leaky petrol caps

mauricejota7604

mauricejota7604

Hero member
Location
Victoria Australia
Hi Hopefully someone out there will have an answer to this one, since completing my 3C I have never been able to completly seal the petrol filler cap, the best result I have is an anti suge rubber under the cap but no matter how much tweaking there is always a little petrol dribble onto the tank outer can someone tell me the way to adjust these fuel caps???????
Thanks,
M.
 
Hi Maurice... you can adjust the spring and clip a little, but if it's still leaking I suggest it's rooted. I've stuffed around with those things heaps. Make sure your tank itself doesn't have an unequal lip for the rubber to seat on..
But finally, Wolfgang will send one for not much $$..
HTH
Ian
 
They are well known for pissing petrol out Maurice. The only solution years ago was to not put much fuel in. This was easy because I had no money anyway  :D
 
I had the same problem with my 3CL. During my restoration I treated it to a shiny new cap but noticed it had a smaller seal but it protruded farther into the filler and sealed[tried to] on the dished portion of the neck. It almost worked,except when the tank was fullish. I ended up swapping the seal and spring,plate etc. out of the old cap and it works fine now. In other words,is your cap seal the 80mm dia. or the 40mm style? It should be the 80mm and the seal surface should rest on the raised bead around the edge of the filler.
 
chriskay said:
I thought they all leaked like that?
Click to expand...

I bought my '73 3c in early '74, with less than 2000 miles on it. The tank cap overflowed the first time I filled it to the top. All my mates with Ducatis and Guzzis with the same cap said theirs were the same. They leak.

Ken
 
Can't agree there Ken. Neither my Jota nor Monty leak..and I do fill them. Just a case of getting the cap and tank right in my view.. But hey, we all seem to have different experiences with these things.

8)
 
Not had many problems with this on the Jota 120. Then come MOT day the tester rode her off to the workshop and came back later saying the fuel filler was leaking out which was an MOT test fail. Shit!
Luckily I've been going there for years so he passed me on the promise I'd get it sorted asap. Off home I went and played around with the rubber seal and inserted the hard black plastic 'surge' thingamy into the tank. That cured the leaking, but on the 3rd fillup I noticed the black thingamy was missing so it must have pushed into the tank.
Damn and blast. I hope it won't deteriorate into a mush that will clog up the carbs.  :'(

Note to self. Remove it when next home.

DoC!
 
I must be extremely lucky,none of the caps on my three bevels leak and the 35 yr. old seal on the Lav is sealing just fine!
Of course writing this may jinx me forever.
 
Thanks all, now for the early triple owners should my petrol cap seal on the larger outer face instead of the recessed smaller diameter?? I had a look at a couple of SF caps and they dont are flat and dont have that inner smaller diameter seal .
The one on my bike is has the smaller inner seal and I am thinking it may not designed to seal in there??
M.
 
The seal that lives up to its name on my bike has an outer diameter of 80mm and it seals on the raised lip around the outer edge of the filler neck which is 74mm in diameter. This is on a 76 3CL. The smaller seal is 49mm in diameter which is raised about 6mm from the main body of the cap and doesn't quite do the job as it sits in the dished portion of the filler. Must be for something later or with a smaller filler hole.
 
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