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General Category => General Discussion => Topic started by: 73 sport on July 05, 2022, 08:14:13 PM

Title: Gas Cap Gasket.
Post by: 73 sport on July 05, 2022, 08:14:13 PM

        Can anyone here provide me with the dimensions of the gasket for the "Flip"type cap on the '73/'74 Sport. I've made several with varying dimensions but they still leak. Thanks in advance.

Title: Re: Gas Cap Gasket.
Post by: moto on July 06, 2022, 07:59:31 AM

If it is like the cap on my T3, there is a small screw in the center of the cap as you look at it from the bottom. Adjusting this changes the pressure on the gasket. Just in case you haven't tried that.

Moto

Title: Re: Gas Cap Gasket.
Post by: 73 sport on July 06, 2022, 09:05:07 AM

     Thanks for responding Mr. Moto. I understand the center screws functions. The original rubber gasket had decayed and deformed, it could not be  used for dimensional reference.

Title: Re: Gas Cap Gasket.
Post by: guzzista on July 06, 2022, 11:48:25 AM

There is an early and a later size. Early has wider diameter gasket. Will take  pics and measure both, post later

Title: Re: Gas Cap Gasket.
Post by: guzzista on July 06, 2022, 04:15:22 PM

(https://i.ibb.co/MMZht3Z/IMG-0764.jpg) (https://ibb.co/MMZht3Z)

2 pics (https://imgbb.com/)




(https://i.ibb.co/7CZWHgq/IMG-0766.jpg) (https://ibb.co/7CZWHgq)


 The early cap  ( mine is from a 1974  850T tank) as in first pic is flattish, seals on outer  edge. OD on seal is 72mm.
 Later cap protrudes out and seals on the tank filler mouth , seal OD  approx. 50mm. I say approx. because another same design cap on my California 1100 shows about 48mm OD on the seal/ gasket , (possibly due to age shrinking/ reaction to fuel ?

Title: Re: Gas Cap Gasket.
Post by: 73 sport on July 06, 2022, 05:11:06 PM

    Thank you Guzzista. Mine is your first pix. The other dimension I need is the thickness.  My problem was I made them too small, to seal on the inner neck diameter.

Title: Re: Gas Cap Gasket.
Post by: lazlokovacs on July 06, 2022, 05:28:19 PM

I have the exact same problem with the same early type cap

 :popcorn:

Title: Re: Gas Cap Gasket.
Post by: czakky82 on July 06, 2022, 05:55:35 PM

My early cap seal looks horrible but hasn’t leaked a bit…🤷‍♂️

Title: Re: Gas Cap Gasket.
Post by: cliffrod on July 06, 2022, 05:56:24 PM

The gasket on my V7 Sport (that’s been on my bike since at least 1978-79 so probably original) measured no more than 1.5mm thick a few minutes ago.  If it’s old and shrunken, it would probably be no more than 2mm thick when new.   It seals fine.  Date on neck tag is Dec 1972 iirc, so 1973 model bike.

Given the filler neck that’s in my tank, I’m trying to understand how your cap leaks.  Tank would have to be very full.  Even then, I would expect the thickness of the gasket has less to do with sealing than the tension of the spring that’s in my cap as long as the gasket was actually wide enough to cover what needs to be sealed. 

 

Title: Re: Gas Cap Gasket.
Post by: 73 sport on July 06, 2022, 06:29:13 PM

    Cliffrod, thanks for the thickness info. As I stated above, I made them too small in diameter. The gasket seals on the outer edge of the filler neck. A long long time ago, when I rode my bike, I rode obscure back roads and ones less travelled . When I tanked, it was to the top. Now my bike is a  hanger queen in my living room.