100ll av gas yz250

Sipes #412
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Tacoma, WA US
3/9/2017 8:24am
I just bought a 2007 yz250 stock no head mods and the guy highly recommended me to run 50/50 race/pump gas but I've done little research on 100ll as a cheaper option because I don't want to spend 50 dollars on 5 gallons of race gas. First question is would I be fine running 92 octane? I have in the past on my yz's and haven't noticed issues. He told me they come from the factory to run race gas well pretty close. I wouldn't mind spending 5 bucks a gallon on 100ll. is it better to run higher octane on 2 strokes or will I be fine on 92 octane?
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Jmicmoto13
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Troutman, NC US
3/9/2017 8:26am
I run 100LL in my bikes with no issues. I mainly love it because A. It has no shelf life so it doesn't degrade it my carb or gas can when it sits and B. It offers a little crisper throttle response. I have been getting 10 gallons at my local airport for $36.
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Braaaphole
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Spring, TX US
3/9/2017 8:03pm
I'm running 100LL as well in my 03 CR250. In all fairness, you shouldn't need higher octane with your bike being stock. 92 should run fine. I switched because my bike was detonating and going to higher octane fixed that for me. Plus the added benefit of it being leaded and the no shelf life. All the pump gas around here is E85 and that stuff is straight garbage in bikes.
1
captmoto
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Rancho Cucamonga, CA US
3/9/2017 11:26pm
Between ethanol and clean air additives, most pump gas is shit. You can look up RB designs in Oregon and they will cut your head to work with pump gas.
I run avgas in my YZ465 and in the 05 CR250 that I had. No issues and the bikes ran great. Go for it you will not be sorry.
1
Rockinar
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3/10/2017 1:26am Edited Date/Time 3/10/2017 1:28am
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane will do nothing in a stock bike but smell nice and empty your wallet.

On page 1-20 of your owners manual it say the bike is designed for 91 or higher octane pump gas, or 95+ RON (Research Octane Number).


As a private pilot, I would advise not to go putting 100LL in a bike. Theres a ton of reasons why. Main one is its just not designed for automotive and none of the additives are either. I bet pump 93 octane gas would run better.



Run pump gas, if it knocks, throw a splash of C12 in it. Stay away from 100LL. Its for planes and design for engines running at high altitudes. I would scratch it off my list.
2

The Shop

mattyhamz2
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3/10/2017 9:14am
Rockinar wrote:
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane...
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane will do nothing in a stock bike but smell nice and empty your wallet.

On page 1-20 of your owners manual it say the bike is designed for 91 or higher octane pump gas, or 95+ RON (Research Octane Number).


As a private pilot, I would advise not to go putting 100LL in a bike. Theres a ton of reasons why. Main one is its just not designed for automotive and none of the additives are either. I bet pump 93 octane gas would run better.



Run pump gas, if it knocks, throw a splash of C12 in it. Stay away from 100LL. Its for planes and design for engines running at high altitudes. I would scratch it off my list.
+1 on this. I would never run av gas in any of my bikes, mainly because it is designed for high altitudes and im sure as hell not riding at anything over 4000ft above sea level.

I do have a stock 05 KX250 that runs like crap on pump gas so we just run c12 or VP110 and it runs awesome!
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Matt Fisher
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3/10/2017 9:32am
Rockinar wrote:
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane...
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane will do nothing in a stock bike but smell nice and empty your wallet.

On page 1-20 of your owners manual it say the bike is designed for 91 or higher octane pump gas, or 95+ RON (Research Octane Number).


As a private pilot, I would advise not to go putting 100LL in a bike. Theres a ton of reasons why. Main one is its just not designed for automotive and none of the additives are either. I bet pump 93 octane gas would run better.



Run pump gas, if it knocks, throw a splash of C12 in it. Stay away from 100LL. Its for planes and design for engines running at high altitudes. I would scratch it off my list.
mattyhamz2 wrote:
+1 on this. I would never run av gas in any of my bikes, mainly because it is designed for high altitudes and im sure as...
+1 on this. I would never run av gas in any of my bikes, mainly because it is designed for high altitudes and im sure as hell not riding at anything over 4000ft above sea level.

I do have a stock 05 KX250 that runs like crap on pump gas so we just run c12 or VP110 and it runs awesome!
AvGas works fine at low altitudes. Every pilot I've known says the most important time for the engine to be 100% is at takeoff, and that's certainly not at 10,000 feet.

