Leaking fuel cap

[Nomorefours]

Hi, All

New to this forum, and happy to find it!

I bought a 2004 V11 Lemans Corsa Nero late last summer, and I have really enjoyed a handful of rides on it so far.  Happily, the bike is in excellent condition, and runs very well, with just a couple of very minor issues...

1.  If I fill the gas tank all the way, fuel 'weeps' out of the fuel cap and ends up on my riding pants...not so nice.  Once it is lower than maybe 7/8 full, it no longer happens.  This does not seem related to pressurization; I think the fuel is literally sloshing against the cap and getting past it when the level is high enough.  The cap appears to function normally, BUT I have noticed there does not seem to be any 'rubber' seal.  The cap has a metal ring that is spring loaded, and when closed this metal ring presses against a raised cream-coloured plastic lip.  So it is metal against plastic, which does not seem like a great way to make a seal.

Today I found some parts schematics online, but the fuel cap is only shown as a complete assembly.  I cannot tell if there is a rubber ring missing on mine, or not.

Searching photos online has been pretty fruitless.  Can anyone tell me if there is supposed to be a rubber ring, probably attached to the steel ring on the cap itself, to make a proper seal?

I have searched this forum, and found a reference to 'removing the rubber grommet on the cap' to solve tank pressurization / depressurization issues.  Is it possible the former owner followed this advice, and would it be the same rubber ring I am wondering about?

If my only resolution is to never fill the bike more than 7/8 full I guess I could live with it, but I would rather just have the cap seal and function properly.

I also read about Oberon fuel caps, but could not find a specific part number or model (since their website does not list one for the V11 Guzzis).  I don't really want to spend that $$ anyhow, when I can probably find a rubber ring at my local salvage yard (presumably from a different bike).

2.  The bike has Mistral mufflers which look and sound fantastic, and as far as I know stock ECU and air box.  It runs well, but *occasionally* stumbles around 3 - 4000 rpm.  It is not consistent.  Most of the time it does not stumble, just sometimes...but when it does, it is always around the same rpms.  I have not been able to determine any other constancy like outdoor temperature, bike warmed up or not, or anything else.  It just seems to randomly stumble around 3k - 4k on steady throttle.

Any thoughts or comments related to the above, are most welcome!

Thanks,

 

Doug

 

[MartyNZ]

4 hours ago, Nomorefours said:

...fuel 'weeps' out of the fuel cap... I cannot tell if there is a rubber ring missing... 

Hello Doug,

My fuel cap has a rubber seal. See picture. The seal is 2.5mm thick, and when the cap is latched closed, it can be pushed down about 3mm and springs back when released.

It is worth checking that the little vent seal beside the main seal is in place too.

If the seal was removed to cure "tank suck", then you might want to make sure that drain hoses connected to two nipples under the tank are open, clear, and long enough to carry fuel and vapours away from the hot bits of the engine. 

Marty 

 

[footgoose]

welcome Doug. great bike great 'handle'. I am with you there! though I did just buy a triple.

[Lucky Phil]

If you want an aftermarket cap you can use an Aprilia RSV unit. If you need a new seal I'd buy some sheet Viton or FKM from a rubber supplier of the right thickness and make your own. I see as you said they dont list a separate number for the seal. If you put some bearing blue or even some white enamel paint which you can immediately remove after on the tank sealing ridge or seal and close the cap then open it and look for marking you will be able to tell if its the seal not contacting. 

If the seal is making good contact then I would disassemble the cap and look for a problem in the cap vent. It should vent through the cap and into the round rubber seal that engages the round flange inside the cap assembly surround. In theory any fuel that gets into the cap surround area should be drained by the drain hose thats hooked up to it but it may be getting overwhelmed by a leak or the cap itself may be leaking internally and just dumping fuel out the top.

Ciao 

[MartyNZ]

4 hours ago, Nomorefours said:

...It runs well, but *occasionally* stumbles around 3 - 4000 rpm. 

You could start with Docc's advice here: https://www.v11lemans.com/forums/index.php?/topic/19610-decent-tune-up/

There are other improvements, but this is step 1.

 

[Nomorefours]

Hi, All

Many thanks for the helpful comments, suggestions, and link to the tuning instructions.  Looks like I need to get some cables to be able to complete the tuning process.

Does anyone know where I can get the software that was referenced?

Thanks,

Doug

P.S.  Just for fun, here is a pic you might find interesting of an unusual bike I just purchased to hang from the (very tall) ceiling in my living room...let me know if you can figure out what it is!!!  :-)

[docc]

Hi, Doug! Big welcome!

To find the guzzidiag software, click the link MartyNZ posted above to the "Decent Tune-up" and scroll down to Step 3, click the guzzidiag link,  and then the guzzidiag link in that next thread that comes up, "Basic guzzidiag Tutorial." Download the version for your computer operating system directly from "Beard", the developer.

Posting images is another matter. There is a size limit to upload directly, so you can resize in various imaging software and post into the reply. If your image is hosted already, open your image there, right click on it and select "Copy Image Location" then paste that into your post.

Looking forward to seeing the mystery art-bike!

[Nomorefours]

Hmm.

Not sure why the image did not post...I made it smaller than 200kb...I will try again...

[Nomorefours]

Still didn't work, even though it appeared to upload ok...

OK, let's try this:

https://www.dropbox.com/s/ul17jogl1ctrby4/IMG_5087.jpg?dl=0

Cheers,

Doug

[Nomorefours]

More pics of the same bike in this folder:

https://www.dropbox.com/sh/aae9l7oi5jvfr6x/AABsvVoIazZ4cl9S84vPojcia?dl=0

Cheers,

Doug

[docc]

Interesting bike! Here's what it looks like clicking "Copy Image Location" and pasting into the reply:

[docc]

I love this "steampunk" or dieselpunk  stuff (I don't know the difference, but I know what I like!

[Nomorefours]

Thanks!

I cannot take any credit for this build; I bought it the way you see it.

Those screen / filter things on either side of the headlight are actually functional turn signals (LEDs are under the screens)...headlight / speedo is from a 1950s Ural. :-)

[footgoose]

interesting indeed. nice exercise in punkery. I'm still trying to figure out what it 'was'. engine looks newer than the frame. 500ish cc Honda?

the adjustable riser upper tree is a new one on me.

[docc]

1 minute ago, Nomorefours said:

Thanks!

I cannot take any credit for this build; I bought it the way you see it.

Those screen / filter things on either side of the headlight are actually functional turn signals (LEDs are under the screens)...headlight / speedo is from a 1950s Ural. :-)

I was thinking the "screen/filters things" are acetylene lamps. I was trying to figure out how to make acetylene "wink."

(@footgoose, the full image set in the posted drop box shows the donor at the end . . .)