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[adam77gs550]

Hello all,
I recently purchased my son's 1977 GS 550, this bike is 100% stock, with about 19,000 miles. I started riding in 1967, but this is the first modern bike I've owned(disc brake, electric starter, turn signals)-my other bikes currently are a '67 Triumph TR6R (650 cc) and a '68 BMW R50/2 (500cc). It runs great, I've put on new points/condensors/plugs/plug caps and adjusted the valves. I have 2 questions:
From cold, it starts right up but only if I have the fuel tap initially on "prime" and then switch to "run"-once warmed up, it doesn't seem to matter. Is that the usual procedure?
It's almost ridiculously "cold blooded"-has to idle for a full 5 minutes or so with choke before it can be ridden, then all of a sudden it's like a switch turned and it's as smooth and tractable as you could want all the way to redline. I turned in the pilot air screw 1/2 turn or so to richen it up and that helped some, but it's still a long time to wait to get going-and I'm in a very mild climate. It looks like a real PITA to raise the needle a notch on these VM22 carbs; would there be any sense in going to the next larger pilot jet size? Any help would be appreciated, otherwise it's as nice running a bike as you could want.

Adam

[chef1366]

Welcome!
Check compression!
First thing I would do is adjust the valves and clean out those carbs.

[adam77gs550]

Compression was checked and was in specs, I just adjusted the valves to spec. I'm hesitant to tear apart the carbs unless I have to since it runs so well (other than the problem I mentioned).

Adam

[chef1366]

On the VM carbs ther are seperate air and fuel screws. Maybe if you take out the fuel screw a bit it may richen up the starting process.
I'm a CV guy so I could be off base.

[BassCliff]

Greetings and Salutations!!

Hi Mr. adam77gs550,

You have a bit of a conundrum there. As Mr. chef1366 suggests, carbs need to be surgically clean and valves need to be accurately adjusted (I adjust mine toward the loose end of the spec). Let me give you my world-famous "mega-welcome" and ask you to pay particular attention to the "Top 10 Common Issues", the Stator Papers, and the Carb Rebuild Series. Note that there are both CV and VM clean/rebuild guides available from the homepage of GSR and my website. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

It's good to have you here. Thanks for joining us. Keep us informed.

EDIT: Since it's running so well and the valves are in spec, why not try a healthy dose of Sea Foam?

Thank you for your indulgence,

BassCliff

[feelergaugephil]

I had a GS550 for many years and put 60,000 miles on it! go ahead and clean your carbs out, it's not that hard, you might have some crap in there causing a slight blockage.
Also, in the near future, change those awful points/condensor out for electronic ignition, soooooooo much better than points....
Phil.

[adam77gs550]

BassCliff, thank you, I'll look over your notes-I put some SeaFoam in today, as a matter of fact, and I'll see how that does. As I said, I set the valves to spec(4 of 8 were pretty tight). Chef1366, I can only find a screw for the pilot air mixture (VM22 carb); I don't see one for fuel??
f-g-phil, what electronic ignition did you use on your 550?

Adam

[feelergaugephil]

Piranah electronics, I'm sure there are plenty of other manufactures that make them now.

[Suzuki_Don]

Chef1366, I can only find a screw for the pilot air mixture (VM22 carb); I don't see one for fuel??

Adam the pilot fuel screw is underneath the carb, on the cylinder head side of the carb if that makes sense.

Follow this link.

http://www.thegsresources.com/files/vm_carb_rebuild.pdf

[adam77gs550]

Thanks, Don; what an excellent write up! However, I don't find that screw on my carbs which are model VM22 for the GS550(1977). The write up is for a 750, I believe the carbs are a little bit different. I'm still considering trying a slightly larger pilot jet if running SeaFoam through the carbs and turning in the air mixture screw isn't satisfactory.

Adam

[ned37]

adam, my 1000 has the same problem about not starting unless primed first, but only if it has sat for more than a day. i believe it has a very slight leak in the bowl drain and possibly a plugged vent. the carbs were severely plugged up with dried fuel two po's ago.
if your 550 is a true '77, it should not be that cold natured unless you have partially gummed pilot jets (easy to get). if the date sticker behind the headlite says anything after 12/77 as a manufacture date, you would have epa carbs, which ran lean from the factory and will have a brass cap (removable with a drill) covering the holes for the pilot fuel screw.

[adam77gs550]

Thanks, Ned; after running SeaFoam through it and richening the pilot air screw, this morning it took about 3-4 minutes to come off the choke, after which it ran perfectly. I think I can live with that since it never has any problems for the rest of the day. It only requires the "prime" position first start in the morning also. I will check on the manufacture date; it's titled as a '77, has spoke wheels, and nothing on it is aftermarket.

Adam

[hampshirehog]

Unless you're at altitude you should leave all the settings to standard (maybe, as you have done, tweak the pilot airscrew in a tad).

You should be warming up a lot quicker than what you're telling us though. I'd pull the carbs and do a rebuild - new rubbers etc. Once you twig how a bank of VMs work it's a pretty easy job (though first time re-fitting the airbox will probably have you cussing - there's a knack to it and it's a lot easier 2nd time).

Balancing is also absolutely key on the 550 - they're much fussier than the bigger bikes.