While many stock bikes do not need the additional octane, the consistency and lack of crappy additives make 100LL so much better than pump swill for anything performance oriented.
3
Braaaphole
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3/10/2017 3:06pm
Rockinar wrote:
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane...
Stock bike does not need race gas. Race gas is for high compression engines to avoid detonation. Stock bike is not high compression and high octane will do nothing in a stock bike but smell nice and empty your wallet.

On page 1-20 of your owners manual it say the bike is designed for 91 or higher octane pump gas, or 95+ RON (Research Octane Number).


As a private pilot, I would advise not to go putting 100LL in a bike. Theres a ton of reasons why. Main one is its just not designed for automotive and none of the additives are either. I bet pump 93 octane gas would run better.



Run pump gas, if it knocks, throw a splash of C12 in it. Stay away from 100LL. Its for planes and design for engines running at high altitudes. I would scratch it off my list.
I've seen this before and it's absolutely not true. AV gas has to run at a wide range of altitudes. The most important time for it is during take off when the engine is under the hardest load.

I wouldn't run AV gas in a 4 stroke, but in our old 2 strokes it works perfectly fine. Look around, there's numerous cases of people running it for years with no issues. I've yet to find a single case of someone having an issue because of running it in a 2 stroke.
3
BobPA
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3/10/2017 7:36pm
mattyhamz2 wrote:
+1 on this. I would never run av gas in any of my bikes, mainly because it is designed for high altitudes and im sure as...
+1 on this. I would never run av gas in any of my bikes, mainly because it is designed for high altitudes and im sure as hell not riding at anything over 4000ft above sea level.

I do have a stock 05 KX250 that runs like crap on pump gas so we just run c12 or VP110 and it runs awesome!
Runs awesome while making less power....
BobPA
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3/10/2017 7:37pm
AvGas works fine at low altitudes. Every pilot I've known says the most important time for the engine to be 100% is at takeoff, and that's...
AvGas works fine at low altitudes. Every pilot I've known says the most important time for the engine to be 100% is at takeoff, and that's certainly not at 10,000 feet.

While many stock bikes do not need the additional octane, the consistency and lack of crappy additives make 100LL so much better than pump swill for anything performance oriented.
This
avmechanic
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Langley BC CA
3/10/2017 9:19pm
I am an aircraft mechanic and have used Avgas in my bikes and hot rods for years. Often I mix it with as little as 50% along with regular gas. It works great in my 4 stroke and 2 strokes. It has a shelf life of years so I don't have issues when my car or bike stays parked over the winter. I actually like to put it in the snow blower and lawn mower for when they sit in their respective off season. Drawbacks are really none. It works great for consistent performance and kills detonation in high compression engines. I have heard all kinds of stories on why not to use it and they are all horse shit as far as I am concerned. I have even known a sportsman drag racer who had his own race gas recipe that used avgas. I would say buy some and mix it 50 50 avgas and regular then mix with your favourite oil. I highly doubt you will be disappointed with the clean crisp performance.
Greg
2
JM485
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Davis, CA US
3/10/2017 9:40pm
My 15 yz250 has seen nothing but a 50/50 mix of pump and avgas since new, and I'm at over 110 hours with 0 issues. It's essentially just very high quality fuel with a very small amount of lead added, nothing that is going to give you more power. Talking to older guys at the airport, they all have some story about how they used to run it in their bike, or lawn mower, or whatever, it's just good stuff.

As for the altitude argument, consider this. On commercial airliners (I know they don't run on avgas but the explanation still holds), engines that do short runs, say from San Francisco to LA, have a much shorter service life than engines that do longer runs, say San Fran to Australia. The reason being is that the engines are taxed the most during takeoff, where the air is most dense and power is at an absolute maximum. This tells me that for any airplane, power at takeoff is incredibly crucial, and the fuel must work well sea level to provide that needed power. Sure, there may be better fuel options out there, but for just quelling detonation and raising octane there is no reason to waste money on race gas, you're just pissing it away for no benefit.
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3/11/2017 1:23am
Avgas works great... the storys about this reason or that not to use it are usally told by someone who dosnt know or was told a load horseshit by a guy who sells race gas. We used it in Australia in all.the factory yamaha race teams i ranin the 80s 90s and we would still be using it here except they band leaded fuel of any kind ( the fine here for running av gas from our EPA is astronomical ).
3
hellion
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Westfield, MA US
3/11/2017 5:50am
15' YZ250, almost always run avgas as it's relatively cheap, high quality fuel and it's available close by. Most who tell you not to run it, have no experience with it. I've run it for twenty years in extreme conditions often, and it's always worked well. If you can afford, or have access to real race fuel, it's probably the best. But avgas is far better than the pump fuel that contains alcohol which attracts water, and is often dirty to begin with. Use it in my lawn equipment too, and it doesn't gum up the carb like pump fuel will when sitting for extended periods.

