‘75 GT550 carburetor questions

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GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: ‘75 GT550 carburetor questions

Post by GTandcbr »

If you intend keeping the bike this tool makes float height an easy task.
https://www.ebay.co.uk/itm/Suzuki-GT750 ... SwnLdWrojv" onclick="window.open(this.href);return false;
Or make one yourself i did
98 carb Blackbird and GT550j
pgb123
Around the block
Posts: 89
Joined: Fri Nov 30, 2012 8:27 am
Country: USA
Suzuki 2-Strokes: GT550

Re: ‘75 GT550 carburetor questions

Post by pgb123 »

Ok, so something strange happened. I replaced the petcock with a new one and the fuel leak stopped. Not just the leak from the petcock, but also from the carb overflow tubes! Why would that be?

Also, funny thing. The bike surged at idle. I couldn’t really hear it, but the odometer bounced all over the place. I adjusted the air screws and thought I fixed it. While riding yesterday, the needle started bouncing again. Turned out I didn’t insert the odometer cable correctly when I repaired the gauges. Duh!
GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: ‘75 GT550 carburetor questions

Post by GTandcbr »

Okay the likely source of your overflow problem was that the diaphragm in the petcock was stuck open and therefore petrol continued to flow even when the bike was switched off. Which would be like leaving it in the prime position. Glad to see you have solved some of your problems
98 carb Blackbird and GT550j
pgb123
Around the block
Posts: 89
Joined: Fri Nov 30, 2012 8:27 am
Country: USA
Suzuki 2-Strokes: GT550

Re: ‘75 GT550 carburetor questions

Post by pgb123 »

It didn’t flow while the bike was off. The petcock leaked only when it was running. The other issue was that fuel came out of the carb overflow tubes at a pretty steady rate while it was running. I figured I needed to adjust the floats, but when I replaced the petcock, the carb overflow problem disappeared. I just don’t understand why.

In any event, I’ve finally gotten a chance to really ride this bike and it’s awesome!
GTandcbr
Yeah Man, the Interstate
Posts: 590
Joined: Tue Mar 10, 2015 12:35 pm
Country: WALES
Suzuki 2-Strokes: suzuki gt 550j
Location: Wales

Re: ‘75 GT550 carburetor questions

Post by GTandcbr »

There are only 2 things in the system to control the fuel flow,the diaphragm in the petcock and the float level needle valves. I suggest that perhaps the needle valves were unseated but sorted themselves with the engine vibrations? Anyhow it's all sorted for you now :D
98 carb Blackbird and GT550j
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