Vacuum petcock - Good news

[Giblet]

I recently put a kit in my petcock to replace a malfunctioning diaphram. The new plunger must have stuck open because the tank got drained after I removed a float bowl drain plug to replace the o-ring, expecting fuel loss to be no more than what was in the bowl. Since I had used clear fuel line on the vacuum port I was able to see fuel a small amount of fuel being drawn through the vacuum line for the petcock & was advised that I might have a pin hole in the diaphram. I did work with the petcock and got it working correctly. I've run 2 tanks of gas through and have gotten 38.7 & 39.9 mpg running 65-70mph. Previously I was averaging 35-36 mpg. I'll see how the next few tanks go & report the results but I thought this might be good to pass on. Having said that, I have a Pingle valve coming and will likely have a fully functional vacuum petcock for sale cheap & soon .

[Giblet]

Brands

I've been alternating between Chevron & Diamond Shamrock. Chevron consistently delivers 35-37mpg & Diamond Shamrock (same 2 stations) delivers 37-39mpg. Now here is the kicker, I filled up at a Texaco in Royse City on my way to work this morning & got 36.7mpg out of the Chevron tank after 120.5 miles. I filled up at the Diamond Shamrock on my way in this afternoon & got 41.4 mpg out of the Texaco tank after 69.2 miles. Only had one tank @ 40mpg since I've had it. I'm going to try Texaco for a week & see what happens. I'm beginning to suspect all gasolines are not even close, much less equal. I'm doing my best to be consistent with cruising speed & acceleration patterns as I can. Running stock coils, wire & one range hotter NGK plugs. Also have a K&N air filter in a stock air box.

[duaneage]

Possible headwind in one direction?

[Clone]

From my neck of the woods, everything comes from the same refinery. Husky puts different additives into the fuel depending on which brand it is, Esso, Petro-can, Mohawk, etc..
So, I usually run Husky mid grade as it is mixed ethanol. My part for the environment.

[LW_Icarus]

I try to avoid ethanol diluted fuels as much as humanly possible. gasoline burns best at a 14.7:1 air/fuel ratio. alcohol is somewhere near 7:1, requiring twice as much alcohol to make the same power as gasoline.

if you are already fighting a slightly lean condition logic would say that ethanol would lean it further. this may be paranoia, but since I only use a little fuel, Im okay with using straight gasoline. I dont care so much in the car as its injected, runs on anything.

I do my part for the environment by driving a small car and a smaller bike. Im sure alot of you guys don't have any problems with ethanol in gas, Ive just avoided it since they started the practice.

[Giblet]

Possible headwind in one direction?

I've wondered about that too since my commute is east-west. Early mornings here have been 62F until today. Started out at 73-74F. Got 35mpg today but that was with well over 2/3 full of Chevron. I'm going to go a week at a time on each station to rule out mixing results. I'd never have put this much effort into a science project back in my school days . If I can figure out how to get38-40 on every gallon I'll be happy.

[Giblet]

After installing a new Pingle fuel valve my GK is averaging 40mpg and stopped fowling the #2 plug. Apparently the problem was gas getting sucked down the vacuum line even after installing a petcock kit, so, apparently gas brand had nothing to do with it.

[SqDancerLynn1]

Personally I go to the station with the cheapest price. My new van probably gets 12-14 mpg I don't care I only drive it maybe 50 miles a week, I don't commute

[Giblet]

I've always been obsessive about my gas mileage no matter what I drive. When gas mileage starts fluctuating like that I want to know why.

[IanFrancisco]

I went from averaging 57mpg using 87 octane to averaging 60mpg using 89 octane, plus the bike runs better and has more power. Also, it seems to like Gumout fuel additive periodically. I've heard of guys running 1 or 2 oz. of two-stroke oil to a tank periodically to prevent corrosion of the exhausts. This was reported by a UK guy who has to ride in the corrosive rain over there. Slightly OT I know but I though I'd throw that in here.

[Giblet]

I'm looking at an 80 something XL600 a buddy has. Just waiting on him to tell me what he wants for it.

[IanFrancisco]

Some guys like those better than the current XR650L. A little shorter and almost as much power. You might need a bigger tank as the range is only 90-100 miles with the stocker.