Someone above said you don't need the octane for stock engines. Well, the YZ is very on edge stock, and will detonate in extreme conditions. The 100LL is just the right fuel to ensure that doesn't happen.
2
JB426
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NM US
3/13/2017 10:38am
I agree with most of these guys here, I've researched it quite a bit and many people with considerable more knowledge than me have said it's great option. In my experience it has worked great as well. If you have access to it and you don't want to run the inconsistent ethanol enriched pump gas then give it a try. Most do not need or want to spend the money on race fuel so 100LL fills the need for a high quality fuel nicely.

Race fuel > 100LL > Ethanol pump fuel.
2
3/14/2017 12:02pm
I say run it. Many people say you shouldn't or its bad for an engine but have you ever seen a post by someone saying they used it and it ruined their engine?? I havn't. Everyone that has tried it has nothing but good things to say and those that say don't use it are people that havnt tried it.
1
FahQ
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NJ US
3/14/2017 1:56pm
I have used it for years. It will not ruin your engine, It will protect your engine!
It may not perform as well as pump or race fuel, unless modified to do so.
Having said that, to the OP if previous owner said it needs 50/50 he might have experienced some pinging at one time.
YZ's are known to have static timing variances enough to cause pinging,
especially after rebuilding with a Wiseco crank.
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Jterry
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Cottondale, AL US
3/14/2017 7:52pm
Ive used it for years in my YZ250's works fine and its way better than junk pump gas.
1
BobPA
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PA US
3/14/2017 9:27pm
FahQ wrote:
I have used it for years. It will not ruin your engine, It will protect your engine! It may not perform as well as pump or...
I have used it for years. It will not ruin your engine, It will protect your engine!
It may not perform as well as pump or race fuel, unless modified to do so.
Having said that, to the OP if previous owner said it needs 50/50 he might have experienced some pinging at one time.
YZ's are known to have static timing variances enough to cause pinging,
especially after rebuilding with a Wiseco crank.
I heard Wiseco cranks also cause rebuilds....
3
adam8781
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CA
3/14/2017 10:30pm
the stock head design is terrible, dont run 100ll, the stock head with squish corrected and machined to stock ccs will run better on pump fuel than the stock head on 100ll
Jmicmoto13
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3/15/2017 12:32pm
Lol so many conflicting opinions.
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Sipes #412
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Tacoma, WA US
3/24/2017 8:54pm
avmechanic wrote:
I am an aircraft mechanic and have used Avgas in my bikes and hot rods for years. Often I mix it with as little as 50%...
I am an aircraft mechanic and have used Avgas in my bikes and hot rods for years. Often I mix it with as little as 50% along with regular gas. It works great in my 4 stroke and 2 strokes. It has a shelf life of years so I don't have issues when my car or bike stays parked over the winter. I actually like to put it in the snow blower and lawn mower for when they sit in their respective off season. Drawbacks are really none. It works great for consistent performance and kills detonation in high compression engines. I have heard all kinds of stories on why not to use it and they are all horse shit as far as I am concerned. I have even known a sportsman drag racer who had his own race gas recipe that used avgas. I would say buy some and mix it 50 50 avgas and regular then mix with your favourite oil. I highly doubt you will be disappointed with the clean crisp performance.
Greg
I will take your advice and run 50/50. Sounds a lot better than spending $90 for 5 gallons of race gas.
1
SlS257
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West Palm Beach, FL US
3/25/2017 5:13pm
Stock 07 will ping on pump gas. Mix it 50/50.
1
3/26/2017 4:37pm
SlS257 wrote:
Stock 07 will ping on pump gas. Mix it 50/50.
Stock YZ250's in general will ping on pump gas. Always run at least 50/50 with them.
1
354racing
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Kingston, GA US
3/30/2017 4:32am
I use 100LL 50/50 with no ethanol pump gas. 87 octane mixed with 100LL will be 93 octane and 90 octane will be 95 octane.I run it in my 4 strokes and my smokers.Runs fine and no junk ethanol in it.
1
slothy
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Saint Clair Shores, MI US
3/30/2017 8:12am
whats the going price for av gas?
captmoto
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3/30/2017 11:19am Edited Date/Time 3/30/2017 11:20am
Jmicmoto13 wrote:
Lol so many conflicting opinions.
I wasn't giving an opinion. Opinions are usually different than experience. I gave my and only my experience. Avgas brought my YZ465 to life. After adding only avgas it became a way easier starter. Runs cleaner through the RPM range. You can leave Avgas in the bike for more than 2 weeks. It stores forever and mixes easily. If Avgas was going to hurt a motor it would hurt this rattling, air cooled, jack hammer, high compression motor don't you think? This bike has been a winner at Day in the Dirt with a 20 year old WORCS intermediate riding it and he never hurt the motor.

