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550T Won't run

  • Thread starter Thread starter mbautsch
  • Start date Start date
M

mbautsch

Guest
I acquired a 550T a couple of weeks ago that had been sitting for couple of years. After changing the oil and replacing the plugs I tried to start it. It wanted to run but fuel was pouring out of the carbs. I pulled the carbs and ordered 4 rebuild kits. After pulling them apart the problem was obvious, the needle valve was so gummed up that I couldn't pull them out of their seats without pliers. I replaced the needle valves and seats and all of the o-rings after a good cleaning. I've reassembled everything, I'm sure that I have the fuel and vacuum line in the correct locations. I backed the air screws out 3.5 turns. I'm getting nothing when I try to turn it over, it's not even trying to fire. I've tested the plug wires and am getting plenty of spark. I've moved the air screws in and out to several different positions and get the same results. I have the fuel tank on about 3 feet of hose extension and set aside and above the bike so that I can make adjustments.

I would appreciate any suggestions.

Thanks
 
Did you take the carbs apart? Sounds like you need to bench sync. This means you need to adjust the idle throttle stop knob and make sure all the throttles are about the same throttle at idle. Try doing that with full choke and it should fire up. If not you need to figure out if fuel is getting into the carbs (check bowls) and then into the cylinders (spark plugs wet?). If all this looks good then check spark. Also, check valve clearance. It seems some starting issues can be caused by too little valve clearance. Also make sure your battery is charged up.
 
Thanks for the info. Would not doing a bench sync make it act this way? Unfortunately I did not do the bench sync, learning the hard way. I will take them out and do the bench sync tomorrow and see if that does the trick.
 
Sync will not cause the issue described. Also, set the air screws to 2 turns out and don't touch them again until the bike is running properly (they won't cause the problem either).

For some reason it sounds like the engine is not getting any gas. Set the petcock to the prime position and confirm that gas flows with the fuel line off. Assuming it does, hook it up and let the float bowls fill. If your needles are sealing properly there will not be any overflow like before. You can loosen the carb float bowl drain screws and confirm there is gas in the float bowls. After you confirm there is fuel where it belongs, hit the starter with full choke and it should light. Of course, this assumes that all the jet passages are clear, including the killer small orifice in the pilot circuit (you did clean them when you took the carbs apart right?). If not, your next task is clear...
 
Sounds like fuel to me.

Have you checked to see if you have fuel in the float bowls?

Pull the plugs out and see if they are dry or wet.

It's likely that the carbs will have to come out again and have to be cleaned so all the pilot jets etc are clear.

Suzuki mad
1981 GS1000ET
1983 GS(X)1100ESD
2002 GSF1200 K1
 
Have you verified compression?
When I had a blown head gasket the compression was so low on two of the cylinders that the bike would be nearly impossible to start (20 minutes of cranking MIGHT get her started - of course I'd be jumping off may car battery because the bike's battery was dead by then).
Of course, if I'd known then what I know now, then I would have simply checked compression and discovered the blown head gasket a lot sooner.
 
Looks like I've got fuel coming out of the tank but it's not getting to the engine. The bowls are full but the plugs are dry. I did a pretty thorough cleaning on each of the carbs while following the directions on this site. I'm wondering if some debris from the tank could have broken loose into the rebuilt carbs. When I got the bike I drained the tank and put fresh fuel in it, but I did not make any effort to clean the tank and I'm wondering now if that was where I went wrong.

Thanks
 
Sounds like fuel/carbs.
Pull the carbs, disassemble, clean everything, be carefull, do one at a time.

Take your time, she'll start.

Edit.
Pull the tank and inspect. If it looks ok install a small inline filter. if crappy, get the gunk out!
 
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Be careful when buying an inline filter. Some are made to work with gravity-fed fuel systems, others are not. Try to find a filter made to work with a lawn mower or other small engine that does not have a fuel pump.

It would also be worth your time to check the petcock. First, remove your 3-foot hose from the carbs and place the end in a catch can. Move the petcock to PRIME to see if fuel flows. If it flows, that shows that the in-tank filter is at least flowing some fuel. Move the petcock back to ON, apply some vacuum to the small vacuum inlet on the petcock. Don't suck on this, use a pump. If the diaphragm is bad, you could get a mouthful of gas. :shock: If you get fuel flow, the problem will be in the carbs. If not, repair or replace your petcock first.

Remove the carbs, open them up, remove the inlet needle valve. There should be a screen on top, which is your last-resort fuel filter. Clean them well with carb cleaner and a toothbrush, blow them out with compressed air. If you have cleaned a bunch of gunk here, there is a chance that it will be OK, but, since you have the carbs out anyway, go ahead and blow some air and carb cleaner through all the little passages to make sure they are open. Just be sure to keep your safety glasses on, as some of those passages may be pointing back at YOU when you blow through them.

It's not terribly hard, just takes some time and attention to details.


.
 
Blow on each carb overflow hose and the try to start. Don't know why it works but ...

After my 550T sits over the winter it is hard to start, if I blow on the hoses after setting the petcock on prime for a minute or so it starts immediately.

Bob Uehlein
1981 GS550T and 1975 CB550
 
Do you have your vacuum line connected to the petcock and the engine? Some petcocks require a vacuum to flow gas even in the prime position.
 
Yes I do have the vacuum line connected. When bike is used regularly the petcock works fine.

On my 1975 Honda CB550 which has a conventional manual petcock this trick also works. Normally after sitting all winter it would take 6 or 7 5 second cranks with electric starter to fire up. If I blow on the overflow lines it fires up immediately.

Years ago I had a snowmobile with a primer bulb on a hose connected to the carbs. Maybe this is the same theory. The bulb was not connected to the fuel line.

Bob Uehlein
GS550 & CB550
 
IT'S ALIVE!!!! I took the carbs back off and complete cleaned them again. Put them back on and it's running great. Still needs a little tuning but it's on track to be on the road this week.

Thanks for all the help.
 
Good deal. Now make sure your tank is clean and free of rust or you will be right back where you started.
 
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make sure you use a thin wire to clear all three pilot passages just above throttle plate in venturi..if these are plugged bike won't start. air mix screw is one of these holes...rob
 
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