Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: ramblingroger on September 03, 2007, 04:35:03 PM
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Just purchased a 1979 sr500, it has been stored for 23 years, got it home absolutely over the moon, completely original. I have checked it out and the brakes work, lights, and got it started for 5 minutes. I cleaned the tank out, removed the carburator, rebuilt it with a kit, float and valve, everything OK. It did start briefly and then petrol poured out of the bottom, I did put it on prime then switched to on, as per instructions. Removed the carburator again, checked it and the same result. Bought another carburator on Ebay identical except the vacuum valve was blanked off. I think it was off an XT500, connected that up and the same result petrol poured out of the bottom, floating valve in good condition. The question is: What can I do next? This is stopping me from leaping on my brand new acquisition and riding off into the sun set!
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see this is a strange one, it happened to me once or twice on my 1980 sr500. Ive never ever had mine on prime though and it only ever happened if the bike was sitting idling for a long time. Strangely enough it stopped when i bought a new airfilter! I have no idea whether this was related or not but it may be worth a try.
Is she running the correct air/fuel mixture?
If youre looking for parts try here: http://shop.wemoto.com/index.dyn?oid=5835691 (http://shop.wemoto.com/index.dyn?oid=5835691)
Or for more specific advice try the sr500 forum here: http://sr500forum.proboards38.com/index.cgi#General (http://sr500forum.proboards38.com/index.cgi#General)
Hope this helps some.
Damo
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Hi There
You say petrol is coming out of the bottom.. Bottom of the carb? If so it seems strange that the leak is on both carbs?
Is the leak further up - fuel tap, fuel line, and the petrol running down and dripping / flowing from the bottom of the carb?
If it is the carb, did you take the new one apart? if so have you got any gaskets etc in the right way round and the right way up? - Duplicate leaks on the two carbs may be the same cause.
Is this with or with out the engine running? - Is it a vacuum tap? - If so the XT one should not work?
Just some thoughts
R
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What carb is it you have? is it the standard mikuni vm34ss from the sr500? does it have an accelerator pump or is it pump free? the float bowl vent could be blocked or the choke may be jammed? does the fuel pour out of the overflow pipe under the carb?
(http://www.siue.edu/~rsutton/SR/carblft1.jpg)
is this ur carb?
Damo
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if the float height is adjustable, its possible that it is incorrectly adjusted, or the 'pin' that blocks the inlet is worn. either way the float could be right at the top of the float bowl, but not seating the 'pin'.
bullet350
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As has been said it's far more likely that fuel is leaking down above the carb and dripping off the carb base. The chances of both carbs exhibiting the same fault is pretty remote
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hi ive had fuel leaks (20 litre tank)a few times over the years my were to do with the petcock there is no off only run prime and reserve had to clamp the fuel line .on the top right as you look at the petcock there is a small hole i think this is a breather so the diaphragm behind can move ive drained the fuel tank took the petcock apart cleaned the diaphragms put together again and alls been well hope this helps steve