Race gas for RM250

[d36RM racer]

I have read that my 03 RM250 will run way better on race gas Im thinking of buying some. but is it worth it anyone have any experence with this stuff and does it really help

 

[Jeffro426]

Having tried several types in several different bikes i can tell you this...Unless your bike is pinging or had some motor work done, i wouldnt even bother with it...you would be better off saving your money for something else. The performance gains is miniscule at best.

 

[nitropimp]

I run VP C12 in my 500, but it is a race only bike. If the engine is not detonating on the gas you run now, my opinion is, don't change it. C12 from the local shop is $ 6.00/gallon, 91 octane pump gas is $2.15/gallon.
There is some good reading about race fuel & pump gas on this board. Can do a search to find it.

 

[mxracer2000]

I can tell you that when I bought my bike the seller had filled it with race gas and I was amazed at the way the bike just seemed to explode right through the powerband. Since switching to premium pump gas Ive noticed a signifigant difference. This was with an 03 RM250. Since my riding is all trail riding I decided not to go and spend the extra money on race fuel. The more I think about it though the more Im considering going out and getting some. Some people here might tell you different but my experience with this bike and race gas was very, very noticeable. (its still no slouch though on pump fuel)

 

[zookieman]

I have an rm250 2003. I try to run nothing but %50 race fuel (110 octane leaded) and %50 regular high octane pump gas. I cannot speak for anyone else, but when on long rides sometimes I have to fuel up at a gas station along the rout (with straight pump gas) and I instantly notice a diffrence. Throttle response is not as crisp. It just does not explode like it does with race fuel.

 

[Jeffro426]

Hey, if i was payin 6 bucks a gallon, i too would feel faster! Heres somethign to chew on...
http://www.rc51.org/fuel.htm

This has been proved several times over in MANY types of engines. Oxygenated Race Fuels on the other hand, do make more horsepower...but it comes at a VERY high pricetag.

 

[Rich Rohrich]

Hey, if i was payin 6 bucks a gallon, i too would feel faster! Heres somethign to chew on...
http://www.rc51.org/fuel.htm

This has been proved several times over in MANY types of engines. Oxygenated Race Fuels on the other hand, do make more horsepower...but it comes at a VERY high pricetag.

A quote from the link you posted :

1. Standard Race Fuel (VP C12, C14, Sunoco 104, 100LL AvGas even high octane pump gas 96 or 100) ran straight on a stock RC51 motor will actually lose horsepower.

I love these kinds of sweeping statements from streetbike guys with a dynojet and "all the answers" :rotfl:

The reason those fuels can make less horsepower in an RC51 is because the 90% temp, endpoint temp , and pretty much the whole distillation curve in general is wrong for a high speed small combustion chamber engine. They couldn't have picked a more inappropriate group of fuels to run in that engine. Had they bothered to test fuels specifically designed for a high speed four-stroke they would have seen something entirely different. Anyone care to take bets on whether or not they recalibrated the EFI system for every fuel in that test to ensure that the fuel curve was identical in all cases? :rotfl: The idea that any high octane fuel will automatically make less horsepower in an engine like the RC51 is ridiculous.

The same can hold true for some pump fuels. The reason that SOME 87 octane fuels can make more power in a high speed four-stroke has to do with the distillation temperatures of the various components. In most cases higher octane components in pump fuel tend to have higher distillation temperatures associated with them. If the distillation temperatures are too high for the application then the fuel can't be properly vaporized in the short time, and short intake tract distance available on a 10,000 rpm four-stroke. You can't burn fuel that you can't vaporize.
The same thing holds true on the 250Fs and CRFs. The temperatures at the upper end of the distillation curve on pump fuels are well above 350F, or about 100-200 degrees higher than they should be for our use. This isn't a problem on a closed loop EFI equipped street car with their long very hot intake tracts as they cruise down the highway at 2800 rpm, but it's a big issue for us. Regardless of what you have heard, fuels are very much application specific. The wrong fuel has the same basic effect as the wrong jetting. Two-strokes have a whole different set of requirements than four-strokes, and big bores like the CR500 have different requirements than a tweaked CR125.

Bottom line is engines are a system, if you change one thing it impacts the whole system. If you don't choose a fuel that is designed for your application and then jet specifically for that fuel you are just wasting your time and money. If you choose the correct fuel and jet for it you'll find it can be money well spent.

 

[500_boy]

I will be running High Octane Race Gas through my CR500 because I doubt I will be riding it a whole lot. I just have had better experience with even going from 87 octane to 94. Especially in smaller engines such as my quad, it just runs smoother and has a more crisp throttle. If I start riding the CR500 alot though, I might switch to regular high octane pump because I can imagine it would get quite pricey as those bikes have a demanding thirst lol.

