Fuel and AV Gas

[kim]

Last weekend I forgot my fuel drum and had to borrow some gas of my mate.
As he uses AV Gas I wasn’t sure how it would go.
The first tank was about 50% AV Gas and ordinary pump gas.

Bike started and idled much better than normal.

Second tank was straight AV Gas and was running very rich, but idled and started excellent.

However I could really only use the first 1/8 of the throttle as it would start to splutter badly. Still had a good day riding, just had keep hooking up in higher gears.

WFO seemed OK, but it took some effort to get if up there.

Since I got home I have changed the pilot down from 45 to 42 and its now 40.
It starts and idles much better than it used to.
Air screw seems to have much less effect than it uses to.

Here is the question:
When running AV Gas would you expect to change your jetting significantly ?
And would you expect to go leaner all the way ?

As I have just found out I can get AV gas for the same price as super thru work and the airport is only 2km away, which have a 24-hrs fuel bousser.

With the idleing and starting alone it seems very worth it to change to AV Gas

Also I run 2% mix.

Any comments most welcome on AV Gas.

K

 

[iajim]

Av Gas

You might want to be very, very careful about running aircraft fuel in anything else. The octane numbers/ rating are different because a refinery lab uses a completely different engine for testing the fuels. Aircraft fuel also uses de- icers that automobile fuels don't, although with the use of ethanol and E 85, that isn't the big problem it used to be. Av gas will have a much different vapor pressure than gasoline. Conventional gas runs anywhere from 8.2 up to 9.5 (ballpark figures) . Av gas will be much lower at sea level, then in the higher altitudes and lower air pressures it would become more comparable to gasoline. It becomes easier for the fuel to turn to a vapor.
By way of comparison , water will boil at about 185 degrees F at 10,000 ft. Altitude has just as great an impact on fuel as water, lower pressure equals lower temperatures.
Av gas will give you more consistent jetting largely because gasoline has summer and winter , and here in Minnesota, intermediate blends. Winter gas has a higher vapor press. Summer will be at the low end and intermediate ,obviously in the middle. In very cold climates, butane is sometimes added to bump up the vapor pressure since cold weather tries to condense the pressure. If you have more butane then an adjustment needs to be made with the blending , usually cutting the hi octane platformate, reformate, full range "crack" (this is the liquid coming from the catalitic cracker unit of the refinery). I know you think I giving you a "snow job " with the tech . terms, but these are common to almost all refineries. All these variables are what drive people crazy when re jetting, however you' re re- jetting with something that's made your bike not something made for a Cessna.
When lead was phased out of gasoline many years ago, some refiners switched to using Manganese, I don't know if this has continued until now,but the point is, av gas and auto gas are two COMPLETELY DIFFERENT products.
Av gas does have higher octane ratings , so it probably feels as though your bike has a little more crispness in the response, and Av gas can be made to work , it will just take more trial and error tuning. For all the potential problems, you might be just as well off to run 50/50 blend of race fuel. You'd have a slightly higher octane rating, correct vapor press.and the summer /winter/ intermediate variables would be cut in half.
And now that everyone thinks I've been sniffing too much of that gas for my own good; I started working in the oil industry in 1979, Houston, Tx. propane/butane gas plant, tank farm & pipeline. 3 years laboratory, testing samples, 10 years operating units, Hydrogen reformer, desulfurizer,gas/oil reactor, amine contactors, etc. I've been out of the petroleum industry for almost a year now (and no, I don't miss it at all) but I learned enough in 27 plus years to speak with some conviction and truthfullness about these matters. If you want to run Av gas , you can , just be aware of all the potential problems.

 

[kim]

iajim

Awesome write up. Thanks a lot.

I have spoken to a number of local people and most of them say they are using a mix of BP racegas (octane 100) and normal gas (Octane 93). They don't know why thou ?, but I guess somebody told them to.

The biggest issue is that everybody seems knows a little bit, but nobody knows enough.....

Man, the bike was just so easy to start. First kick after taking the bike of the truck, after lunch etc. I want that back....

Kim

 

[Brian VT]

They always seem to run best just before they grenade. (LOLJK)

 

[skid jackson]

iajim


I have spoken to a number of local people and most of them say they are using a mix of BP racegas (octane 100) and normal gas (Octane 93). They don't know why thou ?,
Kim

lot of guys do that in my area ....2 reasons

1. it makes the bike run better

2. Economics, it's simply a way to stretch out the expensive race gas.

I have to run 50/50 in my trials bike to get it to run right. So I run 50/50 in the gasser, because well ... I got it!!

 

[iajim]

av gas

To Kim and other Gas Gassers, I hope I didn't run on too much with the techno- babble on gasoline. I just don't want to see anyone ruin a piston/ cylinder for the sake of half an octane number. I'm sure that somewhere, some one has a 1979 Yamaha, Kawasaki or Moto Guzzi that runs like a million on Av gas. Most fuel today isn't that great and just about any dirt bike is hi-performance enough to benefit from higher octane. My apologies if " I stepped on anyones toes". I try to limit my opinions and stick to the known qualities of petroleum. I noticed you're from New Zealand, I've never been in that area of the world, but I do pickup Trail bike Adventure Magazine. It looks like you've got some of the most spectacular riding "down there", and a lot of it appears to be exactly what Gas Gas riders' like. Have a good ride for me.

 

[kim]

To me its refreshing when somebody who has great knowledge actually takes the time and puts the facts on "paper".
If I can't understand the stuff, then I have an issue and needs to educate myself.

