At what point is race gas better than 93 Premium?

[JustinBoots]

Is there a good rule of thumb when it comes to at what compression level race gas is beneficial? I've heard some say that anything less than 200PSI doesn't need race gas and then I see others on here using race gas in stock bikes because it keeps longer. I searched, but didn't find what I was looking for.

[don bassani]

Do not use pump fuel at all if it contains ethanol.

[JustinBoots]

All our fuel down here has up to 15% Ethanol in it, but our race organization has made it against the rules to use race fuel in our 50cc class. Was trying to figure out if I actually was missing out performance wise, but sounds like there might be a bigger reason.

[selbygirl]

try marinas some of them sell gas without ethanol or if you can find some one with a privet air strip for air plains , and i think its sunoco gas station some of them sell race gas or non ethanol gas just google sunoco . maryland has 2 stations deleware has 1 station so you may find one in your state .. or find a speed shop thats were we buy our gas they have 89 oct and up with no ethanol ,, ask them if you can run non ethanol gas since your running a 2 stroke , ethanol in a plastic gas tank gets milky and gummy and may mess up your reeds and carb

[nitrofish]

It is gettin' harder and harder around here just to find premium grade gas. Most of the stations have let those pumps run dry and put a bag over the handle. There is no real performance issue especially with stock or low compression motors, it has been argued that too high an octane can hurt performance on said engines. We run a quality race fuel because you can't find quality pump fuel anymore. Ethanol will destroy your engine in time, the higher percentages anyway. We lost about 23 chainsaws 2 years ago before we figured out the station had switched fuels and we discovered the culprit, high ethanol content. MW. Go to VPs site, they explain usages fairly well.

[selbygirl]

they had problems with boats around here the ethanol was clogging fuel lines and filters and was messing motors up , and some companys were voiding motor warrentys if you use more then 10% ehtanol . i would hate to be broke down 20 miles out in the ocean , some peaple use a water seperating filter seems to be helping a little bit

[mmsoup]

High Octane Race Gas burns slower and more evenly than lower octane formulations. Alcohol is a separate matter and when premixing can play havoc in jetting and other issues.
We have a couple of local stations in east tennessee that sell straight gas and IF I was mixing, I would use theirs.
If you are running higher compression heads, you need to move to higher octane numbers to reduce the possibility of detonation(Pre ignition)
110 will not perform as well as 93 in a 10.5:1 compression motor, but it is a requirement in a 14:1 motor to keep the motor together.

We run Malossi Big Bores and hot pipes in both of our kids quads and have slowly come to the realization that running straight 110 and oil mixed at 32:1 provides the safest power lubrication and engine cooling. I can run 110 mixed down 50/50 with 87 and get better power but run the risk of detonation, and I have the replate bills for proof.

[JustinBoots]

Thanks for all the info guys! Going to try and find some non-ethanol fuel options that are not considered race fuels. Who knows if I'll have any luck, but can't hurt to try.

[chunky0071]

We have a few series here not for minis but bigger bikes that don't allow race fuel but they do allow you to run fuel that is street legal. That is the ? I would ask we run VP100 AKA street blaze it is 100 octane oxygenated fuel that runs very well in these little motors and is street legal no lead.

[greenmachine70]

I work in the power equipment biz. Ethanol is evil. The company I work for is now the distributor for VP Racing's new fuel called SEF. It is a 94octane no ethanol fuel. You can get it in straight fuel or pre-mixed 40:1 & 50:1 and they actually use Motul oil. It is sold in quarts, 5g cans and 54g drums.
You can find it at many mower shops, it is going over well with the 2cycle chainsaw & handheld equipment.

[JustinBoots]

That's great to hear...I'll see if my local small engine repair shop can get it for me.

[machwon]

Originally posted by JustinBoots
Is there a good rule of thumb when it comes to at what compression level race gas is beneficial? I've heard some say that anything less than 200PSI doesn't need race gas and then I see others on here using race gas in stock bikes because it keeps longer. I searched, but didn't find what I was looking for.

justinboots, there really is no good rule of thumb for psi vs octane requirements. There are too many variables within a motor to accurately determine what psi goes with what fuel (unless someone knows most of the specifics). compression ratio, squish clearance are the main factors, but there are many others as well. A stock motor with stock porting and head may have 155 psi and run on 92 octane. The same motor with the exhaust port raised 2mm and a cut head may only have 140 psi, but yet require 100 octane. Basically the gauge can be fooled with a raised exhaust port as it doesn't have as long to get a higher gauge reading.

I recommend you use the minimum octane required by the engine manufacturer or as recommended by your engine builder. Thats the only way to be safe.

[JustinBoots]

Good to know....unfortunately I am running about 205PSI on a stock cylinder that has been ported so seems I'm the black sheep. :) Unless I'm checking PSI incorrectly, but I just kick it till it stops climbing.

[machwon]

You are correct by kicking until the guage stops, it also helps you have the throttle wide open. Gauges can be misleading too unless you have a good one. My hand held guage would show 200 psi while my snap on will show 155 on the same motor. 205 psi would be race fuel for sure, you may even have some survivability issues with a set up like that.

[JustinBoots]

My gauge set is I believe Motion Pro? Bought it for $100 from Motorcycle Superstore....after deciding the Equus one I bought from the the auto store was junk and only reading 110PSI