Topic: Bike pissing fuel after sitting

[CBDee]

Hi. My '74 cb550 keeps pissing fuel on the floor. Only happens after it sits for a couple of hours. Have the petcock on the off position. One thing I noticed was that the petcock drips even in the closed position. Could this be part of the problem? Carbs are newly rebuilt, should I re-check float heights? Thanks for any replies.

[tool14]

check floats again and petcock does shut off.

[CBDee]

Thanks, tool. Noticed it does it worse with a full tank, so guess it must be a combination of a leaky petcock and bad float heights. Will pull the carbs and check floats and buy a real Honda petcock instead of the aftermarket pos I have on there now.

[bryanj]

Fibre washers under the screw heads holding the petcock on

[ekpent]

  Fix the petcock before messing with the carbs.

[1976cb750f836]

Fix the petcock first! Mine was seaping by the bowl drain screw?

[Bankerdanny]

When the carbs were rebuilt did they get new float needles and seats? If they did, were they genuine Honda parts? I had all kinds of leaking issues with my 550F carbs until I broke down and installed a complete set of OEM Honda needles and seats.

[CBDee]

Thanks for the replies. Th he petcock leaks thru the house connections, like there was an internal leak. Tried tightening down the two external screws which didn't help - just made it harder to turn. The carb rebuild kits were aftermarket, not Honda, so thanks for the tip. Will replace the petcock first as it's a lot easier to get to.

[Bankerdanny]

Thanks for the replies. Th he petcock leaks thru the house connections, like there was an internal leak. Tried tightening down the two external screws which didn't help - just made it harder to turn. The carb rebuild kits were aftermarket, not Honda, so thanks for the tip. Will replace the petcock first as it's a lot easier to get to.

Did they return the original jets and needles to you when the job was done? Aftermarket jets are notorious for not being the sizes they say they are and the needles not having the correct taper profile. The carbs rarely need a "rebuild." 99% of the time they just need a good cleaning and new gaskets and O-rings.

Obviously deal with your leak first, but down the road if you have issues with poor idling or running lean/rich that you can't seem to solve the replacement jets and needles could be the culprit.

[DanJ]

Mine did the same thing. I bought an aftermarket petcock and was just as bad. Ended up buying a new Honda petcock and problem went away.

[CBDee]

Thanks for the input, Dan. Just ordered a Honda petcock from DSS.

[HondaMan]

Another thing: check the fuel cap's vent. If the bike was run and then parked, it heats up the tank. If the fuel cap vent is blocked, it pressurizes the tank quite a bit: I have heard the seal 'burping' on a 550 after it was ridden to my house one hot summer's day and parked while we cooled it with a big fan: when I opened the gas cap, it 'popped' and his gas leak (that he came to see me about) stopped like magic! Too bad I couldn't fix the cap, he had to get a new one...

[CBDee]

Good suggestion, Hondaman. I've heard some "wheezing" from the cap area before. Maybe I'll just open it up after parking to see if it makes a difference. Thanks to all who have replied. Really appreciate the help.

[bryanj]

If the petcock is held to the tank with two screws inside the float bowl you need new fibre washers under the bolt heads and generic ones do not work you need to bite the bullet and buy the expensive Honda ones!

[Bailgang]

Another thing: check the fuel cap's vent. If the bike was run and then parked, it heats up the tank. If the fuel cap vent is blocked, it pressurizes the tank quite a bit: I have heard the seal 'burping' on a 550 after it was ridden to my house one hot summer's day and parked while we cooled it with a big fan: when I opened the gas cap, it 'popped' and his gas leak (that he came to see me about) stopped like magic! Too bad I couldn't fix the cap, he had to get a new one...

+1 to that. A friend of mine had the same issue with his 1200 HD Sportster, once he explained when it was happening as in it only did it when parked after a ride and the engine was cooling down, that's when it dawned on me. A new cap took care of it. Not saying that's you're problem but definitely something to consider.

[CBDee]

Thanks for the replies.
Bryanj, ill give it a look, but still going to get a new petcock. I suppose it could be leaking there and filling up the petcock bowl. But, you'd think it would leak around the bowl, not thru the spigot.

Bailgang, it sounds like a good theory, but it happens even when I haven't ridden. Ill come out in the morning and there's a puddle of gas under the bike. I clean it up and come back later to a new,puddle. It does it just sitting there. I've heard of these bikes leaking if the valve is left open over night, which led me to suspect the leaking petcock.

Ill try leaving the gas cap,open while it's sitting there to alleviate that potential problem, but I suspect it's my cheap petcock and probably bad float heights that are causing the problem.