Best Race Fuel for stock 250 2 stroke

1stSSPZ
Profile picture for user 1stSSPZ
Posts
257
Joined
3/17/2014
Location
Lubbock, TX, USA
1stSSPZ 1/1/2015 11:21am
1/1/2015 11:21am
I did not have to do any re-jetting on my YZ250. The best place around here to buy race fuel is at a hot rod shop, not a bike shop. I can get C12 for $73 for a 5 gal can.
Trav138
Profile picture for user Trav138
Posts
1477
Joined
3/8/2012
Location
USA
Trav138 1/1/2015 11:31am
1/1/2015 11:31am
JBernard_401 wrote:
had detonation in head after 10hr running 93 on my stock 14 ktm 250sx. put the 300sx kit on and been running vp110 straight ever since...
had detonation in head after 10hr running 93 on my stock 14 ktm 250sx. put the 300sx kit on and been running vp110 straight ever since. 8$ a gal.
the throttle response, jetting ease, predictability and lack of spooge is amazing.
I love VP 110 also. I agree on the jetting ease, made dialing in my RM much easier.
kx254f
Profile picture for user kx254f
Posts
290
Joined
7/15/2009
Location
Auburn, ME, USA
kx254f 1/1/2015 12:13pm
1/1/2015 12:13pm Edited Date/Time 1/1/2015 12:15pm
rippaaa wrote:
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas. What is the best race fuel to do this...
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas.

What is the best race fuel to do this with? would it be leaded and non oxygenated? and what is the best fuel for it (ex. klotz 110 etc)

For a stock 2013 KTM 250SX
A stock 250 doesn't really benefit a whole lot from running race fuel. It's actually a good way to waste money if you're putting too much in your mix. 50/50 sounds like way too much in my opinion. Without a dyno, you'll never really know if there's a performance increase.

It's all about the compression ratio as far as I understand. Higher compression ratios benefit from race fuels but each has a specific application. I'm no expert in this but this is what I've been doing for the last 5 years in my YZ125 and YZ250 with good results in both performance and longevity:

1.25 Gallons of VP110 or C12 mixed with 3.75 of 91 or 93 unleaded (ethanol free if possible) mixed with Amsoil Dominator 50:1. 50:1 with this particular premix is fine as long as you're super particular and make sure not a speck of dirt passes through your air filter or drops in your airboot upon removal. I always inspect with a flashlight and clean accordingly.
rippaaa
Profile picture for user rippaaa
Posts
366
Joined
11/22/2014
Location
CA
rippaaa 1/1/2015 12:27pm
1/1/2015 12:27pm
rippaaa wrote:
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas. What is the best race fuel to do this...
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas.

What is the best race fuel to do this with? would it be leaded and non oxygenated? and what is the best fuel for it (ex. klotz 110 etc)

For a stock 2013 KTM 250SX
kx254f wrote:
A stock 250 doesn't really benefit a whole lot from running race fuel. It's actually a good way to waste money if you're putting too much...
A stock 250 doesn't really benefit a whole lot from running race fuel. It's actually a good way to waste money if you're putting too much in your mix. 50/50 sounds like way too much in my opinion. Without a dyno, you'll never really know if there's a performance increase.

It's all about the compression ratio as far as I understand. Higher compression ratios benefit from race fuels but each has a specific application. I'm no expert in this but this is what I've been doing for the last 5 years in my YZ125 and YZ250 with good results in both performance and longevity:

1.25 Gallons of VP110 or C12 mixed with 3.75 of 91 or 93 unleaded (ethanol free if possible) mixed with Amsoil Dominator 50:1. 50:1 with this particular premix is fine as long as you're super particular and make sure not a speck of dirt passes through your air filter or drops in your airboot upon removal. I always inspect with a flashlight and clean accordingly.
Ethanol free is easy to get but unleaded? i hough leaded fuel was good for 2 smokers?

I decided on just to run pump fuel still

The Shop

See All »
kx254f
Profile picture for user kx254f
Posts
290
Joined
7/15/2009
Location
Auburn, ME, USA
kx254f 1/1/2015 12:44pm
1/1/2015 12:44pm
rippaaa wrote:
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas. What is the best race fuel to do this...
Hey, looking to run race fuel at a 50/50 mix with high octane ethanol free pump gas.

