Not that many things on here regarding fuel and the Yz125 specifically. Locally, I can only get 91 octane ethanol gas, which is not what the manual calls for. It calls for 93 or higher......I have two other options each about 20 miles away....one is 93 octane ethanol gas from the pump, or go to sunoco and get 110 octane ethanol free......Any thoughts? Keep in mind, my engine is stock, and I don't plan to mod it out a whole lot in the near future. Any harm to running the 110 gas? 

I don't think you'd have any issues running 91 in it.

I use Sunoco in my yz125. I use 3 parts 91 to one part Sunoco 110. I only use it on moto tracks when I will be running hard on full throttle. I don't use while trail riding.
There are different rating for fuel. 91 octane in the US is okay in a yz125, but it's borderline.

I used Sunoco110 mixed with Shell V Power non ethanol in a 50/50 mix. In my 2003 YZ125, I started with it in a standard engine and it performed much better for me, much cleaner throttle easier to jet and plug colour read. Mixes well with Motul oil. 110 is a good fuel and you can run it as is,  just the cost and you wont get the full benefit with a standard motor ,  but I would easily prefer it to an ethanol pump fuel.

Edited by TommyCrown

Handy race fuel blending calculator: http://www.motorsportsracingfuels.com/OctaneCalculator.html

 

My 2010 YZ125 is all stock except for Boyesen reeds and a reduced squish band height, from the stock 1.37mm down to 1.05mm or so.

As the dome volume cc's were not corrected it gained a modest 5psi of compression and averages about 185psi on a fresh top end.

 

Even before this I had always ran about 15% race fuel to 91 pump premium for an average of about 94.5 octane (R+M/2 Canada/USA rating method)

Initially some VP C12, then VP 110 and now Sunoco Standard 110.

Maybe not for trail riding but for motocross (even moderate paced recreational speeds) a YZ125 in stock form is borderline okay on 91 pump fuel

but with always questionable quality (ethanol, tank mix-ups etc.),

call it preventative insurance  in case you ever get a bad batch at the pump.

 

 

Edited by mlatour

I use the 112 mixed with super pump, sea foam, and its at 1 to 4. 

I use Sunoco 110 pump gas in YZ250. Runs great, stores longer and no ethanol. 

I use Sunoco 110 pump gas in YZ250. Runs great, stores longer and no ethanol. 

If I remember correctly, its 5 years in a sealed container.

Maybe overly optimistic but the Sunoco fuel dealer where I purchase mine mentions

up to 2 years useful life after the container has been opened, as long as it's properly stored.

Even said adding Sta-Bil (which I do) is un-necessary.

 

I've gone 6+ months from an open 5 gallon pail without any noticeable loss in performance.

 

 

Edited by mlatour

2 year sealed. Six months opened is safe. I run Sunoco 260 GTX. It’s 98 octane unleaded, ethanol free, smells wonderful as well.

I run AVGas 100 octane in my Yz250, performs just as well as VP C12 at 5.50 a gallon.. ethanol is an inconsistent dogshit of a fuel for 2t’s.. I find it makes getting jetting spot on difficult as well, there’s not much consistency in pump gas imo

23 hours ago, delleetodd said:

I use Sunoco 110 pump gas in YZ250. Runs great, stores longer and no ethanol. 

Do you have a stock engine? I am think about draining the tank and running 110 this weekend at the track to just see what happens. Also, I want my engine to last as long as possible, but may end up doing some mixing as well. Guess I will just play around with it and see what I like best. 

That storage time is awesome though...didn't know about that. 

VP110 and 91 pump 50/50 is what I run. Bikes runs fantastic (and smells good haha)

6 hours ago, Taylor Robinson said:

Do you have a stock engine? I am think about draining the tank and running 110 this weekend at the track to just see what happens. Also, I want my engine to last as long as possible, but may end up doing some mixing as well. Guess I will just play around with it and see what I like best. 

That storage time is awesome though...didn't know about that. 

Yes stock engine and I get Sunoco 110 right from a pump locally. Runs greAt. 

Bought some Sunoco today, gonna go 50/50 with some 89 non ethanol at the local stations. Should give me about 99ish octane. Ill keep y'all posted and let you know how it goes this Saturday. 

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