D@#*@*n It - Now what....

[Anonymous]

1981 GS550T - was running rough, but on all 4 cylinders, so I
pulled and cleaned the carbs - replaced them, now bike was running on 2 cylinders. (3 and 4 pipes hot, 1 and 2 not. Could pull the plug wires on 1 and 2 bike would run, pull the plugs on 3 or 4 bike would die.) :? Removed, recleaned, replaced carbs. Bike is now running on 3 cylinders. (1, 3 and 4 running hot. Same deal with pulling plugs as above, but bike will run if I pull #2 plug wire, but will die if I pull the other 3.) I did get a small shock pulling the boot on #2, but only once - spark still good)
Have spark at all 4 plugs. Trimed back the spark plug wires, reseated the boots, get good spark. Coils good. Before I pull the engine and delve into the inner workings, 8O like looking at pistons, valves and the like, was wondering if there was any ideas of what might be causing this. I am going to pull the carb on #2 (the nonrunner) and reclean, rebuild it agian.

Any ideas?

[Anonymous]

#2 is the carb with the petcock, is that your problem?

[Anonymous]

Yes - I also checked the petcock, and it is functioning correctly, fuel flows properly. What are your ideas about it?

[Anonymous]

Sorry, I don't have any idea what is wrong with your bike. I was just making sure that you thought about the petcock since you are seeing red. Perhaps there is a vacuum line problem. How about switching the carbs order, is that possible? I've never tried. Setting your valves and doing a compression check isn't too difficult and you're probably due for both anyway. You could try swapping the coils around as well since that is also easy to do too. Just don't give up.

Good luck, Steve

[Anonymous]

Sorry - not really seeing red, bought the bike as a project, and it is living up to it's job. :twisted: Would valve clearance, as mesured from under the cam cover, cause a clyinder not to fire? Besides, I am getting REAl good at removing, cleaning and replacing carbs.. ...mainly thanks to the great info found on this site....

Never really thought about switching carbs..I'm not sure it could be done with the throttle set up..but it might be worth a look..

Thanks

[Anonymous]

Get the carbs sychronized, and then see if that fixes it. Anytime you remove the carbs you gotta get them synched

[Anonymous]

Is the vacuum line connected to the right carb? I've had a similar problem with my 78 GS550. The previous owner had connected the vacuum line to the wrong carb. I cleaned the carbs, and hooked up everything the same way. Wouldn't run on all cylinders. I remembered a post here, that the vacuum line on slide carbs should be connected to carb #3, on CV's to carb #2. I have slide carbs, and the vacuum line was connected to carb #2. I put the vacuum line on to the right carb, and the problem was solved.

[Anonymous]

have you removed the vacume line to see if it has any gas in it-

[SqDancerLynn1]

the carbs can be very tempermental, I think you will need to clean the offending one again

[Anonymous]

I really don’t think that you need to rip the engine apart.
What colour are the plugs when you take them out. Are they wet, dry, black or white or unchanged. This could tell you a lot. When assembling the carbs did you synchronize them visually? This should be good enough to get the bike running on all cylinders. Once running then fine-tune it.
Are you running fresh gas?

Sounds like your ignition system is OK. If you have a spark it should be OK. Unless the timing is way off but it ran on all four before you took the carbs apart. Which leads me to believe that it must be the carburetion.

Fill us in as you go along with your work.

Roman.

[Carter Turk]

550t

Float height on 1 & 2. Float damage/cracked. Intake boots cracked on the inside/sucking air. Correct plugs. Float needle assembly worn on 1 & 2/ look for dents or rings around seating area of needle. Good Luck Carter

[argonsagas]

All good advice above.


Seems unlikely there is an internal problem, but a compression check will tell you if the cylinders are OK, and it's easy to do. (Remove all 4 plugs and do the check with the throttle OPEN)

Since it was running on all four before the carb work, it seems likely that is where your problems lie.

Check the vacuum line position, as Jojo suggested, and the carb boots.If all look OK, then pull your carbs again and set them up visually, BUT
before trying to adjust anything, loosen E V E R Y adjuster including the idle setting.

This may seem unnecessary, but the opposite is true, especially for cylinder 2.

A couple of additional points.

It takes almost nothing to block the carbs up. I found a spray-can carb cleaner with a nozzle extension to be essential.

Double-check the idle jet in your #2 carb. Remove the base and take out the jet, then try to see through it. If it is blocked, you can stick a single bristle from a wire brush in a cork or pencil to carefully clear it, and after that you MUST blow it from the top, using the long nozzle of the spray carb cleaner, to ensure the grit is gone.

If you don't already have one, instal an in-line gas filter. Do it right away.