Running airplane fuel in a 400f

The guy at the bike shop told me that the 400/426s run great on AV gas . Has anyone tried this if so what grade to you run? I know that there are several different grades. Which one works best and will this fuel cause any damage? THANKS Jim

I would love to try to use av gas in my bike. It is readily available at almost any airport, and cheap by comparison to VP stuff. Everyone says "don't run av gas, it's meant to run at altitude."

Well, let me say this. As a Private Pilot, I always use 100LL (Blue) in the Cessnas I fly. This is what I would use in the bike. My cross country flights are the ones that require the most altitude. About 5000 feet. Normally, a cessna is operated between 1500 and 3500 AGL (above ground level). NOW, some people that ride, live in areas that are 1500-3500 Mean Sea Level. SO, guess what, you're AT altitude. Also, a plane needs the most power when it is on the ground, preparing for takeoff roll...if the gas was only meant to be used at altitude....why would they use it at such low altitudes, when it should need to be operating the BEST?

I just run standard pump gas because it's cheap, if I wanted anyting else, i'll buy AvGas, not race fuel.


'01 KTM 520 SX

'95 KX 250 FOR SALE!!! -asking $2000 with decent amount of plastics/decals, parts!!

AMA Dist 6 Member

Hare Scramble Class B #523

100ll is leaded..ll stands low lead. I worked as an A&P for a few years and have heard/seen valve problems with the local hot rod guys running 100ll in their street rods after some time. The 100ll was blamed for lead build-up. I dont know if the 426 would develop these types of problems...Personally, I would use either pump gas or race gas formulated for bikes.

Also, Avgas is made to resist boiling at higher altitude (vapor lock)..but as Chris said, airplanes run fine when flying low and on the ground (but on the base leg in the pattern you always turn on the eletric fuel pump to prevent vapor lock). So who knows? Maybe the amount of lead in 100ll is so small that it wouldnt affect a bike engine. If you try it, let us know the results. By the way, in New Jersey, the Sunonco stations sell 94 ultra.. its a few cents more a gallon, but it seems to work great in the 426.


bottom line, its AVGAS, designed to run in airplane motors, the 426 is an ulta high- rev motor w/boocoo compression, i would stick with race gas.....



2001 yz 426

1998 gsx-r 750

I hate to stray off the original topic, but damn, Im jealous of you guys that can get pump gas higher than 91 octane. In So. Cal. it seems to go down a little bit every six months! confused.gif

Yeah what's with them lowering the octane all the time around here?



"What's that?"

"It's a Yellow 99' YZ400!!"

Hey-just to let everybody know I ran 100LL in my '00 426 for about 8 months. I recently had the engine tore down at a shop and the mechanic said everything looked good inside of it. The only problem he could see from running it was that the plug was gummed up a little from the lead. However most race gas that is used is also leaded and you have to change your plugs more frequently. So I really can't see a problem with running avgas, especially if you don't need the performance of race gas but want something a little better than pump gas. My bike definately ran better with it but I have since switched to 110 sonoco gas. If you can afford 4.50 a gallon it is awesome. Just my $.02


So Cal gas, don't understand, anyone have any info why? When I lived in VA it was 93. On my street bike, it ran great, then I moved back to great So Cal, and it was 92. Bike didn't run as nice, NOW IT IS 91, my bike runs like crap. SO I am goign to have to go to a booster or enhancer. I am running maxima octane booster in the 426. But may go to this enhancer. Here is the link for everyone to check out.

supposedly it gives alot more boost than octane boosters.And it is cheaper.

A coworker of mine just said is a myth that AV Gas is used for High altitude, low compression and low rpm's, so I would say not to use AV gas

From what I understand, CA gas is formulated very differently from gas that is available in the rest of the US. CA uses "special" additives that reduce particualte matter after combustion and have a lower volatility. MTBE should ring a bell. Also, alcohol is used in greater concentration than in normal gasoline. This special formulation is part of the reason that CA has higher prices at the pump and a big reason why bikes run like crap on CA gas!