My 05 CR250 was a rattle trap on pump. I ran a 50/50 mix of C12 and pump 91 and the pinging went away but I was still paying + $7 a gallon for the mix. Avgas is around $4 a gallon. I could have cut the head on the CR to run on pump but I would still be dealing with poor gas quality, short shelf life and possible oil and gas separation. Also ethanols attraction for water.
I also ran the mix in the 465. My seat of the pants dyno said no performance distance. I don't know if Avgas is a HP boost but it felt like it because both bikes ran crisper and were more responsive at the throttle.

And finally, I bought a $59 string trimmer at Home Depot for a clean up project. I thought for $59 I could throw it away when I was done with it. That thing has only run Avgas and Maxima SuperM and is running perfectly after 7 years.
Now, it is reported by MXA that the YZs will rattle and eventually break on pump gas. OP can have the head milled by RB Designs to run pump but will still have to deal with shitty gas quality unless he can find ethanol free gas. It won't hurt to try 1 gallon of Avgas.
1
Jmicmoto13
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3/30/2017 11:38am
captmoto wrote:
I wasn't giving an opinion. Opinions are usually different than experience. I gave my and only my experience. Avgas brought my YZ465 to life. After adding...
I wasn't giving an opinion. Opinions are usually different than experience. I gave my and only my experience. Avgas brought my YZ465 to life. After adding only avgas it became a way easier starter. Runs cleaner through the RPM range. You can leave Avgas in the bike for more than 2 weeks. It stores forever and mixes easily. If Avgas was going to hurt a motor it would hurt this rattling, air cooled, jack hammer, high compression motor don't you think? This bike has been a winner at Day in the Dirt with a 20 year old WORCS intermediate riding it and he never hurt the motor.

My 05 CR250 was a rattle trap on pump. I ran a 50/50 mix of C12 and pump 91 and the pinging went away but I was still paying + $7 a gallon for the mix. Avgas is around $4 a gallon. I could have cut the head on the CR to run on pump but I would still be dealing with poor gas quality, short shelf life and possible oil and gas separation. Also ethanols attraction for water.
I also ran the mix in the 465. My seat of the pants dyno said no performance distance. I don't know if Avgas is a HP boost but it felt like it because both bikes ran crisper and were more responsive at the throttle.

And finally, I bought a $59 string trimmer at Home Depot for a clean up project. I thought for $59 I could throw it away when I was done with it. That thing has only run Avgas and Maxima SuperM and is running perfectly after 7 years.
Now, it is reported by MXA that the YZs will rattle and eventually break on pump gas. OP can have the head milled by RB Designs to run pump but will still have to deal with shitty gas quality unless he can find ethanol free gas. It won't hurt to try 1 gallon of Avgas.
And I wasn't specifically quoting or calling your statement an opinion. If you look at the top I already stated something similar to your experience. I'm a fan of Av gas and at $18.90 for 5 gallons, it works for me.
1
captmoto
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3/30/2017 4:59pm Edited Date/Time 3/30/2017 5:01pm
Jmicmoto13 wrote:
And I wasn't specifically quoting or calling your statement an opinion. If you look at the top I already stated something similar to your experience. I'm...
And I wasn't specifically quoting or calling your statement an opinion. If you look at the top I already stated something similar to your experience. I'm a fan of Av gas and at $18.90 for 5 gallons, it works for me.
I got it, I just wanted to put it out there for people thinking opinion was the same as experience. That's exactly what I got Avgas for last time too. When I bought some C12 for $72 my palms were sweating hoping I would be putting some magic elixer in my bikes.
I think VP sells 2 stroke gas that is 100 octane for stock motors so Avgas is well withing stock jetting and compression.
1
Squirtlege
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Neptune Beach, FL US
3/31/2017 1:28pm
+1 for AV gazzzzz... I run 50/50 mix AV 100ll and 89 ethanol free from a quality supplier in town. Granted I'm on 4 strokes, but here in Florida the gas is so bad at the pump due to our humidity, that it's just easier for me from a shelf life and quality point of view...and under $4 gallon. Run it in all my lawn equipment, my neighbor builds hot rods and always says my John Deere mower must be a 1000 HP when he smells it go by.
1

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