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Post by Bozzy on May 9, 2019 16:29:57 GMT 1
Just replaced fuel cap with aftermarket billet one. After draining the tank of fuel after winter storage I noticed that opening the cap towards the end quite a bit of suction had built up you could hear the air rushing in and the fuel flow increase.
Now I am not sure if it was because I was down to the last cup full of fuel in the tank but does the tank have a breather pipe as per F2's ?
The existing cap was a key lock type which may have let some air in as the lock flap was broken. Not sure if design is for the 31k caps to have air inlet in the cap.?
Overall hoping that I will not have to drill a hole into a new expensive cap!.
Assume many have changed the fuel cap. Am I being too concerned?
Thanks for reply's
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Post by midlifecrisisrd on May 9, 2019 16:33:15 GMT 1
The cap does need to vent
The original vents through the keyhole
Steve
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Post by marrcel on May 9, 2019 16:34:52 GMT 1
31k vents through the cap. No breather pipe.
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Post by bazzer5115 on May 9, 2019 16:56:33 GMT 1
Had this with the after market billet spin on/spin off type.
Did a test with tank removed from bike,full of fuel with pipe going to Jerry can.
With the standard cap the fuel would give a good flow all the way,but with spin on/spin off type after about 15 seconds the flow started getting slower and slower.
Showing the cap was not venting well enough.
As I drive my bikes hard most of the time and on premix I was worried about it starting to run lean and seizing.
Bought an after market standard type from NORBO I believe.tested and all is good.
Beware of these type caps if you regularly thrash your bikes.👍
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Post by dusty350 on May 9, 2019 18:10:44 GMT 1
The bad news is you will need to drill a hole in the cap I'm afraid. I've had the same problem with the billet cap with the Yam logo in the middle. My bikes are kept in a warm garage, and each time I removed the cap there was a loud hiss, proving they weren't venting -I had 2 on different bikes - both the same. If you look beneath the rubber seal on the underside you will see a vent channel which is great until you tighten the rubber seal against it when you turn the cap closed !! I drilled a 3mm hole straight through the middle of the tuning fork logo; rdlccrazy.proboards.com/thread/37571/carbon-lc?page=12rdlccrazy.proboards.com/thread/37571/carbon-lc?page=13It's never spilled fuel through the hole, so it's ok, if a little tricky, to do. Never had a problem afterwards. Dusty  |
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Post by Bozzy on May 9, 2019 18:54:15 GMT 1
thanks for feedback looks like drilling time. better change it back for now to original
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Post by reggieperrin on May 10, 2019 8:38:51 GMT 1
The cap does need to vent The original vents through the keyhole Steve It bloody leaks through the keyhole as well..!!  I never fill the tank now as it pisses fuel out everywhere... would be great to find one that doesn't. |
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Post by JonW on May 10, 2019 9:05:19 GMT 1
Usually there is a small felt pad and a ball bearing as a valve isnt there? There has been in a number of the ones Ive opened up.
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