Stumped, need advise

[WayMMetal]

Hey guys, new member, sweet website. I recently bought an 83 650gl and rode it for about a week before it started acting up. Now whenever i turn it on it immediately red lines to like 7 or 8 grand, even letting out on the clutch it accelerates to the top of the gear. Opened up the carbs and there was a large hole in one of the diaphragms, patched it and it fixed the problem for about 2 miles then it started doing it again. I have tried completely cleaning all 4 carbs, including needle valves, Ive synced them up using the tool, adjusted the fuel screws( not really sure the correct term a mechanic buddy told me to try it) and every time it fixes the problem for a few miles then starts up again. Any advise would be most welcome.

[tom203]

Hey guys, new member, sweet website. I recently bought an 83 650gl and rode it for about a week before it started acting up. Now whenever i turn it on it immediately red lines to like 7 or 8 grand, even letting out on the clutch it accelerates to the top of the gear. Opened up the carbs and there was a large hole in one of the diaphragms, patched it and it fixed the problem for about 2 miles then it started doing it again. I have tried completely cleaning all 4 carbs, including needle valves, Ive synced them up using the tool, adjusted the fuel screws( not really sure the correct term a mechanic buddy told me to try it) and every time it fixes the problem for a few miles then starts up again. Any advise would be most welcome.

A hole in a diaphram would be serious intake air leak,letting revs climb with no throttle input, but it wouldn't let engine run away with clutch engaged- unless your throttle plates are being held too open. If you spent some time on this site, you've probably discovered that carb cleaning is serious business- how did you clean yours?

[Steve]

A hole in a diaphram would be serious intake air leak,letting revs climb with no throttle input, ...

Not sure about your carbs, Tom, but all the ones I have seen have had the diaphragm on the unpstream side of the throttle.

Yeah it's air flowing through a wrong source, but it's still air that has to then flow past the throttle butterflies.

WayMMetal, you can not "patch" the diapragms with any degree of success, you need to replace them. New ones are VERY expensive, hopefully someone here has some in good shape for you.

Check your cable routings if they go past the carbs. I don't remember how the 650 clutch cable is routed, but my 850 cables go past the throttle linkage and have a retainer to keep them away. If the retainer is missing, some very exciting times can result.

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