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Thread: Opinions on my Oil and Gas Caps condition please.

  1. Opinions on my Oil and Gas Caps condition please.

    From my '48 Chief
    Oil (top) leaks the odd drop so not really an issue but the other two look totally different and leak a lot when the tanks are full. The gas caps don't appear vented either as I don't see any small hole. Are they correct but need new gaskets or should I get new ones altogether?



  2. Re: Opinions on my Oil and Gas Caps condition please.

    Howdy sir,

    Gas caps, get new repop or if persnickety about originality least expensive route is to locate ex military in olive drab and have them chromed. NOS turn up on eBay periodically. Original gas caps had prominent center hole in top and visible flap valve type vent mechanism on the underside. Don’t see topside of oil cap, originals have very crisp letter stamping, repops more rounded.

  3. #3

    Re: Opinions on my Oil and Gas Caps condition please.

    Quote Originally Posted by peterg440 View Post
    Don’t see topside of oil cap, originals have very crisp letter stamping, repops more rounded.
    Right...those gas caps don’t appear vented, they’re not 1948 style but certainly could be old. What do the tops look like?

    As far leaks go....I put two of Greer’s cork gaskets in there, but there’s other things to do, too. A well vented cap and a tight seal of cap to filler neck is important.
    1946 Chief - take apart and put back together
    101 Scout - building stage

  4. Re: Opinions on my Oil and Gas Caps condition please.

    It is hard to say if your gas caps are vented or not. It is important to have vented gas caps. Non-vented gas caps have been associated with ruptured long seams on soldered gas tanks. I have personally had a non-vented cap cause a carburetor flooding problem by tank pressure causing the needle/seat to unseat when the bike is sitting in the hot sun. A non-vented cap can also prevent gasoline from dropping - causing a fuel starving condition at the carburetor. Peterg440 mentioned military gas caps, and they do show up on eBay and at swap meets. Those surplus military gas caps used to be a dime-a-dozen, but they have now become considerably more expensive. Below are two photos of a military gas cap. The civilian caps are similar but are typically chromed. Notice the hole in the middle of the cap top. On some of the later Chiefs, the caps were painted bike color; supposedly using-up left over Army surplus caps that the factory had. In a pinch, a cap can be drilled to give a positive vent. The problem with that trick is if the bike tips over, gas will stream out of the vent hole. That happened to me once with the engine running - and luckily the engine stalled before the bike caught fire. That reminds me - I need to buy new vented gas caps.

    NOS Military Chief gas cap A by Steven Bailey, on Flickr

    NOS Military Chief gas cap B by Steven Bailey, on Flickr

  5. Re: Opinions on my Oil and Gas Caps condition please.

    Thanks all for the confirmation. New caps just ordered.

  6. #6

    Re: Opinions on my Oil and Gas Caps condition please.

    Original oil caps have more space between letters compared to repo caps. You may have to disassemble new gas caps to cut pressure spring down as they hold too much pressure in tanks and will push gas past needle.

  7. Re: Opinions on my Oil and Gas Caps condition please.

    As mentioned previously, original oil caps have crisper letter stampings, and the spacing between the letters is wider than the spacing using on reproduction caps. The reproduction cap in the photo below is the type that Jerry Greer sells. Though the reproduction oil cap may not be 100% correct, it is a lot better than no oil cap.

    Indian Oil Cap Comparison by Steven Bailey, on Flickr
    Last edited by Yellow53Chief; 05-27-2019 at 10:43 PM. Reason: Spelling error corrected.

  8. Re: Opinions on my Oil and Gas Caps condition please.

    I only ordered gas caps and they state that they are vented so that should prevent any pressure build up

  9. #9

    Re: Opinions on my Oil and Gas Caps condition please.

    Quote Originally Posted by SPEIRMOOR View Post
    I only ordered gas caps and they state that they are vented so that should prevent any pressure build up
    You may have to disassemble new gas caps to cut pressure spring down as they hold too much pressure in tanks and will push gas past needle. This is what happened to my motor with those replacement caps.

  10. Re: Opinions on my Oil and Gas Caps condition please.

    Here are pics of the new ones. Whadya think ?



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