 

[bedell99]

Don't confuse "Race gas" with "Race fuel". Race gas is higher octane so you can run higher compression, more ignition lead, etc. It resists pre ignition, burns slower, cooler. Race fuels are more volatile and make more horsepower by virtue of the fuel, and its additives alone.

Race gas and Race fuel are the same thing. There are benefits in using the "correct" gas for the application. A common myth is race gas burns coolers,slower and as you say is more volatile. Most race fuels most important aspects is to prevent detonation, which enables you to jet crisply and run a higher compression motor with the fear of blowing it up. Next is matching the distallation curve with your specific application. As Rich has stated many times before, using a fuel meant for a different application(AVGAS, Sunoco 110, CAM 2, VP red) can actually produce less horsepower because of its high endpoints. The fuel will not atomize correctly due to the short intact tracks and mostly likely end up out of your silencer as goop and unburned gas. Yes they will having a cooling effect on you engine, but this not because its "race gas" but the droplets of gas that did not atomize will cool the piston crown. There are so many myths about race gas, but if you do a search you can ride ton's of useful infomation on this site. My recomendation is use a good quality moto-specific gas(VP C-12, MR2, Phillips B32(TT111),33(TT114),35(TT101), Sunoco Sumpreme Unleaded 112, MX 114, M02X) All these fuels have nice distillation curves with lower end points, which will give you nice throttle response and complete combustion at the higher loads.

Erik

 

[Mainjet]

I still think people confuse exotic racing fuels with race gas. They think that the "Fuel" itself is going to boost their horsepower/performance. It's apparent when you read their posts. Providing an overly technical dissertation about the propertys of different gasolines to the uninitiated, doesn't do much to clear up the misconception.

 

[Rich Rohrich]

I still think people confuse exotic racing fuels with race gas. They think that the "Fuel" itself is going to boost their horsepower/performance. It's apparent when you read their posts. Providing an overly technical dissertation about the propertys of different gasolines to the uninitiated, doesn't do much to clear up the misconception.

Either does posting the load of inaccurate crap you shoveled into this thread. Misinformation no matter how simply worded is still MISINFORMATION, and isn't welcome in the forums here. Try www.dirtbike.com, I'm sure they would welcome your thoughts on the subject. :rotfl:

 

[Mainjet]

What inaccurate crap would that be? I'm not welcome in your little fifedom? Asking you to keep it simple?

 

[Rich Rohrich]

What inaccurate crap would that be?

Well if you really want to go down this road once again :

Don't confuse "Race gas" with "Race fuel".

They are simply two names for the same thing.

Race gas<snip> burns slower,

Wrong. If it won't upset your delicate sensibilities I'd be happy to explain why it's wrong.

cooler.

Wrong here too, and the offer to explain still applies.

Race fuels <snip> make more horsepower by virtue of the fuel, and its additives alone.

I don't even know where to begin with that bizzare jumble of words. :yikes:

I deleted your original post in the hopes that it would just go away and you wouldn't be subjected to people hammering you for posting silly crap out here, but you just couldn't leave it be. The funny thing is I thought I was doing you a favor and trying to protect you. Clearly that was a stupid idea on my part. :bang:

You are certainly welcome here but posts that parrot back the same bad info again and again are not .

 

[steve125]

LOL Rich, I wish I posted earlier what I was thinkin when I read some of this thread.

It was that you were headed here>>> :bang: happens every time.

So Mainjet or anyone, heres your chance to re-learn what race fuel is all about. Ask Rich and he will help, forget all the track BS about race fuel that you think is right. 9 times out of 10 its wrong.

there's your choice, you can suck it up and learn. Or leave as ignorant as when you arrived.

 

[jackdrinker]

I run 1.5 gallons of cam2 and 3.5 gallons of sunoco 93.
My bike runs great in the tight woods and it's jetted really crisp... but, most of all I LIKE THE WAY IT SMELLS!!!!
03'RM250

 

[zookieman]

Again. I have a 2003rm250 and I run %50 sunoco 110 %50 premium my bike runs great. Not to technical, but simple...

Just try some and see what you think. It will not disinigrate your bike.

 

[nephron]

You're thirsty. Take a glass, fill it half up with water. Now piss in it, filling it to the brim.

Who knows what mixing a spec fuel with plume tank sweat will do to the distillation curve, flamefront speed, droplet size, effect on leanness/richness.

From what I've read of Rich's comments, the 50/50 is okay to get you home if you've got bad detonation.

...personally, I wouldn't waste a beautiful, pure, carefully parced race fuel with that stuff. Hell, my pickup 'll barely run right on the stuff.