What is the best race fuel to do this with? would it be leaded and non oxygenated? and what is the best fuel for it (ex. klotz 110 etc)

For a stock 2013 KTM 250SX
kx254f wrote:
A stock 250 doesn't really benefit a whole lot from running race fuel. It's actually a good way to waste money if you're putting too much...
A stock 250 doesn't really benefit a whole lot from running race fuel. It's actually a good way to waste money if you're putting too much in your mix. 50/50 sounds like way too much in my opinion. Without a dyno, you'll never really know if there's a performance increase.

It's all about the compression ratio as far as I understand. Higher compression ratios benefit from race fuels but each has a specific application. I'm no expert in this but this is what I've been doing for the last 5 years in my YZ125 and YZ250 with good results in both performance and longevity:

1.25 Gallons of VP110 or C12 mixed with 3.75 of 91 or 93 unleaded (ethanol free if possible) mixed with Amsoil Dominator 50:1. 50:1 with this particular premix is fine as long as you're super particular and make sure not a speck of dirt passes through your air filter or drops in your airboot upon removal. I always inspect with a flashlight and clean accordingly.
rippaaa wrote:
Ethanol free is easy to get but unleaded? i hough leaded fuel was good for 2 smokers?

I decided on just to run pump fuel still
Most pump gas is unleaded for vehicle use.

Leaded is good for two strokes but 100% isn't necessary and is most likely harmful. Lead just helps with lubricity and reduces wear so I little is a good thing.
Dragoo168
Profile picture for user Dragoo168
Posts
239
Joined
4/14/2014
Location
USA
Dragoo168 1/1/2015 1:05pm
1/1/2015 1:05pm
As stated before, many are addressing the necessity based on detonation factors and compression requirements,...That's all good, but don't dismiss the gains of running quality fuel, and do not say that it is ever a waste of money, especially in a two-stroke, where the fuel as well as the oil is what washes, lubricates, and functions your engine, LOL! If it's not affordable, then don't sweat it, but if it is, then don't be cheap, and use it. Remember, it's the purity of the fuel that is the benefit, which affects runniing temps, jetting consistency, wear, as well as enhancing the qualities of the oil that you choose to mix with it Even if you mixed two-gallons of Premium to one gallon of Race fuel, there would be a benefit in the mix, simply because you're starting to dilute the additives that are completely unnecessary in your bike.
rcannon
Profile picture for user rcannon
Posts
357
Joined
2/11/2007
Location
West Jordan, UT, USA
rcannon 1/1/2015 1:20pm
1/1/2015 1:20pm Edited Date/Time 1/1/2015 1:22pm
Running race fuel in a stock yz 250 is a bad aid covering a poorly designed head. You can still run it after having this guy machine your head, but you dont need to. 100, for sure you should. It works better, and is better fuel, but if your going that far, why not spend an extra 75 bucks and really get some benefit from it?

http://www.rb-designs.com/rb_designs_llc_025.htm

Once you have the head modified, the bike will run better on pump premium, with ethanol, than it will on race gas and the stock head. A number 8 slide is nice, too.

Once the head is correct, the bike is easier to jet, and a lot more responsive. Its not about raising compression, or lowering. Its only about using exact dimensions.
nytsmaC
Profile picture for user nytsmaC
Posts
5946
Joined
8/10/2009
Location
Frig Off, CA
nytsmaC 1/1/2015 1:20pm
1/1/2015 1:20pm
nytsmaC wrote:
Renegade SX2, go up at least 2 sizes on the mainjet and you'll feel the difference. I've tried mixing C12 50/50 with premium non ethanol pump...
Renegade SX2, go up at least 2 sizes on the mainjet and you'll feel the difference. I've tried mixing C12 50/50 with premium non ethanol pump gas, the SX2 is worth it.
JW381 wrote:
Why do you suggest going up on the main?
It's oxygenated, like VP MR-2. More oxygen, more fuel, more power. It's very noticeable.
JW381
Profile picture for user JW381
Posts
10638
Joined
7/21/2009
Location
Harrisburg, OR, USA
JW381 1/1/2015 1:25pm
1/1/2015 1:25pm
nytsmaC wrote:
Renegade SX2, go up at least 2 sizes on the mainjet and you'll feel the difference. I've tried mixing C12 50/50 with premium non ethanol pump...
Renegade SX2, go up at least 2 sizes on the mainjet and you'll feel the difference. I've tried mixing C12 50/50 with premium non ethanol pump gas, the SX2 is worth it.
JW381 wrote:
Why do you suggest going up on the main?
nytsmaC wrote:
It's oxygenated, like VP MR-2. More oxygen, more fuel, more power. It's very noticeable.
Ah, gotcha. The race fuel I run isn't oxygenated, I dont believe, so I havent had to rejet. Do you guys get more overrev by bumping the main up one? Or is that just a goony urban myth.
sesker15
Profile picture for user sesker15
Posts
1054
Joined
4/14/2008
Location
Upper Marlboro, MD, USA
sesker15 1/1/2015 1:46pm
1/1/2015 1:46pm
New vp 2 stroke fuel that comes already mix with 2 stroke oil.

