race fuel

thats a good point, stations get busted all the time for wrong octane or bad quality...not often enough tho...ive been able to get good tuning with close to stock jetting with my stuff with ethanol 93, but i want to go to the next level. would be nice to advance my timing back to stock levels..

Don't forget when you pump your non-ethanol gas, from a mixing pump with multiple grades including 87 and 89 with ethanol.... to pump some in your car or truck first. What comes out of the pump first, is what the previous customer pumped. I've also been told that ethanol is added to the gasoline at the distribution point. It is just eyeballed by the driver not metered, so it can really vary. Local shop did head mod and cylinder porting, on a KTM 300 2T. Owner could not get it running right and blamed the shop's work. They asked for a fuel sample and tested it.... 26% ethanol.

In NY all the County Weights and Measures Supervisors care about, is how accurate the pump dispenses in gallons and tenths. They are not worried about the grade of fuel....

There are a couple of different issues getting mixed up here.

1. Air cooled bikes have a totally different set of problems because their cooling is "passive" and there is no upper limit on the temperature the top end can get to. Air cooled engines are much more effected by the quality of the fuel and its burn rate. They have much less "head room" for extra heat and they can get extremely high cylinder heat temps without any obvious indication until its too late. As a result the fuel quality is more important for them and it is really almost totally a reliability issue instead of a performance issue. You are not really looking for more power as much as lowering cylinder head temps and preventing/limiting detonation.

2. water cooled two strokes have active cooling (if it is not a thermal flow pumpless system) and they have an upper limit to cylinder head heat in the sense that the coolant will boil at a certain point depending on system pressure and volume. That is not to say they wont also run better with higher quality fuel, but its not nearly as critical as an air cooled engine.

3. modern FI four strokes are a whole different story in many ways. You can control every aspect of the fuel and ignition map, so they can take advantage of higher quality fuel purely for a performance gain and not reliability without ever opening up the engine, although to get the most gains, you will have to do internal mods.

For the majority of the bikes in the Vintage/Left Kicker section, even the LCs, you are going to be using race fuel predominantly for reliability reasons, and because of that (in my opinion) you are only looking to get enough octane to put you in the safe zone of 98-100 octane. The easiest/cheapest way to do that is a mix of plain jane leaded 110 race fuel and any non-ethanol pump, even 89 or 90 is fine because the leaded fuel raises the pump octane much more than just averaging the two numbers together, for example, 1 gallon of 110 and 3 gallons of 89 doesnt get you 94.25 it gets you closer to 96-97 which is good enough for any LC bike.

I switched to vp 110 not long ago mainly just to try to get rid of a decel knock in my 79 250 and it worked. I put in the 87 and the 85 250 and really cant tell any difference except for the smell. I found it by calling the nearest distributor and they gave me the closest dealer to my location and it was 10 miles from me in a small automotive shop.

I agree with all your points but in #3. Modern FI 4 strokes are over 12:1 compression engines that are actually de-tuned to run on pump gas reliably so they can be sold all around the world where the best fuels might not be available. Since you have the compression and the cylinder head airflow why not take advantage by using good fuel and re-map to get reliable performance gains without changing hard parts. Most of the time this involves increasing the spark advance in the low and mid range and retarding the advance at high rpm while leaning the fuel out, combine that with a little more fuel from idle to 4k rpm which will decrease the chance of flame out and make the throttle less abrupt coming out of corners... it works very well with race fuel and could be a disaster with pump gas which is why they don't come set up that way from the factory.

Yup, thats what I meant in #3 when I said they could take advantage of better fuel without opening them up because you totally control the fuel and ignition map. However, there is still no substitute for even higher compression and hotter cams.

