Belly tank volume

[MarkT]

 I have the standard tank, not the smaller one for Cobra exhaust.  I’m working on the fuel management system and want to verify it’s working as it should.  I filled the tank, then pumped the fuel into a gas can, and measured it by weight which was 15.75#, calculated the volume is 2.59 gal at 6.073lb / gal.  Is that about right?  I’m OK with the yield being less than 3 gal; I figure 2.59 is “nominally” 3, and there may be some overhead due to the fuel inlet location.  Just want to verify I don’t have a vent problem or the like.

Have you measured the usable fuel volume?  No info on that at R&M - they say it's a 3 gal tank.  Maybe it is but usable fuel may be less than 3.

I emailed an inquiry to Roger (he doesn't provide a phone on his site) but I can see why he might not want to answer if the answer is, I'm getting the correct volume when he advertises 3 gal. for this tank but "just over 2 1/2 gal for the smaller Cobra pipes-compatible tank". It's not a big deal to me, to have .41 gal less usable gas than advertised - it's still way better than the OEM tank volume w/o it.  I just want to know if I'm getting what I should or if I have an issue I can fix.

[WintrSol]

I've never measured it directly, but I have refilled with 6.8 gallons without having used reserve. So, main tank at 4.1 gallons, that makes 2.7 gallons or more in the belly. Was the bike or tank level, so the pickup was really at or near the bottom of the fuel?

[MarkT]

Looking at it now, I see the front of the tank is tapered and there's more clearance from the stock headers than necessary.  I'm thinking they sold me a Cobra type tank when I ordered the non-Cobra one.

The bike is level on my table lift - actually with the back lifted so the tire is not touching - if anything I am measuring MORE capacity then is available on the road, with the fuel pickup on the front of the tank.

Is your tank non-Cobra type?  Is there any taper on the sides, forward end?

Does your non-Cobra BT look like this?  From this angle - which we couldn't see without a smart phone and a high-lift scissors jack - doesn't look like too much clearance so maybe it's OK.  I'm back to thinking it may be a "nominal 3 gal" like a two by four is really 1 5/8 X 3 5/8.  Or I have some problem with venting or whatever but I checked that.

[WintrSol]

It's too dark and wet for photos now, but I felt the gaps between the headers and the tank. About 1 finger (just less than 1") clearance on the starboard side, and about two (maybe 1.5") on the port side, at the front of the tank.

[MarkT]

Going by feel I get similar finger measurements to yours.  So maybe their advertising is rather "generous" to put it kindly - but not accurate.  It also appears, there's at least a gallon worth of space above the tank before it gets to the lower limit of the swingarm, that could have been used.  But I understand, running it close to the limits on a production kit would likely cause them support problems for those variant bikes that get into that space.  I could remove, cut my tank and weld in a band to lift the top but that would be a lot of effort to gain just a gallon or so.  I'll just live with my 7.89 gal of fuel rather than the 8.3 I was promised.

[WintrSol]

I didn't mount my tank, as the bike came with it, but is there some leeway in the fore/aft tilt? Maybe yours is mounted with the front lower, and there is air trapped at the top of the rear? Just a WAG.

[MarkT]

No, it's a tight fit.  There's really no adjustability and it's a challenge to get it mounted.  It has a vent but I don't know where the end of it goes inside.  I would guess they route it to the top.  But if not, that's one possibility to limit capacity.

I'll add, routing the tubing is probably the hardest part; it's really crowded in the small gap in front of the tank, especially if you add a lot of extra plumbing like I did.

BTW I found a high quality Viton check valve if you want to actually count on the belly tank preventing hydrolock.  It won't w/o a valve like this or a Dan-Marc.  Gas goes right through the pump when it's off.  This check valve has a one-pound cracking pressure which is the pressure needed to get it flowing in the right direction.  That means it has a pretty good spring holding the valve shut to prevent the backflow - no drips, leaks and guaranteed for that.  Made in the USA too. Viton is the gasket material that must be used in gas/ethanol fuel handling valves as it doesn't break down from the fuel. The belly tank pumps put out 3# consistently per Roger.

[R&MM]

Mark,  Just volume checked a tank and the total capacity of the standard tank is 3 gal. 10 oz.   With the vent on the right front of the tank and bike on kickstand, I would expect to get 3 gal in it with a small air gap in the top right corner of tank.  There will be a few ounces you won't get out of the bottom of the tank but probably don't want to since it likely will have garbage from your plumbing. 

If your pump flows fuel when it is off, it probably has junk in the checks (teflon tape should not be used on any fuel system).   If it still flows fuel when off you may want to take it up with Facet and school their engineers. 

Our phone numbers are on the installation manual sent with each tank and on our installation pdf file on our website.  If we don't answer our phone leave a message.  Due to the amount of robocalls and telemarketing calls we are reluctant to answer if we don't know the number.  Thank you

P.S Looking at your picture, your tank is a standard 3 gal tank.

[Hyde]

With a standard (non I/S) tank and the R&M tank I put 8 and 8.1 gallons in my setup on more than one occasion yesterday. That's about as scientific as I can give you unfortunately

[MarkT]

Mark,  Just volume checked a tank and the total capacity of the standard tank is 3 gal. 10 oz.   With the vent on the right front of the tank and bike on kickstand, I would expect to get 3 gal in it with a small air gap in the top right corner of tank.  There will be a few ounces you won't get out of the bottom of the tank but probably don't want to since it likely will have garbage from your plumbing.  

If your pump flows fuel when it is off, it probably has junk in the checks (teflon tape should not be used on any fuel system).   If it still flows fuel when off you may want to take it up with Facet and school their engineers.  

Our phone numbers are on the installation manual sent with each tank and on our installation pdf file on our website.  If we don't answer our phone leave a message.  Due to the amount of robocalls and telemarketing calls we are reluctant to answer if we don't know the number.  Thank you

P.S Looking at your picture, your tank is a standard 3 gal tank.

Thanks for responding Roger. And verifying mine is a 3 gal tank. It might hold 3 gal but it's delivering 2.59 by weight, when it quits pumping after being filled to the top - not including the volume inside the filler tube which I believe doesn't drain due to the closed solenoid above it. This is with the bike vertical on the table lift - don't know if tipping it matters. I suspect a careful measurement of your deliverable fuel will give you the same, Roger.  If the tank you measured is made the same as mine.  Right I don't necessarily want the dregs on the bottom of the tank. If I knew an easy way to clean it out I would.  Meaning w/o pulling the tank off the bike.  If the pump gets junk in it and that makes it leak - well that's a pump in normal use, w/o any filter before the pump other than whatever filter the gas stations use.  I have many times found sand in my petcocks so I know the fuel isn't clean.  So w/o a filter any belly tank user can expect his pump to behave like mine - leaks when it's off.  I now have a high quality Viton check valve with one lb cracking pressure rating, downstream of the pump, so I think now mine won't leak.  Unless the check valve gets blocked open with crud.  Maybe a periodic flush is in order.  However it's installed in a difficult place to pull it.