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290
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7/15/2009
Location
Auburn, ME
US
Edited Date/Time
11/13/2017 3:24pm
I sponsor a rider who is currently racing a YZ125 and YZ250. I'm looking for opinions, suggestions, and experience with these two fuels from VP. We run Amsoil dominator premix and am looking to run one of these fuels 50/50 with 93 pump gas.
Thanks in advance!
Thanks in advance!
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will work fine cut 50/50 with premium pump gas yielding an octane rating over 100. As I'm sure you already
know, It's a good idea to secure a source of ethanol free pump gas for the mix.
The MRX02 and SX2 are both oxygenated and expensive. VP claims the MRX02 is legal for AMA Pro/Am,
but I'm pretty sure oxygenated fuel is not legal for AMA pro racing. The Renegade 110+ is also leaded and
another good choice.
I have used all of the above fuels straight and cut and it's all good quality.
Other things to keep in mind: What access to the fuel do you have, shipping cost (if needed), drum size, shelf
life, etc. As the one paying the bills, these underlying cost and considerations should also figure into your
decision on brand and type.
dogger
MRX02 is leaded which is not allowed in AMA Pro racing and contains more oxygen than allowed in AMA Pro racing but it is legal in Amateur racing and Pro/Am events.
If the op is looking for performance he should get the oxygenated fuel for 2 strokes and if he just wants fuel safe for a 2 stroke and cheap then the C12 or 110. In my experience, straight C12 or 110 make less power on the dyno than 93 pump and 50/50 mix with pump. We use C12 or 110 to put in bikes after we drain the oxygenated fuel and then run them a few minutes for storing until the next ride.
Lady looked at me so weird when I bought a half gallon the other day haha it was all the premix I had left in a little bottle and I just wanted to put it to use!
http://motocrossactionmag.com/Main/News/RACERS-GUIDE-TO-THE-HIERARCHY-O…
As for C12 in a 2 stroke it works quite well but a few things here to note.
In a stock or slightly modified 2 stroke you are wasting your money. The engine needs to be modified to the hilt to get all that you can out of it I.E. Porting, Pipe, Carb, Ignition and compression. To get the best results you will need to fine tune the engine on a dyno to get the jetting and timing fine tuned to get the best results.
One other thing to remember with a 2 stroke is the oil and how much you use in your premix. Most riders like to use less oil thinking that they are making more power with it, The fact is more oil equals more HP as it improves the ring seal and allows the engine to run cooler.
One other person noted that 2 strokes need leaded fuel. Not true. The lead is a cushioning agent for valves that do not have hardened seats. As a smoker does not have valves that open and close to let air in and exhaust out it is not needed. The one thing lead does is it also increases octane levels in a fuel. When working with a leaded race fuel always make sure to wear protective gloves and safety glasses as the lead can be absorbed thru the skin.
Tried the U4.4 and Jake said he really couldn't tell a difference, pulled through the corner the same and shift points stayed the same. Testing on the same track using different fuels, did have to go 1 richer on the oxy fuel.
This post is a couple years old so I'm curious whether I should stick with VP110 or whether one of the newer blends would be better. I'm less concerned with power as I am with having a longer lasting race fuel (compared to other race fuels).
So, 2015 - still run VP110 or C12, or something else?
Pit Row
i run it straight, and since its almost HALF the cost of C12 its a no brainer.
no reason to run mrx02, c12, c16, ect unless you have an engine built and need it. 15-25$ a gal gas adds up, quick.
trying VP T2. It's leaded, oxygenated and has a MON of 101 which should be more than enough for your application. I
don't know what it cost, but might be worth a try. I would give VP a call and tell them what you have and see what they
recommend. Their tech people are real helpful.
dogger
https://www.airnav.com/fuel/local.html
Quick question.. I'm installing a RAD valve in an essentially brand new 89 KX125 motor (literally new everything except for the replated cylinder and cases). OEM expansion chamber & freshly packed silencer.
Boyesen recommends stepping down between 1 and 3 on the main and putting the needle at the middle position for starters. I moved down from a 155 main to a 150.
Will I need to readjust on account of the VP110? Plan to run Klotz R-50 at either 32:1 or 40:1.
Also:
AvGas is blended for large-bore, long-stroke, low RPM engines which run at high altitude. While AvGas' higher octane is useful, smaller-bore, shorter-stroke, high RPM engines will perform better on racing fuel or high quality octane boosters. AvGas has lower volatility so when used in proportions higher than about 40%, part-throttle drivability and cold starts may be compromised. AvGas has a lower specific gravity so it will require a change in air-fuel ratio calibration for the engine to perform at its best.
Also, and this is going to sound weird, Avgas is very "dry" feeling and have noticed that if you run it then you need to run a lot more pre-mix than a normal race fuel. I would never run anything lower than 32:1 using Avgas.
You can get Renegade 110 for about $7 a gallon at the pump in the Midwest. It would be safer than Avgas
However, if you have not had any engine work, higher compression to be exact, race fuel will basically do nothing for you besides just being consistent and no alcohol mixed in like at the pump.
We have to run straight C12 in our 125 because it is a built motor but in my 250 I just add 1 gallon of Renegade to 4 gallons of 93 octane strictly for detonation purposes only. In the stock 250 motor I have thrown the C12 in there just because it was the only thing we had at the time and could not tell any difference in performance from the 93 octane pump gas
All the criticism of avgas is totally unfounded and perpetuated by people that have never used it.
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