nytsmaC
Profile picture for user nytsmaC
Posts
5946
Joined
8/10/2009
Location
Frig Off, CA
nytsmaC 1/1/2015 5:43pm
1/1/2015 5:43pm
JW381 wrote:
Why do you suggest going up on the main?
nytsmaC wrote:
It's oxygenated, like VP MR-2. More oxygen, more fuel, more power. It's very noticeable.
JW381 wrote:
Ah, gotcha. The race fuel I run isn't oxygenated, I dont believe, so I havent had to rejet. Do you guys get more overrev by bumping...
Ah, gotcha. The race fuel I run isn't oxygenated, I dont believe, so I havent had to rejet. Do you guys get more overrev by bumping the main up one? Or is that just a goony urban myth.
Yes definitely a lot more overrev when you jet up with the oxygenated fuel, that is where I notice the biggest gains by far. The wngine keeps pulling where normally you'd be grabbing a gear, and just stronger in general. You will see these gains on a stock engine, doesn't need to be built for race fuel only.
JW381
Profile picture for user JW381
Posts
10638
Joined
7/21/2009
Location
Harrisburg, OR, USA
JW381 1/1/2015 5:46pm
1/1/2015 5:46pm
nytsmaC wrote:
It's oxygenated, like VP MR-2. More oxygen, more fuel, more power. It's very noticeable.
JW381 wrote:
Ah, gotcha. The race fuel I run isn't oxygenated, I dont believe, so I havent had to rejet. Do you guys get more overrev by bumping...
Ah, gotcha. The race fuel I run isn't oxygenated, I dont believe, so I havent had to rejet. Do you guys get more overrev by bumping the main up one? Or is that just a goony urban myth.
nytsmaC wrote:
Yes definitely a lot more overrev when you jet up with the oxygenated fuel, that is where I notice the biggest gains by far. The wngine...
Yes definitely a lot more overrev when you jet up with the oxygenated fuel, that is where I notice the biggest gains by far. The wngine keeps pulling where normally you'd be grabbing a gear, and just stronger in general. You will see these gains on a stock engine, doesn't need to be built for race fuel only.
I will have to try that. I have oxygenated 100LL at the pump. Will mix some of that and throw a 180 main in there. My Gorr motor is awesome, but I'd like it to pull longer.
nytsmaC
Profile picture for user nytsmaC
Posts
5946
Joined
8/10/2009
Location
Frig Off, CA
nytsmaC 1/1/2015 6:38pm
1/1/2015 6:38pm
GeorgiePorgie wrote:
What do you guys run in 144s?
I run the above in my 144 and have go between a 195 and 200 main with it, stock was a 190.

Give it a try Justin, what jetting are you using now? You may benefit from going bigger than a 180. I use a 190 in my 250 but stock was a 185.
JW381
Profile picture for user JW381
Posts
10638
Joined
7/21/2009
Location
Harrisburg, OR, USA
JW381 1/1/2015 6:47pm
1/1/2015 6:47pm
GeorgiePorgie wrote:
What do you guys run in 144s?
nytsmaC wrote:
I run the above in my 144 and have go between a 195 and 200 main with it, stock was a 190. Give it a try...
I run the above in my 144 and have go between a 195 and 200 main with it, stock was a 190.

