I fill mine up to the top ring in your picture just below the holes you put in. Always ride after filling, never let the bike sit with that much gas in the tank.Like you I have to fill it up slowly and let in go back down and then up until that top of the neck.Been working for me for 9 years.As far as milage I have a trike and get maybe 33-34 on a good day.Windy down to 30. Ken

sprt220 wrote:
I fill mine up to the top ring in your picture just below the holes you put in. Always ride after filling, never let the bike sit with that much gas in the tank.Like you I have to fill it up slowly and let in go back down and then up until that top of the neck.Been working for me for 9 years.As far as milage I have a trike and get maybe 33-34 on a good day.Windy down to 30. Ken

When I installed the side car on mine, 34 became the norm.

I fill to the bottom of the fill neck. On my King Sporty tank that is on somewhat of a rake it means when I take off fuel comes out of the cap vent...LOL. So its full.

I get between 40-50 depending on conditions and road. Only once have I been under 40 and I don't ride real careful but Im not stupid either.

MidnightRide wrote:
Ctkog wrote:
I have no problem filling my tank up the neck and I have not spiked it. What is the purpose of spiking when we have a fuel vent tube? I'll have to watch closer on my next fill. maybe I'm missing something.

FYI I found a really cool elevation map HERE: http://elevation.maplogs.com/

You know, you make a good point.

For me, once the fuel hit the bottom of the filler neck the neck would fill up quickly, then it would sink down into the tank, and then fill up again, down into the tank, and so on SEVERAL TIMES until I'd finally give up on it LOL. Apparently it just doesn't vent quick enough and maybe the long rubber vent tube under the tank has a sharp bend or kink in it. I have to pull the tank off again when my new cables get in so I'll check a little better next time I pull it off.

So here's what happened today with the new holes. I was down about a gallon so before heading out on this trip so I started filling it. Instead of stopping and then filling only the neck when it hit the bottom of the filler neck, it just kept rising. I was suspicious so I stopped to see if it was going to go back down into the tank, AND IT DIDN'T. It was continuing to fill as it probably should have been doing all along.

So I tried to take it up to the holes and that hose was running so fast that it overflowed the tank a bit. I couldn't get that nozzle to trickle. So I stopped at about 1/4" below the holes and went for a ride.

I wonder if the rollover valve might be what restricts the venting enough to slow down filling above the neck line. I checked, I thought maybe I was the only one that left the roll over valve OFF when I removed my AIS, but I didn't. It was there. So I'm expecting to see the same slow filling once I hit the neck. I had been stopping at the bottom of the neck because it never occurred to me I could fit more fuel in there.

I may be joining those of you who have done the spiking. I wouldn't mind faster fills and getting more gas in my tank.

Ctkog wrote:
I wonder if the rollover valve might be what restricts the venting enough to slow the fill down above the neck line. I checked, I thought maybe I was the only one that left the roll over valve OFF when I removed my AIS, but I didn't. It was there. So I'm expecting to see the same slow filling once I hit the neck. I had been stopping at the bottom of the neck because it never occurred to me I could fit more fuel in there.

I may be joining those of you who have done the spiking. I wouldn't mind faster fills and getting more gas in my tank.


More than likely, it is the size of the vent hose itself.
It's purpose is two-fold: one keeping the vapor space from pressuring up due to thermal expansion yet small enough bore to prevent overfilling the tank past the filler neck. The filler neck extends into the tank ensure a vapor space is maintained.
Thermal expansion in an non-vented tank that is shell full can lead to a catastrophic failure. The atmospheric vent should prevent tank failure but still might burp fuel out if you were to fill the tank past the filler neck and then park it in the sun.

If I get a 1/4 gal more in the tank, I figure I'll burn that by the time I get to the house. On the highway, I'll squeeze a little more in.

