Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties Fuel leak carb

Fuel leak carb

Post Sat Jan 04, 2020 2:12 am

Posts: 255
Location: Orlando
Hello PA Cotton
I now have 6000 miles on my WLA and it is running better than ever.
However, I am experiencing a fuel leak when sitting, just like PA's leak
It's weeping through the bowl and carb seat (no gasket) metal on metal.
I believe my cork float may have finally loosened an/or the float valve is worn. I am still running it every weekend so I don't want to pull the Carb until I acquire the right stuff.
I want to stay away from the copper floats.
Since you guys went through extensive troubleshooting on this PA's leak what would you recommend I purchase as far as float, needle, and gaskets and where to purchase. Cotton's custom float looks pretty sturdy.
I want to shotgun the carb on a weekend and be back up quickly.

Oh, My fuel shutoff seems to have a really slow leak, Any tricks to seat it better ?

Grateful for your input.


Post Sat Jan 04, 2020 3:36 pm
Pa Site Admin

Posts: 6226
Location: Ohio USA

Great to hear the bike is running great Brendan. :) I recommend Cotten's float and would keep a spare on hand since fuel makeup changes so often. As for the fuel valve sealing, I leave that to the guru Cotten. I am sure Cotten will advise on what to double check before you proceed with parts replacements or repairs.

Post Fri Mar 06, 2020 11:18 am

Posts: 27
Location: Snohomish Co., WA
I recommend Cotten's Durable floats as well, and have installed three of them on my Linkert carbs. An important point to keep in mind is to make sure the float is installed so that its top is 1/4" below the rim of the bowl, and that it moves freely through its arc without contacting either the float bowl or the bowl stem. Cotton let me in on a trick to check this -- use a dry-erase marker to "paint" any potential points of contact, put the float in and secure the float bowl with the stem nut, and then turn the carb upside-down a number of times. If there is any contact between the float and the bowl stem, you'll see places where the marker has rubbed off. When you turn the carb over each time, you should be able to hear the float moving.

Once you get the float in the right place, be sure to use something to seal the float lever screw. I think I used "Right Stuff" to do this, but I'm not sure. You want something that doesn't dissolve in gas/ethanol. Also, I use a gasket between the float bowl and the carb body on my M-88. I don't think it was used originally, but I don't see any harm in using one.

Regarding the fuel shutoff, I replaced the shutoff on my Panhead with one I got from Carl's Cycle Supply ( Their shutoff features PEEK seals. They don't seem to list it in their catalog, which hasn't been updated for about 8 years, but I was able to contact them by email (or maybe snail mail) and get one. As I recall it was about $140. I haven't had any problems with gas leaking from the shutoff from my WL, so I left that one alone.

Good luck!

Post Sun Mar 08, 2020 10:16 am

Posts: 3553
Location: Central Illinois, USA
A couple of notes, Folks,...

Determining the position of the float requires placing the bowl upon the body in its correct position, and then flipping both upside-down for the 'suck test'.
Variations in stem castings, even among similar models, can make for difficulties, that 'dry-erase' ink can illustrate.
Most often it is upon the gallery shown in the attachment.
(I confess to relieving some bowlstems to assure clearance in the future...)

The adhesive upon the screw is not to prevent it from coming loose.
If it is firm upon the barrel of the nut, there is nothing to loosen it. But floats can come loose.
The adhesive is to secure the float to the lever itself.

My floats are cut so the lever fits tightly in the notch, and the foam compresses slightly beneath it.
The adhesive then bridges the two 'ears' above the lever and screw to secure it.

USA fuels are constantly changing, but lately, "Seal-All" and "JBWeld" are surviving better than they did.
(I use an isocyanate urethane.)

I rarely replace a fuel valve, unless the hex is just too ugly, or it won't pass the 'suck test' after placing the needle in the seat on a firm surface and smacking it a couple of times with a wooden screwdriver handle.

My current choice for replacements is Colony's, but even those need whacking!

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Post Tue Apr 28, 2020 8:33 am

Posts: 255
Location: Orlando
I installed the Float you sent me and it is working just fine. The leak has stopped. However, I noticed My bike is leaning more than it should (comparing it to many other pictures). It seeps for a tiny bit and stops after I come in for a ride. I put a piece of plywood under the side stand and have o.o seeping from carb bowl. Thank you

Post Tue Apr 28, 2020 9:29 am

Posts: 3553
Location: Central Illinois, USA
If it stops leaking reasonably when parked, Brendan,...

Then you are at least lucky enough to have a good petcock!

Please do not use heat to bend your jiffy stand!

Can you see a way to shim the assembly to an advantage?

PS: Although I completely assembled a couple, I haven't touched a 45" chassis in decades.

Post Sun Jul 05, 2020 8:40 pm

Posts: 255
Location: Orlando
I am going to relieve the bowl stem. I do not want to go deep. how much do you recommend ? It started seeping again after a long ride. I took it apart and ensured the seat is working by putting it on a test stand with a fuel line attached overnight. (Without the bowl stem inserted) just corked the hole in the bottom of the bowl. I really do not think it is hitting the stem. The float bounces when I give it a shake/tap while it is fully assembled. So, I want to eliminate the possibility that my tapping and hearing the float bounce is not a false positive.

Post Mon Jul 06, 2020 2:14 pm

Posts: 3553
Location: Central Illinois, USA
There's plenty of meat to work with on the bowlstem, Brendan!

The indexing of the floatvalve beneath the HS needle is aided by removing some of the ledge at the bottom of the bowlstem.

Metal can be removed at any of the arrows with impunity.

The notion of checking a valve by setting it up on a stand is folly. I did it enough to know.

Once again, the petcock should shut off fuel when the machine sits. The floatvalve is designed to work open, and only shuts effectively for a short time.

If it is drool caused by the angle of jiffystand, then some could be coming from the pivotbearing screws, or more likely from blemishes at the top of the bowl, where a gasket was not spec'd. I cut thin paper ones anyway.

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