Race Gas - 110 Octane

[dodrt]

I have a 97 XR650L which has a Thumber Racing (TX) big bore kit, HRC Cam, K & N Air Filter and a FMF MegaMax Pipe. The bike seems to run better with the 110 than regular pump gas. Still I am nor sure if it worth the extra expense. Is 110 better for the motor, etc?

John - Wisconsin

[BWB63]

If it is leaded it helps a little, if your bike pings on pump fuel then it helps. Aviation fuel mixed 50/50 with pump fuel will help. Aviation fuel burns slower and drier. It is way cheaper then race fuel, I buy it at a local airport for $3.68 a gallon. It is 100 octane.

[hill5150]

I have AV Fuel in my pig 70/30 right now runs like a dream...real snappy

[flyin vee]

Used to run 50-50 av gas and regular in my MX bikes. I'm sure that will be more cost effective than the race fuel. If you have a local municipal airport the are pretty good to deal with to get the fuel. Hope this helps....OZ

[beezerjoe]

Usually if your compression ratio is 10:1 or less you can get away with pump gas.If it pings you need the good stuff.

[SX89]

It should run good on 91 to 93 pump gas unless the jetting is off, or you have a high comp piston.

Also even with a high comp piston tou should not need that high of octane.

And for the record AV gas has INCREDIABLY high amounts of lead which will lead to alot of deposits in your top end

My dads airplane always had alot of lead depostis at each annual (mandatory airplane Tech inspection) and it was designed and required AV gas.

Hope this might clear some things up for you.

[JohnnyAirtime]

If it is leaded it helps a little, if your bike pings on pump fuel then it helps. Aviation fuel mixed 50/50 with pump fuel will help. Aviation fuel burns slower and drier. It is way cheaper then race fuel, I buy it at a local airport for $3.68 a gallon. It is 100 octane.

You buying the LL100?

[JohnnyAirtime]

It should run good on 91 to 93 pump gas unless the jetting is off, or you have a high comp piston.

Also even with a high comp piston tou should not need that high of octane.

And for the record AV gas has INCREDIABLY high amounts of lead which will lead to alot of deposits in your top end

My dads airplane always had alot of lead depostis at each annual (mandatory airplane Tech inspection) and it was designed and required AV gas.

Hope this might clear some things up for you.

Marvel Mystery oil added to your fuel is supposed to take care of this. I wonder....

Seems like a lot of work to me. Running leaded fuels... high compression. When we have to... 80 octane in Mex is all we have.

If you can read through it... there's some good info here;

https://www.thumpertalk.com/forum/showthread.php?t=466693

.

[Denn10]

It should run good on 91 to 93 pump gas unless the jetting is off, or you have a high comp piston.

Also even with a high comp piston tou should not need that high of octane.

And for the record AV gas has INCREDIABLY high amounts of lead which will lead to alot of deposits in your top end

My dads airplane always had alot of lead depostis at each annual (mandatory airplane Tech inspection) and it was designed and required AV gas.

Hope this might clear some things up for you.

I worked for GA-ASI (makes Predator UAVs for AIR FORCE) as an engine builder and we used rotax aircraft engines and when we did our rebuilds there is alot of deposits from the av fuel so be careful i wouldnt run it in mine with all the cylinder heads and pistons ive had to clean But i am gonna try a little race fuel mixed with pump to see how it runs in my bike

[HawkGT]

....And for the record AV gas has INCREDIABLY high amounts of lead which will lead to alot of deposits in your top end...

Not really true. Practically speaking, 100LL is the only aviation gasoline available. It has a specification of a maximum 2.12 grams of lead per gallon. In the 1960s, leaded pump fuel had a maximum lead content of about 4.3 g/gal by law. The fifth addition of Modern Petroleum Technology suggests that most refiners' blends of premium gasoline actually contained between 2.6 and 3.0 grams per gallon. The EPA will tell you the same. By 1975 the maximum allowed amount was down to 1.7g. By the early eighties the rollout of unleaded gasolines was well underway and the leaded versions of pump gas that remained were down to 1.1 grams per gallon. The outright ban of leaded pump fuel didn't arrive until 1996; although by then it was exceptionally rare to find it anywhere.

Most leaded racing fuels will contain far more lead then 100LL. 4+ grams is typical (VP C12, for example contains 4.23 g/gal). The long defuct 100/130 blend of aviation gasoline (which was replaced by 100 Low Lead) had a max spec of about 4 g/gal.

My point is that 100LL does not contain "INCREDIABLY high amounts of lead" and actually contains less lead than most other leaded fuels that are available.

[rebelventurer]

I would reccomend using the unleaded race fuels, during a recent tear down of my yz250f I was amazed at how clean the top end was. After approximately 200hrs of use using the VP fuels MR-pro4 unleaded fuel, which is oxygenated and has an octane rating of 103, though very expensive. Here is a link for VP race fuels http://www.vpracingfuels.com/vp_01_fuels.html

On our small bore 2 strokes we use VP U4 which is a leaded fuel, but we have seen very little top end deposits, with it being mixed 50/50 with premium 93 octane pump gas.

In comparison there are other additives to prevent icing in av gas, I am unsure of the effects of these but do know most airplane motors are full of deposits after a year of service. But the lower price of this fuel compared to race gas would pay for a top end teardown, cleaning, and replacement parts.

Either way you are going to spend a lot more money running a modded motor over the stock will run on about anything motor.

Have you tried running premium unleaded from a quality station (chevron, shell) with a dose of 104 octane booster, its the only octane booster I reccomend most others contain MMT which is harmfull to most all the top end parts of your motor.

[HawkGT]

100LL rarely has any de-icing agents added during it's manufacture. They are added and used at the discretion of the end user. In some cases the supplier at the airport might add de-icing agents to all the 100LL they sell but I'd think that would be the exception rather than the rule. I know the 100LL available in my area DOES NOT contain any deicing agents.

One thing to remember about the vast majority of aircraft engines that use 100LL is they have manually operated fuel mixtures. There's a knob inside the cockpit the pilot uses to richen/lean the mixture during various phases of flight. Even the EFI systems that I'm aware of still leave it up to the pilot to determine rich or lean. From my experience in operating such engines, there's no way I would attribute engine deposites to fuel composition when the a/f mixture is so variable.

[crmc33]

I wouldnt bother running octane as high as 110 unless your running very high compression

Im running a 675 big bore with high compression head and this runs fine with 99RON unleaded (Shell V Power here in the UK)

Remeber that the higher the octane the slower the burn so you need more advance on the spark to get it to burn.

Im about to test an experimental CDI (on my XRL) with more advance and no rev limit so this will test the V-powers properties!

[HawkGT]

Octane rating says nothing about burn speed. Octane rating is ONLY a measure of detonation resistence--it says nothing about deflagration (burning) characteristics. You can have two fuels that demonstrate identical octane ratings yet have totally different burning characteristics.

FWIW, I've found the "high octane fuel burns slower" idea to be the most commonly cited--yet completely wrong--"fact" about gasoline. What I'm saying is I wouldn't blame anyone for thinking this is true because you here it so much. But make no mistake, it is a specious concept.

[gregman_1]

Try the oxygenated stuff...wheee!

[HeadTrauma]

Race gas is a complete waste of money if the engine doesn't need it. Too much octane can actually cost power.

[crmc33]

Yes, thats my experience too