I'm not sure but maybe it could be the gas itself getting better mileage in higher elevations. When I went to the Ozark Mountain Gathering a few years ago, I noticed my Intruder was getting much better mileage while up in the mountains. I also then found out that the stations in the area sold gas, not an alcohol blend of 10-15%. And this was for all levels, not just the "super". Around here, there are a couple places that sell "gas" but they only sell it at the high level, and I have to go out near the lakes as these stations sell it for the boaters. (Alcohol, absorbs water, very bad for boats,,)

I've spiked both of my Roadies... My original would only fill to the bottom of the neck and bubble up if I tried to fill it further, after I spiked it I would put in another half gallon. That Road* was 100% original and depending on the roads I traveled in Florida I was pulling down 42 MPG highway, 40 around town and if I made the run up A1A @ 50MPH only, I could get 50 MPG...
Now the new Star came with Cobra Dragsters and was jetted for them. After picking up the bike in Florida and driving it back to Connecticut I was only getting 32-34 MPG (But everyone knew I was coming with those pipes...! ) After I had it a couple of weeks I put stock mufflers back on it, but drilled them out to stage two... My MPG jumped up to 40 but she is running so rich, I nearly gassed myself when I pull up to a light! I need to re-jet the carb...
Because I spiked the neck on the new Star I can fill it up, but the gauge still won't go all the way up. I only let the gauge go down a little past 1/4 and at that, I'm only able to put in, at the most 3.75 Gal... One day, I'm going to take a gallon container with me and see where I run out. On my run from Florida to Connecticut, I did run out of gas, (in Atlanta when the carb puked in stop and go 100 degree traffic!) But the low fuel light never came on and the gauge was still reading just under an eighth.

With my 2013 RSSS I never got over 40 mpg and that only when running under 75. I also punched out the filler tube and filled up halfway up the tube. On the occasion I wasn't paying attention I overfilled and gas will run out the overflow onto the pavement. There's an extra 1/2 gal you can squeeze in by punching out the tube. My range went from 120 miles to 140 before reserve.

StarCruiser06 wrote:
I've spiked both of my Roadies... My original would only fill to the bottom of the neck and bubble up if I tried to fill it further, after I spiked it I would put in another half gallon. That Road* was 100% original and depending on the roads I traveled in Florida I was pulling down 42 MPG highway, 40 around town and if I made the run up A1A @ 50MPH only, I could get 50 MPG...
Now the new Star came with Cobra Dragsters and was jetted for them. After picking up the bike in Florida and driving it back to Connecticut I was only getting 32-34 MPG (But everyone knew I was coming with those pipes...! ) After I had it a couple of weeks I put stock mufflers back on it, but drilled them out to stage two... My MPG jumped up to 40 but she is running so rich, I nearly gassed myself when I pull up to a light! I need to re-jet the carb...
Because I spiked the neck on the new Star I can fill it up, but the gauge still won't go all the way up. I only let the gauge go down a little past 1/4 and at that, I'm only able to put in, at the most 3.75 Gal... One day, I'm going to take a gallon container with me and see where I run out. On my run from Florida to Connecticut, I did run out of gas, (in Atlanta when the carb puked in stop and go 100 degree traffic!) But the low fuel light never came on and the gauge was still reading just under an eighth.

Sounds like your fuel light is either burnt out or the plug isn't making a good connection. The green plug rests under the rear of the tank near the front of the seat. It may be corroded if it's lived in those wet moist climates.

Did you switch to RESERVE when it ran out of gas that time? If so, and it didn't help, your reserve petcock inlet may be plugged or it's in-tank filter is plugged (both the main and reserve tubes in the tank have their own filters). When I pulled my petcock out to replace the gaskets I found that the filters on both tubes were half missing. They'd probably been sucked into the petcock and possibly ended up in the fuel filter itself (I never found them). If that happened on yours then the filter may be clogging your reserve petcock tube. It's really easy to pull off and check and I'd suggest replacing the internal gasket while you're at it.

Your gauge may be reading correctly with the problem being in your petcock. We have always put in at least 4+ gallons when running the tank after the fuel light comes on.

I ride an 08. I punched my neck near the top (steel punch, full fuel tank), and found that (at least in the heat) if I fill it right up, it will overflow once the bike is off the kickstand. I typically fill to the top of the "collar" at the base of the fill tube. Best mileage ever was 341 or 342 km to a tank, typical is 200-250km but I also usually fill at about 1/4 tank.

Dan