 

[MXSparx]

So your saying a 50/50 mix is not so good? As in the 50% pump gas being crap right? And this will actually dilute the properties of the race gas?
If the above is correct, see below....if its wrong splain more please.

When I had my engine rebuilt last winter/spring HDR took it up to a 265 set up for running a 50/50 mix of fuel (race and pump swill) my choice not theirs. I went that route to keep costs down (1/2 price as apposed to full race) and to be able to tune the engine more accurately, I couldn't never get the Cowasaki jet right on pump gas. I'm a slow rider so getting 100% usage out of the engine is not really a factor in the equation.
Am I just sticking my finger in my eye doing this or would the benefits of 100% race fuel out weight the dollars I'm pinching?

 

[a454elk]

I learned that race gas, fuel, when sitting for more than a couple of weeks in your bike gums the crap outta your carb and valves. Thanks, but I'll stick to the pump stuff, not up for the minor benefits and higher cost of race fuel with a stock engine. Instead I'll just go out and buy a full race anodized race oil filler plug. :)

 

[Mike's 2003 YZ250]

I never tried race gas in any of the bikes or quads that I have owned over the years, but if it needs it or wants it, I would gladly buy it and use it, the heck with how much it cost. Im not quite sure I understand though. Is it good or bad for the bike? It seems some think it can do damage to the motor? Is it one of those things where it does good for some bikes and bad for others? I would think since its race gas and its expensive, it should outperform pump gas, since these are motorcross bikes. Is that the wrong way to think? Oh one more question. Can you run all race gas in the bike meaning no pump gas mixed in or is that bad?? Lastly, at what ratio do you mix race gas and oil, same as you would pump gas?? I would like to try the race fuel if you guys say you definitely felt a difference. Thanks for anymore information you can tell me. Mike :cool:

 

[WillyM]

Race gas

I never tried race gas in any of the bikes or quads that I have owned over the years, but if it needs it or wants it, I would gladly buy it and use it, the heck with how much it cost. Im not quite sure I understand though. Is it good or bad for the bike? It seems some think it can do damage to the motor? Is it one of those things where it does good for some bikes and bad for others? I would think since its race gas and its expensive, it should outperform pump gas, since these are motorcross bikes. Is that the wrong way to think? Oh one more question. Can you run all race gas in the bike meaning no pump gas mixed in or is that bad?? Lastly, at what ratio do you mix race gas and oil, same as you would pump gas?? I would like to try the race fuel if you guys say you definitely felt a difference. Thanks for anymore information you can tell me. Mike :cool:

Do Not USE Race gas unless your bike's compression Demands it.
If you cut the head,Reshape the combustion chamber or any other head mod Then and almost only then will you NEED to run Race gas!!!!!

 

[Rich Rohrich]

Im not quite sure I understand though. Is it good or bad for the bike? It seems some think it can do damage to the motor?

Race fuel won't hurt the engine and it mixes the same way pump gas does. Whether or not you'll see any benefits depends on a lot of things, not the least of which is your willingness to jet the engine very sharp. Even in a stock engine it will give you the opportunity to really fine tune things, but if you don't take advantage of that it's not a good investment.

 

[Rich Rohrich]

Am I just sticking my finger in my eye doing this or would the benefits of 100% race fuel out weight the dollars I'm pinching?

Sparks - If Pete built the engine with enough compression, or made some other port timing changes it may need the 50% race gas to protect it from knock that would occur on straight pump fuel . If that's the case then it's wise to keep running it.

If you don't want to bother fiddling with the jetting to really sharpen things up then going to straight race gas isn't likely to benefit you.

The 50/50 method is a great way to protect a modified engine on a budget. It's not the optimum setup, but it's a good trouble free solution. :cool:

 

[Mike's 2003 YZ250]

Ok, thanks for the replies. So since my bike is 100% stock, I shouldnt use it. I should only use it if I start modifying the bike. I guess I was just under the impression that you should always use race gas, but you dont have to if you dont want to or cant afford to, and that 93 octane pump will do just fine as well. Im the type of guy that wants to do the proper thing so I know Im taking the best possible care of the bike and feeding it what it wants, the cost comes second. Like someone else said, I barely ride the bike, so the cost wouldnt really matter to me. I filled up my bike with gas in the beginning of February, and just recently ran out of gas on my street about 2 weeks ago, lol!! So it took me like 6 months to use up a tank of gas. :laugh: Mike :ride:

 

[marcusgunby]

Some models need race gas even when std-it just depends on how close to the tuning edge the company decided to go, a classic example is the post 2000 cr125-they need race gas just to live a week-however they are slow as well , just to add insult to injury.