Carb problems on a 1978 550

[brainrush]

1978 Suzuki GS 550 E. I got some used carbs yesterday as the old ones had the fuel screws stuck in the carb bodies. even with the new(er) carbs, I can't get it to idle without choke, static timing is dead on, good spark, compression is a little low across the board, about mid 90's (worn rings) but even if I put a touch of oil in the cylinders to bump up the compression a bit it doesn't want to idle without choke. When the throttle is pulled, sometimes it'll rev, most the time it will just die, plugs 1&2 are sooty, plugs 3&4 are wet, I can't find any air leaks. I haven't touched the carbs yet other than screwing the air screws to 1.5 turns out. it's got an old 4-1 exhaust and pod filters so I'd expect it to run a little lean but not this lean. from the sootyness I'd say its running rich. I'm confused!

The carbs are Mikuni VM22SS's

 

[brainrush]

I think I found the problem... fuel screws are all stuck in the carb bodies...again... I'm really ticked off right now. I'm going to try and recover them, but I'm feeling pretty irreconcilable at the moment.

 

[TheCafeKid]

I think I found the problem... fuel screws are all stuck in the carb bodies...again... I'm really ticked off right now. I'm going to try and recover them, but I'm feeling pretty irreconcilable at the moment.

Did you clean and dip the carbs? It is a MUST. Cutting corners will only serve to keep you ticked off and irreconcilable...

 

[Guest]

Heat those screws up with a propane torch and some PB Blaster. They come right out. Do not bugger up the head. If it gets hard more heat and PB.

 

[brainrush]

Only the tips were stuck, I was able to remove 3 of the 4 using a socket and gently pressure, the last one doesn't have the tip exposed, so instead of making the same mistake I did last time and try and make a tool for it, I'm going use use some of my practice carbs (ug!) and put them in boiling water, then try and get them out of there, it it works a treat, I'll just replace the carb body and in the mean time try and rescue my first set of carbs. Except for the outside and the fuel screw, everything else looked really fresh. BTW, does anyone know a good source for fuel screws?

 

[brainrush]

After some boiling water I used most of it to mix with murphy's and detergent (I used the rest to make ramen) I set the carbs in there, I didn't have much luck with the old carbs, so I tried the new carbs, (this time the rest of the boiling water went to some late night hot cocoa!) and with a sharpened staple and a bit of luck it popped right out! no visible scratches either. I re-assembled the carbs moving the jet needle to the richest position in anticipation of the aforementioned pods&pipes my engine came with. Now for some fuel screws...

 

[Nessism]

The only place I know to get the fuel screws is in the K&L GS750 rebuild kits that Z1 Enterprises sells. The fuel screws are not available from Suzuki anymore and are not sold aftermarket from any source I've found. You can get Kawasaki fuel screws but they cost more than the rebuild kits so that's no help. You might want to try the Parts Wanted forum.

 

[brainrush]

Thanks for the info, I'll post something there, in the meantime, I'll try turning my exhisting screws on a lathe to get something usable.