A LOCAL SHOP ONWER I KNOW BOUGHT A TEST KIT AND COLLECTED SAMPLES FROM A NUMBER OF STATIONS THE AMOUNT OF ANOL'S CAN VERY A LOT HE THEN PUT THE SAMPLES IN DATED GLASS JARS AND SET THEM ON THE PARTS COUNTER AND WATCHED AN WAITED TO SEE WHAT THE STUFF TURNED N2 OVER TIME FOR ALL TO SEE MOST CUSTOMERS GOT THE POINT THEY DRAIN THERE TANKS OR BUY AN ADDITIVE OR RACEGAS HE ALSO HAD A NEWS ARTICLE ABOUT THE POSSIBILITY OF A NEW OFFROAD GAS

Living in screwed-up California I have found it impossible to find ethanol free fuel for sale out of a pump ANYWHERE. Due to this I have been running VP brand VPR leaded fuel in all of my bikes, both 2 and 4 stroke with excellent results. VPR is around 100 octane, is sold in 5 gallon drums and costs around $11.00 per gallon. I don't mind paying that amount because I don't have to do a carb overhaul every time I want to ride one of my bikes.

I've been using the 100LL AV gas from our local airport because my local VP guy keeps jacking the price up. A dealer in CO had it in bulk and was selling it for $7.25 per gal, my local VP guy has gone from $8 to $8.50 so I tried our local airport and they get $5 for the 100AV LL The performance difference between VP110 and 100AV is little to none.

LL thats low lead right? my old diesel mech teacher advised against AVgas he owned a plane FAA certified to do machine work on airplane engines more for for cold but thin air and steady throttle setting

Mix AV gas with pump and it works great.

I used to use Avgas many years ago. But here in the UK it is getting harder to obtain without hassle. Plus the fact that it is a "slow burning" fuel designed for aircraft that have a max of around 3000 rpm.
I just buy a 20 litre (5 gallon) drum of 115 octane leaded race fuel. It is delivered, so I don't even have to break into a sweat to go and get it. I mix this at 20% with our UK 'Super' unleaded. This is around 97 Octane. I did this mainly for the old 73 CCM, as it did not like the lower octane fuel. The two strokes seem to love leaded fuel, and I have found they are much happier on it. As is the weed wacker (strimmer) and the lawn mower as I can never be bothered to fetch regular gas for them. Second hand Castrol R is also dribbled into the lawn mower fuel tank so I can have the "experience" whilst doing the meaningful chores !

Mix it 50/ 50... Non oxygenated fuel.......very important ! . Cleaner burn and with much lower operating cylinder temperatures offers improved performance. Better tuning too in my opinion based on the above as well. I have been running straight leaded VP in all of my vintage bikes with Jo issues for many years. The smell of race gas burning with a quality caster based oil can't be beat and is worth the price of admission....

before adding the race fuel mix, i had finally gotten the 430 close to running great. it was so rich on bottom and mid with stock jetting and stock pipe/silencer. adding the dynoport didnt really seem to want any changes.
now with my mix its back to being rich..maybe a tad more than it was all stock.
im currently running 50/50 pure 91/110vp 40:1 klotz super techniplate (as always). 14/52 gears
400 main
r0 needle jet
6dh20 needle on leanest clip
2.5 slide modified to 3.0 (gauged with drill bit)
40 pilot
airscrew 2 turns
1.6 btdc timing
this had the bike pretty close on ethanol 93..still had a very small amount of four stroking if i really pushed it way up top. now its rich again, four stroking easily up top and sluggish in the mid, taking effort and a tug on the bars to wheelie in the midrange. thinking i need the next leaner needle jet as i maxed out the needle, and the needle didnt seem awfully sensitive to position changes, and perhaps a proper 3.0 slide. im planning on a lectron for this bike so im not really excited about pulling the carb to install a needle jet or ordering a slide. i have a bunch of needle jets but of course the single q8 i have is quite bitched up.....i hate pulling the carb on the single shock bikes. or even messing with the needle. i always put the front tire on something about a foot high to get the needle to fall in..

i tried straight cam2 once 30 years ago in my LECTRONED 81 430 XC it made it rich makes since i guess if the gas as bad ass you dont need as much