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Motorcycle Repair/VT500c leaks gas when starting


Hi, I just tried to start my 84 vt500c after its three months "winterholiday" in a heated garage. I almost got it started but it died on me, we noticed however trying to restart that fuel is leaking at the bottom end of the kickstand. carboretors, fuel tank seems to be dry. I was unable to get it startedm again. Any ideas in which direction I should be looking. All help appreciated.


Hans (from Holland)

Hans, if you follow the drain tubes from the carburetors, you will probably find they exit at the back of the engine near the centerstand. If there are no drain hoses on the carburetor bowls, it could be fuel backing up in the venting system. Look online at CMSNL.COM for microfiche illustrations to see the components involved.

I don't know if they have better gasoline in Holland than they do in the US, but ours really doesn't last 3 months before separating and evaporating leaving sticky varnish deposits that can cause the float valves to stick open/closed creating the flooding condition you describe.

If your bike has the vacuum diaphragm on the side of the fuel petcock, the diaphragm may have failed which causes a vacuum leak into the engine and a fuel leak externally, as well. Repair kits are available to replace damaged diaphragms.

Always drain the fuel bowls before going into winter storage and use stabilizer in the fuel tank, as well. You may have to remove the carburetors and clean the float valves and any residues in the float bowls before you can get it going again.

Understand that when the float bowls are dry, the only way for them to fill up is for vacuum on the diaphragm. Try using a small vacuum pump on the vacuum line fitting to open the fuel valve and allow the bowls to refill before starting the engine again. Check to see that the choke valves are not gummed up, as well.

Bill Silver  

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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