As far as the octane rating, I have no idea why 91 is the upper limit in CA (as far as I have seen, anyway).

The altitude issue is not a myth with avgas (100ll). It has a lower (or higher) reids vapor rating..I cant remember..anyway its formulated to be more resistant to boiling (vapor lock in the fuel lines) than auto you increase altitude, pressure decreases along with the boiling point. Autogas will begin to boil at a lower altitude compared to avgas, this is why auto gas (mogas) isnt recommended for high altitude operation. Avgas works fine on the ground though. Granted this doesnt mean sh*t to a 426..Im just sharing what I know..Anyway back to the thread question, the manual doesn't recommend anything but premium pump gas..At the very least, you dont have to worry about hurting your engine running pump gas. If you do try the avgas, please report your results here. Sorry for the rambling...its slow here today and I really need to ride!


Wow, I never turn on the aux pump..Carbed 152 or Injected 172. Carb heat on base and final, but thats just for icing, obviously. Aux pump was considered a no-no when I was trained!

And RACE GAS HAS LEAD. Minute amounts, but it does have lead in it. I have heard this many times, infact, thats one of the reasons my uncles run it in the 2 strokes....the little bit of lead.


'01 KTM 520 SX

'95 KX 250 FOR SALE!!! -asking $2000 with decent amount of plastics/decals, parts!!

AMA Dist 6 Member

Hare Scramble Class B #523


This is off the thread subject...I suspect your instructor either owned the trainer or recieved his training by a cheap owner. Its a good idea to run the aux fuel pump on take-off and when entering the pattern, just as a safety precaution if the primary fuel pump craps out or as mentioned above, to prevent pump cavitation or vapor lock. I remember my instructor telling me to be sure I landed within a few feet of the threshold so I didnt have to use the brakes (He would say "these brakes cost alot of money"), if not he would insist that I do a go-around. He also would spout off about the aux pump and headlight costing money...Needless to say..after I finished my training and rented his planes solo, I would land long and stand on the brakes to even up all the extra money that I had spent in the past doing go-arounds. Anyway, just thought I could pass on some safety advice to a fellow pilot..By the way I just spoke with a guy that reads this board who fly lears out of NJ..he just bought a 426 and rides at Chatsworth...maybe we could all get together and rip sometime.

Mike the subject.

I trained at Harrisburg Jet Center, Capital City (Identifyer KCXY). It's a fairly good sized airport, right next to Harrisburg Inter'l. And Three Mile Island Nuclear plant. My instructor was a few years older than I am, and we rented from HJC, so he didn't own it. He trained in Colorado in an aviation school, like Embry Riddle - so it can't be cheap training. Who knows.

I'll check it out in the POH and and training info I have, see if there is anything written on the Aux pump subject. Hey, safety first when flying eh?!! I won't discredit ANYTHING that could save an accident.

OK, I'll stop posting off subject smile.gif

Just run Pump Gas, run a small octane booster if you desire. 93, California is weird, I saw that when we were out there. Aug 12th, I got 92 octane in LaMesa, Two days later, I could only get 91, same station.....I thought I was going crazy, seeing things, I guess not!

If you actually notice a difference in pump gas and race gas, what the heck are you still doing out of Ricky's semi?


'01 KTM 520 SX

'95 KX 250 FOR SALE!!! -asking $2000 with decent amount of plastics/decals, parts!!

AMA Dist 6 Member

Hare Scramble Class B #523

[This message has been edited by Chris Slade (edited October 20, 2001).]

SoundChaser, You can get Union 76 100 octane at the gas staion off of Cheseboro in Agoura. Its the pump on the far left as you pull in to the gas staion. Dan

I have been running 100LL in my 1999 400f. Have not had one problem. It seems to run a little better but the biggest thing I found is that it doesn't seem to stall as much with the 100LL.

Hello!!! Big compression needs high octane!

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