[Zoltar]

I recently picked up a set of 48 to 50 Pan tanks in good condition for my current project. One has a stock cap.The other cap has G.M.E. stamped on the under side bayonet. Looks old and fits well. Any one have any knowledge of this type of cap?
Thanks

 

[slim55g]

If i recall correctly, GME made many different aftermarket parts for bikes, gas caps were one of many. If you want an eaton, i have them to. Streck made them also for some models.

 

[Zoltar]

Thanks for the info Slim. As I get closer to putting the bike together (this winter)I will most likely contact you if I feel i need an Eaton as i don't have one laying around. Not going for a restoration. Building a mutt pan out of my spares. 55 Fl motor all finished. 57 trans all finished. Stock glide front end with new tubes and lower leg bushings. Cleaning up the 51 frame now. Going for an early 50's Bob Job style.

 

[HD48FL]

As Slim mentioned, Eatons are what came as originals.

One is vented and one isn't, I believe.

 

[slim55g]

Left cap is non vented, right is to aid in crossover fuel dawing evenly from both tanks

 

[old.wrench]

Zoltar.
Just to clear this up, if you have original unmodified '48-'50 tanks you need to run a vented cap on both tank halves. The unvented left tank cap came about with the addition of the vent crossover tubing at the top of the tank under the dash, but that didn't show up until much later (60's) along with the bottom mount petcock. I'm sure somebody will come up with the exact year it changed over.

Regards,
Geo.

 

[Zoltar]

Geo
The tanks are stock. I do have one vented Eaton cap. My oldest tanks are a set of 59/60 and I have run them with no vent caps with no problems. I honestly don't recall if they have the crossover on top as it has been a long time since i built the bike. The GME cap does not appear to be vented so I will be contacting slim down the line. Thanks for the info.

 

[Rubone]

Geo is correct, both sides are vented and need to be. On the later tanks with a crossover line under the dash the neck depth is different to prevent mixing up the vented and non-vented caps. Early non vented caps are for 45 oil tanks.
Robbie

 

[old.wrench]

Just so nobody gets the wrong idea about maintaining a reliable, steady fuel flow-- you have to vent your gas tank somehow, otherwise you WILL have a problem with your fuel flow. No air coming in to equalize pressure in the tank = no fuel coming out of your fuel line. The way that was accomplished with the older tanks (pre '65?) without the crossover vent line was with a vented cap on each tank half. That also led to the problem of gas leaking thru the left tank vented cap if your tanks were all the way topped off and your bike was leaned over on the side-stand. What I'm thinking Zoltar, if your bike ran good with the '59-'60 tanks with an unvented cap on the left tank, I think either your gas cap had a bad gasket or you were sucking air thru the fuel/reserve shut off rod assembly on top of the left tank. I'm specifically talking about Harley split tanks here but this venting principle stands true for any gas tank.

Regards,
Geo.

 

[Zoltar]

OK now for my dumb question. Is there a simple way to tell if the cap is vented? I am ready to learn some thing I should have known a long time ago. Thanks guys

 

[Cotten]

Zoltar!

Here is a pic of one kind of Eaton cap on the left;
(On the right is a common repop where the gasket swells to cover the vents, with disastrous results.)

....Cotten

 

[Zoltar]

Cotten
Thanks for the pics. Just what my dumb ass needed. The GME cap I have is vented after all as it looks just like your Eaton photo. Plus i can blow through holes on the perimeter of the cap and feel air coming through the center of the bayonet.
I have installed one of your floats in my Linkert M 74B for my other bike. Great results. Thanks!!