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'80 GS550 Carb Problems

  • Thread starter Thread starter baseballisgodCSU
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baseballisgodCSU

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I have a 1980 GS550 that is in good shape, and was running when I bought it. But it wasn't running perfectly so I thought it'd be a good idea to clean and rebuild the carbs. A carb rebuilt kit, new o-rings kit, and a months worth of work and it's still not running. Yesterday I got it running on all four cylinders but it wasn't idling well because of how rich it was running. It wasn't running before because I hadn't backed out the pilot screws, but the 1 1/2 turns I did had it running too rich. So based on what I read in this and other forums, I thought backing out the pilot screw 2 turns would solve the problem...Unfortunately it didn't, at this point I'm open to any suggestions whatsoever (the weather is way too nice for my bike to be stuck in the garage).

Thanks,
Pat
 
Does the bike have any modifications? Is the electrical system charging well? Is the valve timing good? You may have to check some other things than the carbs.
 
I recently rebuilt my carbs with non-OEM carb rebuild kits and new o-rings. After reassembly my bike ran like crap. A lot of members here highly recommend re-using your original jets if they are in decent condition. I went back to my original jets and things were back to normal, but this being my very first experience working on carbs, the second time that I went through them to re-install the original jets I found some mistakes I had made in re-building the needle jets as well as a couple other mistakes such as float height etc..

My advice would be to go back through the carbs and re-install your original jets. Check your float heights very carefully, and verify that everything is assembled correctly by checking it against a parts breakdown or the pictures in the "GSR Garage".

Make sure you do a good "bench sync" before installing the carbs back on the bike. I did mine by following the advice of other members using a twist tie from a loaf of bread as a feeler gage. You can search for this procedure here in the forums.

Make sure the carb vent lines coming from the vent tees between the carbs are clear and not kinked. (I just leave mine removed.)

If you have a stock air filter, remove it and clean the filter element as per your manual.

Finally, make absolutely sure that your carb and jet specs match the specs below if you don't have any major modifications. Good Luck.

Originally posted by First Timer HERE:
GS550 (80-82) the specs are for the CV's

idle r/min 1100-+/-100r/min
carb mik bs32ss (4 separate carbs)
id no 47160 (us) 47170 (can)
bore size 32 (1.26)
float height 22.4.+/-1.0 (0.88 +/-0.04)
fuel level 5.0+/-0.5 (0.20 +/-0.04)
main jet #92.5
main air jet 1.6
jet needle (4bel2 us model) (5f42-3rd notch Canadian adjustable needle)
needle jet x-6
pilot jet #40
throttle valve #135
by pass (0.9, 0.7, 0.7 us model) (1.0,0.8,0.8 Canadian)
pilot outlet 0.7
valve seat 2.0
starter jet #35
pilot screw 3.5 turns back (mixture screw)
pilot air jet (us model #150) (#120 Canadian)

these setting apply to all 550 models with the CV style carbs,
Me personally would try to get the carbs as close to the the Canadian specs as possible the US models were lean out so much to meet emissions. the Canadian specs give the bike a hardier fuel supply.
 
Thanks for all the help guys, I think all the suggestions are definitely going to help, and I used the old parts for most part. One more question though, where should the pilot jet be set? (I've heard anywhere from 3 turns to 1 1/2 to all the way tight.

Pat
 
The Pilot JET, which is underneath the rubber plug inside the carb bowl area should be screwed all the way in.

But I think that you are talking about The Pilot Screw, (Mixture Screw) which is located on the front external part of the carbs. I started with the setting recommended in the information above (3.5 turns out from seated) and it worked fine for me. I've been riding my bike for a couple months using this setting with only a bench sync and everything is fine except for fuel consumption. I will be fine tuning this weekend with a pilot screw adjustment and a vacuum sync on the carbs.

After you get the pilot screws to a baseline setting and your bike will run and idle on it's own, then go back and adjust each pilot screw in or out for the highest RPM at each carb. Set your idle speed screw to about 1100 RPM and then start adjusting the #3 pilot screw for max RPM. Then continue to adjust each carb while setting the idle speed screw back down to 1100 RPM between tuning each carb. Make sure to write down the amount of turns out (from seated) that you turned each pilot screw for future reference. Good Luck.
 
Is it the same plug all the time. I would rule out coils because they are usually double fire and 2 plugs would go at the same timeThe bike is a 4 cylinder. Speaking for myself, i know nothing about the model. Does it have a vacum operated petcock????
 
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