What is the fuel of choice for a Stock Moto CR125?

Derek Lodato

I'm trying to figure out the best fuel to use or my SRS built '99 CR125 Stock Moto engine

Also, What type of fuel container should I store AND transport the fuel: Plastic or Steel container and why?

Thanks

Ryan Leger · Joined: 19 Jul 2012 Posts: 133

Ms98 or c12 if im correct i run c12 and ms98 in mine

Derek Lodato · Posted: Sun Oct 21, 2012 8:28 pm Post subject:

I am in Florida so VP Fuel is not an option .... Any other options?

Ryan Leger · Joined: 19 Jul 2012 Posts: 133

Sory from canada why cant you run vp there possibly sunoco race fuel

Derek Lodato · Posted: Sun Oct 21, 2012 9:19 pm Post subject:

I meant its not readily accessible .....Thanks for your input

al nunley · Joined: 13 Nov 2006 Posts: 3027

Let's go the other way; what are your choices in your area.
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Jim McMahon · Posted: Mon Oct 22, 2012 5:40 am Post subject:

Are you asking about practice or racing? Bottom line is you want something that is 96MON at the minimum if you want to avoid detonation.
Sealed steel container for longer term storage, plastic is OK for a weekend, steel would be preferable.

/Edit.... Did you ask John at SRS? I think he "might" just have a couple of ideas on fuel for you too Wink

.
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marc-andre hubert · Joined: 10 Apr 2012 Posts: 174

im in fort myers and can get VP 3 shops within 5 miles,i run 110 leaded with 7to1 motul runs awesome. you need to come race at racecomplex.com awesome track we need more shifters.

Jason Berry · Advertiser Joined: 29 Dec 2001 Posts: 294

SKUSA requires the VP MS98 fuel for competition. This has been a good fuel choice for the Stock Moto Engine. If you are using other fuel or a replacement, contact each fuel supplier for their specs.

We have 3 options in NorCal for a 98 octane fuel. Of the three, VP MS98 does not cause detonation. The other two require much richer jetting.

Most fuel suppliers offer a 5 gallon steel pail. Only mix enough fuel and oil for the day.
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marc-andre hubert · Joined: 10 Apr 2012 Posts: 174

Florida winter tour is also ms98.. i have only ran the 110 with zero issues do you know if switching to ms98 will affect the jetting alot, i would up the jet size to start but just asking

Spencer Uzri · Joined: 18 Apr 2006 Posts: 798

Jim McMahon · Posted: Mon Oct 22, 2012 1:13 pm Post subject:

The changes in jetting are more to do with the specific gravity of the fuels than its octane rating.
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Cesar Rull · Posted: Mon Oct 22, 2012 8:06 pm Post subject:

Interesting thread. I just contacted my engine builder (also just purchased a Cr125 stock). He mentions 110 octane race gas. Is that the same as what you guys are talking about?

MS98 ?

I am in south florida, what are my fuel choices. Sorry for the stupid question but are these fuels available at any gas station?

Jim McMahon · Posted: Mon Oct 22, 2012 8:22 pm Post subject:

Its not usually available at a gas station. At least not the VP stuff. Some places might have 100leaded on pump. There's a few different methods of calculating Octane. I like to use MON. MS98 is 98octane by the most common method (R+M/2), it's MON is 96. You could try a google maps search for "race gas" in your area and see what crops up.

Long story short, 110 (by any method) will be fine. You will be leaving a little power on the table, but thats not a big issue at his point. One thing that's good about the higher octane leaded fuels is that the extra lead is very kind to bearings and so forth, so from that perspective they are perfect when you are looking to get seat time and have maximum reliability. That might be the basis of the recommendation.
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Cesar Rull · Posted: Tue Oct 23, 2012 1:42 am Post subject:

so do I just go to any gas station that sell race gas 110 octane and buy some? Then mix it with castor oil and I am good to go?