Hanging around this forum for a little while, one actually finds that there is very little the "group" doesn't know collectively and people are just sooo friendly here.

Riding is pretty good here with heaps of variety and not very far to drive for it.
Also the trail riding scene is quite large with lots of rural school using a trail ride as a fund raiser.
Often they can raise $6-8000 in a day. ie 3-400 riders at $20 per head and for that you often get the best country lunch and a 100km loop on private station land. Pretty good day out.

 

[SpeedyManiac]

I used to run 100LL AV gas in my EC200. The bike was jetted for it and ran perfectly. I've since switched back to 94 octane pump gas because it was a pain to get the 100LL, but I must say the bike ran a little better on 100LL. It wasn't necessarily making any more power, but it started easily, idled more consistently and ran a little cooler on AV gas. Just my thoughts.

 

[RBD]

I used to run 100LL AV gas in my EC200. The bike was jetted for it and ran perfectly. I've since switched back to 94 octane pump gas because it was a pain to get the 100LL, but I must say the bike ran a little better on 100LL. It wasn't necessarily making any more power, but it started easily, idled more consistently and ran a little cooler on AV gas. Just my thoughts.

Yep! Two Strokes sure do like their lead

And here is a great brew to try;

4Gal AV gas (100LL)
1 Gal Toluene
28 cc K1 Kerosene
And your Pre Mix at the ratio you usually use.

Ron

 

[skid jackson]

Yep! Two Strokes sure do like their lead

And here is a great brew to try;

4Gal AV gas (100LL)
1 Gal Toluene
28 cc K1 Kerosene
And your Pre Mix at the ratio you usually use.

Ron

Home Brew Gas!!!

 

[kim]

What does the Kerosene do in the mix ?

Whats the shelf life of Toulene ?

Kim

 

[RBD]

What does the Kerosene do in the mix ?

Whats the shelf life of Toulene ?

Kim

Toluene has a pretty good self life (it's a highly refined paint thinner). The K1 Kerosene is to counter act the washing effect that the Toluene produces.

Ron

 

[GMP]

Next time your in a bike shop, grab a bottle of octane booster and read the contents.

Ron,

What, if anything, can be added to pump gas the nullify the effects of ethanol, or more specificly the various percentages of ethanol to stabilize the mix for more consistancy?

 

[RBD]

Ron,

What, if anything, can be added to pump gas the nullify the effects of ethanol, or more specificly the various percentages of ethanol to stabilize the mix for more consistancy?

Hi Glenn,

I really do not know of any aditive that would counter act the ethanol problem. The only consistant fuels I know of, is the AV gas LL100 or race gas that comes in 55 gal drums.

Ron

 

[GMP]

I've always mixed various amounts of VP red with pump gas to equalize the seasonal blend changes here and minimize the jetting effects. At $8/gal though, an alternative would be nice.

 

[widebear]

Caster blend oils work well with alky based fuels since they are both organic, and as such should counter some of neg effects of alky content.

 

[GMP]

Too dirty, love the smell though.

 

[iajim]

Ethanol effects

If you're concerned about the 10% ethanol in gas, the best thing is to run 100% race fuel. I know its not cheap, you might find some non ethanol gas in more rural areas. I seems as though anywhere near a larger city every gas station sells only the 10% blend. The 100LL av gas w/ toulene & K1 sounds interesting, If memory serves me correctly I believe the 100 octane av gas is about 96- 98 octane when run thru a RON or MON engine. That would be more than enough for any stock compression engine. Perhaps you could check w/ some car clubs that specialize in 1960's muscle cars. Those vehicles werre engineered to run on HEAVILY leaded gas w/ no alcohol, see where they buy fuel. If all fails try the 50/50 race fuel blend, as long as you're not jetted on the edge of being too lean you'd have such a small amount of ethanol, it might not be such a big problem. Several years ago Moose Racing made some Alcohol kits (for people who couldn't get enough horsepower), you could contact them to see what changes were needed. I realize you don't want any alcohol in your fuel , just find out from them what can go wrong, prepare yourself for the worst, see what oil worked best w/ pure alcohol, etc. Might be worth a shot. Allow me to blow off my 'Brains', or lack of.The engines used in the refinery labs look about like a 4 hp Briggs & Stratton driven via belts by a 40- 50 hp elec. motor. Really!!! The elect. motor can be used to stabilize, increase/ decrease rpm. The cyl. heads are a flat head design and the head itself can be raised or lowered while the engine is running, hence the term Research Octane Number (RON) , timing is also adjusted on the fly, along w/ rpm. Motor Octane Number (MON) is much lower, the elect. motor can also be used to increase engine load(drag), and the timing is set at one point, and the cyl. head stays put. Granted , these engines are 4 cycle so they can run on fuel that would gag a 2 stroke. Just about any premium / hi octane fuel is going to work OK in a stock compression engine. If you're really concerned over it , add race fuel, some good quality octane booster, and don't skimp on the quality of the 2 cycle oil, happy trails to you.

 

[GMP]

My bike runs very well on pump gas, no need for race fuel from an octane perspective. Its just that the ethanol content varies seasonally, with more in winter blend fuel from Nov to April. This, along with cold, compound mixture changes. Race fuel blended in negates this change and keeps things more consistant.

 

[iancp5]

I think we're lucky in the UK. Pump gas (petrol) has plenty of octane and seems the same winter or summer although I have no idea if it actually is. Would drive me crazy if I had to rejet for winter, especially if never sure when and which stations have switched.