Aviation fuel

[kevsled59]

I own an 08 D7 and last spring for summer storage I siphoned all the gasoline out of the tank and put in 2 gallons of aviation fuel. This winter I topped off the sled with gasoline which mixed with the Afuel. I went for 5 mile ride and the sled seemed to run good. ( sled has 400 miles) I cracked the throttle wide open and it got up to 60 mph then bogged. I was told that the aviation fuel has die and is not good for the motor. Should I siphon all the gas out and start over? I did change the plugs and haven't had a chance to ride it again due to conditions. Could the bog be coming from dirty exhaust valves?

 

[nine lives]

The first question would be, why run Afuel? Unless your sled is modified to the point of needing a different fuel to take advantage of a higher compression engine, you should be running only what the manufacturer recommends. Remember, octane rating is simply a measure of a fuel's resistance to knocking, not a rating of power, cleanliness, energy content, or any other performance enhancing quality. Having said that, if your sled has only 400 miles and you only rode it for 5 miles this year, I doubt that the little bit of Afuel or dirty exhaust valves would cause your problem. However, certain snowmobiles that have variable timing will adjust the timing accordingly so as to not damage a motor that is trying to burn the wrong fuel, and you could be experiencing this. I bet removing all the Afuel and running it for a while will cure it.

 

[Sledbrain2]

My guess is that he used the AV gas for storage because it will not turn green like regular gas. I used AV gas for 2 seasons and never had any issues that I can think of. I did have my smart valves collapse (AC) but that was normal from what I found out. I run a 14 to 1 head, so at 1400 ft I need to run 100% av gas or 92 above 7000 ft. Instead of changing out the head to play here I just run enough octane.

 

[Wade]

Lots of people winterize with Av Gas, it won't gum up the carbs.

 

[Gettin2old]

What rating of aviation fuel? was it 100LL (100 octane low-lead) or 110LL
Why did I even ask? it shouldnlt make a difference.

the dyes used as identifiers in AV fuels are so little it only gives the fuel a slight coloration. it is not like off-road diesel that is nearly blood red.

I do know that 100 LL is a very light blue to verify that the fuel clerk did not fill up your reciprocating gasoline engine with Jet-A which is clear and almost the same as kerosene and will cause engine failure shortly after take-off.

You may have a "Smart Valve" in the tank hanging up, if they sit dry they can stick closed.

I always advocate a full tank of fuel for storage so condensation is minimized and stabil added, and the engine run so the stabilzer can get into the carbs/injectors too.

And then for fall prep, siphon out all the fuel from storage and run it in a 4-stroke to use it, and add fresh for the sled.

What did the plugs look like? are the clutches freshly serviced? Critter nest in the exhaust or intake?

 

[kevsled59]

Aviation Fuel

The clutches have been serviced. The plugs were very dark, probably from the fogging oil> I use Blue Marble oil. How tough is it get at the valve in the gas tank? It had 2 gallons of av gas in the tank all summer.