Give it a try Justin, what jetting are you using now? You may benefit from going bigger than a 180. I use a 190 in my 250 but stock was a 185.
Well I got it from JD with a 175 in it. 178 is in it now and its good. I'll be interested to see how it handles on top with oxygenated fuel and a fatter main. Thanks for the tips!
kawirider819
Profile picture for user kawirider819
Posts
707
Joined
10/18/2006
Location
st petersburg, FL, USA
kawirider819 1/1/2015 8:03pm
1/1/2015 8:03pm
rcannon wrote:
Running race fuel in a stock yz 250 is a bad aid covering a poorly designed head. You can still run it after having this guy...
Running race fuel in a stock yz 250 is a bad aid covering a poorly designed head. You can still run it after having this guy machine your head, but you dont need to. 100, for sure you should. It works better, and is better fuel, but if your going that far, why not spend an extra 75 bucks and really get some benefit from it?

http://www.rb-designs.com/rb_designs_llc_025.htm

Once you have the head modified, the bike will run better on pump premium, with ethanol, than it will on race gas and the stock head. A number 8 slide is nice, too.

Once the head is correct, the bike is easier to jet, and a lot more responsive. Its not about raising compression, or lowering. Its only about using exact dimensions.
Hmm. Just picked up an 09 yami 250 and was thinking of going this route. Raking up the bills buying race gas.
Aceofspades 1/1/2015 11:29pm
1/1/2015 11:29pm Edited Date/Time 1/1/2015 11:30pm
Rb designs specializes in kdx200 head and carb mods. His ability to turn a kdx200 into a sweet running tractor with a simple modding of the head is legendary. I'd trust him to do ANY head mod for any two stroke. He knows his stuff!
rcannon
Profile picture for user rcannon
Posts
357
Joined
2/11/2007
Location
West Jordan, UT, USA
rcannon 1/2/2015 5:19am
1/2/2015 5:19am Edited Date/Time 1/2/2015 6:38am
rcannon wrote:
Running race fuel in a stock yz 250 is a bad aid covering a poorly designed head. You can still run it after having this guy...
Running race fuel in a stock yz 250 is a bad aid covering a poorly designed head. You can still run it after having this guy machine your head, but you dont need to. 100, for sure you should. It works better, and is better fuel, but if your going that far, why not spend an extra 75 bucks and really get some benefit from it?

http://www.rb-designs.com/rb_designs_llc_025.htm

Once you have the head modified, the bike will run better on pump premium, with ethanol, than it will on race gas and the stock head. A number 8 slide is nice, too.

Once the head is correct, the bike is easier to jet, and a lot more responsive. Its not about raising compression, or lowering. Its only about using exact dimensions.
kawirider819 wrote:
Hmm. Just picked up an 09 yami 250 and was thinking of going this route. Raking up the bills buying race gas.
Once you try it, you realize it was a "must do" sort of thing. I dont know if this is true, but it might not hurt to decide on what specific piston you wan to use, before matching up the head.

The stock squish band, on every yz 250 we checked (@25 bikes) was always off by the same amount. Yamaha must have built them that way. I suspect the extra space might be good if someone had worn crank bearings? Who knows?

Anyway, when he matches the head and piston to the proper spec, I'm nto sure of you could then take you stock piston out and switch to a Wiseco. I had mine set up with the single ring "Wiseco Racers Choice" piston in place.

Back then, Ed hooked me up with a ti-nitrided ring that was developed for Mike Brown. Apparently he reved the bike like it was a 125 and normal rings would not last more than a moto. At my speed, this meant the ring, and piston would last a year or two.

I ended up switching to Eric Gorrs 295 kit, but, at times, I do miss the 250. Especially when the 295 scares me. Both r un excellent on premium, ethanol fuel although Eric did offer a race gas option. At my ability, LOL.






