gas leaking tank vent

[matt]

I have seen gas under bike for a few days. It  looks like it is coming from vent hose. So I remove hose and replace even though not plugged but hard as rock by tank. Check t in line and not blocked. Put back together seemed good but probably a gallon of fuel. Went and added 2 1/2 gallons not full and yup gas again out of vent. So my question is I hooked my mighty vac put finger over vent hole at filler and cannot produce vac, is the line sealed good at breather hole that if I plug it I can make vac or did tube in tank get a hole?  Tank looks awesome inside no rust

Thanks matt

[3W-lonerider]

sounds to me that you have a pin hole in the vent tube that runs up threw the tank.. buddy of mine had the same problem, but his issue came from buying a bike that the whole inside of the gas tank was rusted. and the vent tube in the tank got a hole rusted threw it.

[Solorider]

Hi matt,

I have fixed several of these older Valk, Tanks.... seems every Valk I repair has a rusted tank. I normally take the tank off and dump the remaining fuel into my recycle bin to observe how much rust comes out of tank, Most of them fill a 4x5 bin about an inch or so with rust , The Valk tank has a tank vent that leads from under the tank up through the tank to a pin hole in the neck of the tank.
when the tank rusts it rusts this small breather pipe which then allows the fuel to enter the tube end leak to ground.

Fix :

At this point you need to put a liner inside your tank which I use KREEM tank liner combo kit" https://www.amazon.com/Kreem-Products-Fuel-Liner-Combo-Pak/dp/B001J0DHZK follow directions

After you do your liner kit pug off the small breather under your tank which go's to ground and buy a vented gas tank cap off an earlier model Honda many have same cap, which match the Valks cap but they are vented gas caps.

Easy repair, No leaks, No rust in tank,

PS  I always install a new petcock after I use the old one as a stopper for the thank liner

Check YOUTUBE  theirs a mechanic from Arkansas that shows you a step by step Kreem tank liner install ! He also mentions the vented gas cap match to the Valks   https://www.youtube.com/watch?v=ITyszhh4XHs

Follow this and your tank will as good as new !

Happy motoring

Solorider

[Lyle Laun]

Don't mean to hijack this thread but....Solorider do you have a part number or the exact model & year of the bike with the vented cap ?

Thanks
Lyle

[Hook#3287]

Don't mean to hijack this thread but....Solorider do you have a part number or the exact model & year of the bike with the vented cap ?

Thanks
Lyle

Don't see that as a hijack, it's on topic.

Doesn't that vent double as a over-fill drain?

If you plug it, you'd have to be even more careful when gassing up.

[Solorider]

Vented gas caps are made with multi chambers to avoid splash back. If that wasn't the case I would just do a straight drill hole to the key way and be done with it thus allowing the stock cap to breath!  but that then could cause splash back !

If vented gas caps leaked you would see a lot of law suits and fire balls rolling down the highway......These Valk matching vented caps came on many different bikes as shadow, Nighthawk, Ascot of a certain year but not all  !!!!  If you fine one of these vented caps the price from china would be around $20.00 with two keys ,aged around mid 80s ...If you want to do your homework go for it !

The one Matching cap that I know is vented yet is a 100% match to the valks all years is the VF700C V45 Magna : 1982-1983. 1988   Ebay  $80.00

All these older Valkyries breather tubes are either already rusted through or going to rust through !  With the new Ethanol fuels, if you leave them sitting for any time they will rust ! 

This situation is the same with all bikes today....The other day my bud brought his 97 Harley by for me to look at ...his fuel tank had pin holes through it and was filled with rust !!!! The dealer told him he needed a new tank .... I repaired it with a tank liner and saved him thousands ....being he had a custom paint job and all.

One thing about tank liners is you have to give them time to dry.....weeks !!!! is the secret....if not they will not hold up...other then that they remind me of a Teflon coating in your tank .....and resist all types of fuels !!!!!  NO MoRE RUST


Keep the rubber down

Solorider
 

[Skinhead]

Could you not thread a piece of fishing line or wire coated with oil or WD40, into the vent tube prior to sealing, and then pull it out after to retain normal vent tube function?   I could see this not being an option if the Nipple where the hose attaches is rusted away, but should work otherwise.  Even if you can't remove the wire after treatment, you could still then go with a vented cap.  Just thought it would be worth a try.

[Solorider]

Wire through vent tube ???

 Maybe I was not clear , Sorry.....the vent tube go's up into the gas tank, and that tube is a thin bare metal tube which rusts away"""" LEAVING A GAP"""" ...you can test that by putting air compressor onto to bottom tube and hear where the air exits ( normally half way up the tank when rusted out** internally** )  normally that tube exits a pin hole in the neck of the gas tank filler hole.....If air exits there No problem **** Add a tank liner before it rusts out******
So when you fill your tank the gas enters that rusted out tube and just leaks to ground,...

It causes that mo-shine to get half the gas mileage that it would normally would ! Being half your gas just leaks out through the rotted tube opening and leaks to ground !!!!

Main question I get :::: BOY WHY DOES MY GAS MILEAGE SUCK ????????????? duhhhhhhh  Time to make some money !!!!!!

That tube breather is shot at that point !   Normal Valkyrie caps are NON-Vented 

SO PLUG TUBE FROM BOTTOM of the TANK ( J B weld ) AND BUY A VENTED CAP ((((( SIMPLE ))))))
OR BUY A NEW TANK with your paint scheme $$$$$$$$ ((((SIMPLE ))))

Solorider

 

[Skinhead]

Maybe I wasn't clear.   I fully understand the problem.  My suggestion of adding the wire through the vent tube prior to sealing the tank, would be the same as using a core during a casting process to create a void.  Once the tank, and the leaking vent tube, are sealed, pulling the wire out would, create a tube in the now sealed vent tube and ther would be no need to replace or drill the cap.  I've never tried this since I would  never let my equipment get in this condition.  If it ever did, I would sure give it a try.   Is that clear now?

[matt]

Let me say I scoped out tank after letting it dry out. Tank is very clean I do not see any rust. I cannot get good enough angles to see all of vent pipe but man its clean. But I guess no one has their tank off to answer my question. If you plug hole by cap and try to pull vac with mighty vac is tube sealed to tank good enough to do that?


If I seal up inside of tank was going to go to craft store and pick up (they look like pipe cleaners but longer) and put that in be while I try and seal.

[Lyle Laun]

Looks like this is the part number for the vented gas cap
17620-MB1-033

Regards
Lyle