters, cleaned gas tank, synched, timed, and cleaned the points. I rode for 627 miles with no problems. One day as I was heading to work, something happened and now the bike is acting very strange. It backfires and will not get past 4rpms while in gear and running without backfiring and jerking. Most of the work on the carbs and what not was after this trying to trouleshoot the problem. I am now scratching my head at what to do ......has anyone else had this problem with their bike? And if so what do I do?

     If you need more info I will be happy to give, post pics, and add video if needed. This bike is my only way of getting around and having a gimp bike right now is not fun!

[HeavensSatans]

I should also add that going up hills makes it very bogged down, and I can't get it over 40mph on flat ground...:/

[SohcCBs]

I'd check the points again, see if they're burning or moving.  Condensers, and terminal connectors.

[TwoTired]

First check the head pipes for even heat.  A cold cylinder focuses your scrutiny.
Never hurts to review the 3K tune-up routine.

Look at the spark plug tips for deposits and describe them.  Or compare to:
http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html
Any deposit pattern different from the others helps point the way toward correcting the problem.

Then lay them on the engine block and see them spark.

[HeavensSatans]

Points are moving and sparking well, the plugs are more or less brand new but I can put a pic of one up that I just pulled from it, pic coming in a few mins. As for the exhaust all seem to be hot, but some are hotter than the others.

[HeavensSatans]

Plugs don't look too bad it seems. I have sanded the points several times with fine grade sandpaper, the advancers are working properly as well.

[SohcCBs]

Points are moving and sparking well, the plugs are more or less brand new but I can put a pic of one up that I just pulled from it, pic coming in a few mins. As for the exhaust all seem to be hot, but some are hotter than the others.

I mean, is the adjustment changing, or pitting from excessive burn.

Checking the exhaust temp or looking at the plugs IS a good way to see what's going on.  Is it all plugs or just one or more.  What color is the spark at the points.

Plugs don't look too bad?  That's saying a lot.  If they're not right, you've got a problem.

Next would be timing.  It can change, too.

[HeavensSatans]

Im trying to upload a pic, but its giving me an error, they are the tan color that is close to best on the diagram. I had it timed as well. The weird thing is the last time I was working on it, it sounded and felt like it was running great, but then when I took it home from my buddys garage is when I noticed the problem was still there.

[Tews19]

Have you checked to make sure all cylinders are firing ? Put a spare spark plug in and exam while running. repeat for all spark plugs. May need to trim the wires from the coils.

[HeavensSatans]

I am going to try the spare plug and check but I am pretty sure all four are firing, here is a pic of the points as well.

[HeavensSatans]

All are firing And I got a few shocks my self testing, lol.

[TwoTired]

Do all the spark plug deposits look the same cylinder to cylinder?

[HeavensSatans]

Aye they do, this ones a real head scratcher.

[SohcCBs]

I think you should verify the point gap and timing, so there's no question there.  It's important to eliminate the possible issues.

[TwoTired]

When you looked at spark, did you verify it arced across the electrodes and not just center to insulator. The white porcelain coated with soot does not insulate.

It may be worth your while to just test it with brand new spark plugs.  Or, borrow some from a known working engine, like I do.

[HeavensSatans]

The point gap was done and I have checked it. Heres a viddy of it sounding sick :/
http://youtu.be/39N_NRDy-tQ

[HeavensSatans]

When you looked at spark, did you verify it arced across the electrodes and not just center to insulator. The white porcelain coated with soot does not insulate.

Aye it arced across.

[Tews19]

Man, that is a tough one.. Sounds like a pretty bad hole in the exhaust??? SOunds dumb, have you checked to make sure the fuel lines are clear? Is the clanking noise coming from the engine? You stated the tank has been cleaned.. Any gunk show up since cleaning???


 What condition is the chain and sprockets? It will give you a missing feeling if worn.. But the engine sounds pretty bad to be honest....
You adjust the cam tensioner?

[SohcCBs]

The point gap was done and I have checked it. Heres a viddy of it sounding sick :/
http://youtu.be/39N_NRDy-tQ

Ya, it sounds pretty bad.  I'd look at the condensors and loose connetors, but sometimes you have to do it all, (adjusting the carb sync, points, timing or looking thru the carbs) over again to find the problem.......otherwise it's just a guessing game.  I adjusted the valves on mine every morning at 6am for 30 days to find the best setting where they didn't move.

[HeavensSatans]

Man, that is a tough one.. Sounds like a pretty bad hole in the exhaust??? SOunds dumb, have you checked to make sure the fuel likes are clear? Is the clanking noise coming from the engine? You stated the tank has been cleaned.. Any gunk show up since cleaning???

You adjust the cam tensioner?

There isn't a hole in the exhaust but the right side pipes are no longer linked together at the ass end from when I dumped it when I first got it.

        Fuel lines are clear, new inline filters too, no gunk showing up as far as I know but I am tempted to drain the bowls just to check.
And no I have not adjusted the cam tensioner. Should I ?

[HeavensSatans]

The point gap was done and I have checked it. Heres a viddy of it sounding sick :/
http://youtu.be/39N_NRDy-tQ

Ya, it sounds pretty bad.  I'd look at the condensors and loose connetors, but sometimes you have to do it all, (adjusting the carb sync, points, timing or looking thru the carbs) over again to find the problem.......otherwise it's just a guessing game.  I adjusted the valves on mine every morning at 6am for 30 days to find the best setting where they didn't move.

Im tempted to get a new points/condenser, its been talked about with my buddy Keith. He helped me get it running again when this first happened. And thats the really weird part. After it warms up a bit I can drive her, but again shes jerky, no power, can't get above 4rpms, but I can get around town if need be.

[TwoTired]

You sure a main jet didn't fall out in one or more carbs?  Do you still have the leaf springs to hold them in?

Take off the tappet inspection caps, check for proper tappet clearance, and if all the valves move to full travel.

Are the pipes at even heat at 3000 RPM?  Check exhaust pressure pulses for each cylinder.

[HeavensSatans]

You sure a main jet didn't fall out in one or more carbs?  Do you still have the leaf springs to hold them in?

Take off the tappet inspection caps, check for proper tappet clearance, and if all the valves move to full travel.

Are the pipes at even heat at 3000 RPM?  Check exhaust pressure pulses for each cylinder.

I know for a fact one of the leaf springs (it looks like a bracket right?) wasn't on there when I bought it. I know the carb its on and may have to check and see if it fell out, but if thats a fact how did I ride 600 or so miles with no problem before this?

[DustyRags]

I built a new exhaust crossover out of a beer can and a hose clamp. It ain't pretty, but it was cheap and works. Cut a circle out of a beer can (or soda if you don't drink), so you have a solid round strip. Flatten one side and slip it between the crossovers so you've got the circle around it. Pinch it together and fold the excess around, and then put a hose clamp in it. Voila! Crossover. Details: http://forums.sohc4.net/index.php?topic=110973.msg1269654#msg1269654

[ekpent]

As for the heat on the pipes test TT is talking about a wet rag should have a good sizzle to it when touched on the headpipe.Anything less can point to a problem.