Pit Row

See All »
Shoebomber#1
Profile picture for user Shoebomber#1
Posts
5
Joined
12/30/2016
Location
Holts Summit, MO, USA
Shoebomber#1 4/6/2017 10:40pm
4/6/2017 10:40pm
I own a 2017 KTM 250sx and run 111 octain fuel at 60:1 with klotz oil. It's purple fuel and on its own separate pump so your not getting it mixed with other octain.
The bike runs great no problems yet. 6.16 a gallon but it smells great. Lol
Had a kx250 throw a rod on me and I was running 87 in it, don't know if that caused it but didn't wanna take a chance on the new bike.
CarlinoJoeVideo
Profile picture for user CarlinoJoeVideo
Posts
7517
Joined
11/30/2013
Location
Portland/Los Angeles, CA, USA
CarlinoJoeVideo 4/6/2017 11:21pm
4/6/2017 11:21pm
Langhammx wrote:
C-12 / Pump 50/50 is the proven mixture for me, even in my 4-strokes. Mainly to keep the motor burning clean.
X2. This^
Canadad
Profile picture for user Canadad
Posts
192
Joined
12/5/2012
Location
CA
Canadad 4/7/2017 6:35am
4/7/2017 6:35am
Langhammx wrote:
C-12 / Pump 50/50 is the proven mixture for me, even in my 4-strokes. Mainly to keep the motor burning clean.
CarlinoJoeVideo wrote:
X2. This^
X3
Ozy
Profile picture for user Ozy
Posts
2267
Joined
4/1/2008
Location
USA
Ozy 4/8/2017 1:03am
4/8/2017 1:03am Edited Date/Time 4/8/2017 1:04am
1/2 C-12 and 1/2 91 octane pump gas. should run great and you shouldn't have to mess with the jetting very often after you dial it in
jbonemalone
Profile picture for user jbonemalone
Posts
301
Joined
12/4/2016
Location
Otis, LA, USA
jbonemalone 4/8/2017 5:03am
4/8/2017 5:03am
The best part about Av gas is when you blow your knee up and have six months off the bike it fires right up with the fuel you left in it.
No my bike but my cousin.
He never even washed it after smashing his knee.
An has will remain stable in your tank for a stupid long time.
This was even on a 05 yz 250. Damn thing didn't even detonate after six months of sitting.
Goes to show how proper jetting goes a long way too as well.
Acidreamer
Profile picture for user Acidreamer
Posts
1793
Joined
8/25/2015
Location
Mansfield, OH, USA
Acidreamer 4/8/2017 5:11am
4/8/2017 5:11am
My yz250 requires a minimum of 95 octane according to the service manual. I buy cam2(sunoco 110) at speedway. Runs great. Personally i wouldnt run pump gas at all. That stuff is such low quality fuel. I dont trust it in a motor i spent $1000 on building.
FahQ
Profile picture for user FahQ
Posts
865
Joined
7/5/2015
Location
USA
FahQ 4/8/2017 7:32am
4/8/2017 7:32am
mx965 wrote:
Do not run pump in a two stroke. Ill run 93 out of the pump all day in my 450 but not in the two stroke...
Do not run pump in a two stroke. Ill run 93 out of the pump all day in my 450 but not in the two stroke. Any of you YZ owners pull out your manual it says 95 octane gas or above RIGHT IN THE MANUAL. My cr blew up on pump. I highly advise not to run pump gas in any two stroke.
Although I agree, I would not run pump fuel straight. The 95 Octane that is referenced is RON. Our 93 in the US is R+M/2 which will be higher than 95 RON.
I have tried many race fuels and they all run better than pump, even 100LL
Mx746
Profile picture for user Mx746
Posts
531
Joined
11/30/2010
Location
Marietta, GA, USA
Mx746 4/8/2017 7:52am
4/8/2017 7:52am
VP customer service recommended VP Motosport 98L (MS98L) for use in my stock 14 yz250. It has been very stable and reliable, and I didn't need to rejet.
LungButter
Profile picture for user LungButter
Posts
8684
Joined
1/9/2016
Location
Yellow Pine, ID, USA
LungButter 4/8/2017 7:55am
4/8/2017 7:55am
Skerby wrote:
I wouldn't run pump in any two stroke. I would put the thickest base gasket available in there first, then maybe ok. I know that a...
I wouldn't run pump in any two stroke. I would put the thickest base gasket available in there first, then maybe ok.

I know that a Yz will blow up in short order on pump.
In short order? Really?

I guess the dozen or so I've owned over the years missed that memo.
Jeff_Crutcher 4/8/2017 8:58am
4/8/2017 8:58am
Don't listen to anyone.
Katoomey
Profile picture for user Katoomey
Posts
1714
Joined
1/18/2013
Location
USA
Katoomey 4/8/2017 9:32am
4/8/2017 9:32am
Jeff_Crutcher wrote:
Don't listen to anyone.
before or after I take you're advice?
SoCalMX70
Profile picture for user SoCalMX70
Posts
3565
Joined
4/1/2008
Location
Thousand Oaks, CA, USA
SoCalMX70 4/8/2017 9:45am
4/8/2017 9:45am Edited Date/Time 4/8/2017 9:47am
I wonder how long before the guys claiming the YZ manual says "95 octane" realize that is RON (Research Octane Number)... which is really 90-91 at the pump in the states (or at least here in CA, R+M/2).

Here's some help: https://en.m.wikipedia.org/wiki/Octane_rating

Post a reply to: Best Race Fuel for stock 250 2 stroke