Deleted
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Post by Deleted on Aug 24, 2011 22:45:18 GMT -4
Ok so I wanted to build my own cafe. 5 years later I traded my non-runner for a snotter. It runs real nice like. So can anyone tell me why the fuel leaks out? I always turn off fuel but it always seems to leak and smell up garage. I was told the floats may need adjusting. Any other advice and a quick how to would be awesome.
Glad to be here. Looking forward to learning something too. Cheers!
Oh, this might help. '73 cb750.
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Post by indyfour on Aug 25, 2011 6:20:17 GMT -4
Welcome!
I suppose it could be the floats, but it could also be the fuel petcock. If fuel is left on or if your petcock leaks, even properly set floats won't stop fuel from coming out the carb overflows.
I think the '73 had a couple different types of petcocks....if you have the type with the sediment bowl on the bottom and two fuel outlets, it could be that the dial seal behind the shutoff lever is worn....but (from my experience) it's probably more likely that the fiber washers on the two screws holding the petcock to the tank are all shriveled up and no longer sealing properly. This allows fuel to pass through the petcock even in the "off" position...and to the carbs when the bike is parked.
I'm not really familiar with the other type of petcock that threads onto a nipple on the bottom of the tank and has an in-tank filter. I would imagine it also has a dial seal that could be worn?
So my advice is to check the petcock before pulling your carbs out to work on floats. Pull the fuel line off the petcock nipple(s) and see if fuel flows when it's in the "off" position. Even a slow drip could cause your leak.
Good luck.
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Post by tango911 on Aug 25, 2011 7:57:26 GMT -4
ALso, where is it leaking from?
Carb bowl drain? Once we know the answer we can direct you to the proper fix for sure. As is could still be the Pet cock.
Pull the hoses off the pet cock with it turned off. if it still comes out you know your petcock leaks.
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barnfinder
Training Wheels
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Post by barnfinder on Aug 25, 2011 10:40:13 GMT -4
Also, if its from the carb bowls you might have "weeping bowls."
Its when the overflow tube splits. Sometimes its barely visible. But they will run the length of the tube, or right in the sweet spot where the fuel level should be.
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Post by tango911 on Aug 25, 2011 12:46:25 GMT -4
+1
a good fix for that would be heat shrink tubing if thats the case.
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Post by williamc89 on Aug 25, 2011 21:16:17 GMT -4
u can rebuild the petcock the kits are cheap and that might fix the problem like the guys have said , but see were its from to, u may fix it cheap , it dont sound like u have a big problem...
hey does it do it when its runing ,,,, and a way u can check the petcock some times is to have the bike runing and just turn off the fuel and let the carbs run out of fuel and see it leaks , if it doesnt run out then u know ur problem
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Post by Deleted on Aug 27, 2011 15:22:46 GMT -4
Wow, thanks guys. It only seems to leaf when parked. Petcock is always off. Leak is coming from overflow tubes. Fuel runs down frame onto floor. So in my estimation I should start with the petcock and work my way in.
Next question ... When cruising I get a popping sound like a small backfire coming from the cylinders it seems. Not out the exhaust. When I get in it it seems to stop but then it hesitates at higher rpm. Would this be in the ignition? To my knowledge it is original equipment except for maybe the plugs. Keep the advice coming and thanks!
Cheers!
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Post by tango911 on Aug 27, 2011 16:14:31 GMT -4
could be timing or valves.
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Post by williamc89 on Aug 27, 2011 19:39:03 GMT -4
do u have vacum diaphames sorry if i didnt spell that right,, i had a bike that did that and it loss vacum and it wood pop like that
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Post by leadkrm on Aug 27, 2011 21:22:08 GMT -4
The popping is probably coming from cracks in ur intake boots between ur carbs and head.
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Post by Deleted on Aug 27, 2011 23:09:46 GMT -4
Cracks in the boots. I can check that easy enough.
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Post by leadkrm on Aug 27, 2011 23:28:10 GMT -4
Yea even if they are faint and don't seem like they could be the problem they still probaly are
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Post by novafrk on Aug 29, 2011 15:27:36 GMT -4
Have you made any progress on the leaking fuel? I want to put my two cents worth in. I'd suspect a bad needle and seat as a possible cause. Depending on how long and where it sat and what type n&s it is. (I've seen metal on metal, metal tip on rubber and rubber tip on metal) the rubber type gets stiff and doesn't seal well. The metal on metal type gets crud built up on them especially after sitting for years.
It's almost always a good call to completely go through an old bikes fuel system. Seems to save many headaches down the road.
Keep us posted.
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Post by hogsausage on Aug 30, 2011 10:48:13 GMT -4
Waggs, another trick to find exactly where the leak is coming from is to run all the gas out of your float bowls. I do this on my Triumphs out of habit because Amals like to leak anyway. I usually shut my gas off about a half mile out from my house and by the time I pull in my garage they are usually dry. If you are still have gas leaking the next morning you probably have petcock issues. If its dry, your overflow may be just doing its job depending on how much gas you have leaking.
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Post by Deleted on Aug 30, 2011 20:52:23 GMT -4
I tried turning off fuel before I arrive home and that seems to really help. When I first got the bike I had a mechanic go through the brakes, fuel system, etc and he put new jets in it then. Might just be too much fuel in the bowls when I park it. I'll keep whittling down the ideas. Thanks everyone.
Really enjoying the forum btw!
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