Bloody Carbs!

[Anonymous]

Hi All,

I have a 1978 GS550E and am having trouble with my centre left carburettor. It floods everytime I take my bike for a spin, on start-up, while riding, and when I come to a stop. When the engine is off, and the petcock turned to prime, the carb will flood out if I give the bike a little wobble. I have adjusted the float level numerous times, and replaced the float needle twice, but still no joy. I have taken it to a SUZUKI mechanic and he went through much the same process, thought he had fixed it and the next day I took it out it started flooding again!

Also, it is a real pain in the ass to start, it will take a couple of minutes to start if it has been left for a couple of hours or overninght and I find I sometimes have to use aerostart to get it going. Somebody mentioned to me that there is a little valve or tube in the carbs that could be drilled out minutely to fix the starting problem, but I am not sure what he was referring too. Any ideas?

The bike runs great when it is going, except for when it gets to about 6000RPM where it will cough and splutter again (due to the jet needles being pretty old and worn I think), however, I don't really ride it that hard anyway. Keep the revs below this and its fine, and will do 100 - 110km down the freeway comfortably.

All four carbs have been rebuilt with new components except for Jet Needles, Float assemblies and Throttle valves which I cleaned up best I could.

Any helpful tips or problem solvers would be much appreciated!

Cheers,
Paul

[isaac]

I'd guess that your float isn't floating, is still too low, or the fuel inlet valve controlled by the float it sticking open and allowing too much fuel in. If you're a contortionist with small hands I bet you could see that with the carbs still on the bike, but it only takes 10 mins to get em off anyway.

[earlfor]

Remove your float needle assembly. Underneath it is an "O" ring. When this "O" ring gets worn or brittle, the float raising does not shut of fuel to the bowl because fuel leaks past the needle and seat and the bowl is always flooded.
It has the same effect as if you had no float in the bowl at all. Replace the "O" rings on all four carbs. If one is gone, the rest are not far behind.

Earl

[earlfor]

Re: Bloody Carbs!

I know exactly what he was referring to and he is wrong. Dont drill out anything unless you want to be buying new cars. There are two circuits responsible for starting, the idle passageways and the choke tube. The passages are small and the only safe way to clean them is by soaking the carbs and blowing the passages out. Dont even think of trying to drill out either of these.

Earl


[quote="p_giowa"]Hi All,

I Somebody mentioned to me that there is a little valve or tube in the carbs that could be drilled out minutely to fix the starting problem, but I am not sure what he was referring too. Any ideas?

[beby99]

Could the float itself be filling with gas? :?

[Jethro]

Make sure you run a piece of wire or something through the starter jet and make sure the fuel feed port in the float bowl cover itself is clear.

[Anonymous]

Earl, you're probably thinking of the 'BS' series valve seat. This bike is a '78, so it's probable that the carbs are 'VM', which use just a washer under the valve seat.

I'd say that narrows it down to the seat & needle. I haven't checked if those parts are available separately for a VM.

I often wonder why these start leaking anyway. What changes? When I pull them apart, there's nothing visible that could cause problems... I could see if there's wear on the tip, but there rarely is. Perhaps the bore for the needle roughens up a bit from the fuel exposure over the years. Maybe polishing that bore would decrease the likelihood of a sticking needle. (How to polish? Q-tip and valve lap compound?)

Anyhow, I'd look at R/R the valve seat & needle from that carb. Since you're in Australia, I can't suggest any parts sources for these.

[Anonymous]

carb

Think that the problem is the float is loose on the pin and is hitting the side of the float bowl or is vibrating around, and not letting the needle stay seated a simple but careful crimping at the pin will cure it, just dont get it to tight! also line sight the floats(L-R) and make sure there level with each other, so its not bobbing off to one side

[earlfor]

Yeah, I was. Too many late nights I guess. :-)

Earl

[quote="robertbarr"]
Earl, you're probably thinking of the 'BS' series valve seat. This bike is a '78, so it's probable that the carbs are 'VM', which use just a washer under the valve seat.

[Anonymous]

1978 GS550E Carbs

Hi All,

Thanks for your replies so far! I guess I'm going to have to pull the carbs back off...

Does anybody know where I could source four new (or new old stock) Jet Needls and Throttle Valves for this particular bike - I might as well do them while the carbs are off. Most parts I have got already have had to be shipped from the US, so if you have any suggestions, that would be great!

Cheers,
Paul