Race gas for RM250

[Chili]

So since my bike is 100% stock, I shouldnt use it. I should only use it if I start modifying the bike.

Not necessarily. We just rebuilt my son's 03 RM125 with a bone stock engine (aftermarket pipe and silencer) and jetting where we thought it was pretty good but still a tad on the safe side of rich (the jetting not Rohrich :laugh: ) The piston showed mild signs of detonation, it had been run since new on Premium pump and Yamalube2R at 32-1. The mechanic who helps out our race team suggested after looking at the piston we either go to mix of race/pump fuel or start using some of the unleaded version of THIS PRODUCT. Due to cost factors we are trying a trial batch of the Torco accelerator instead of the blend of pump/race fuel. Unfortunately I haven't been able to find any technical info on the Torco product or get any feedback other than from a couple of local wrenches who use the product. We ran it last weekend and didn't notice any difference in performance. I guess the real answer will come at the next re-ring when we can see if we are still getting mild detonation.

 

[nephron]

MXSparx--I can't add anything to what Rich said, except that from what I've read (of what he's written ;) ), mixing race and pump can yield unpredictable results at best. Provided the pump fuel components don't change seasonally, and provided you've got it jetted spot on for that mix, it's working for you. So keep it. Despite that, the mix may introduce a fluctuation in the distillation curve, anywhere along its point, leading to possible air:fuel issues at particular rpms. It seems to be easier to jet on spec fuel, and more consistent.

I think if you've got money to spend on it, and/or you really care for that last percentage of hp improvement (more importantly, throttle response off the bottom on the low 10% point fuels), then you should do it.

Obviously, if money's an issue, or you'd just prefer not to 'waste' the money....personally, I would stick with pump provided the motor in question will tolerate it well.

If anyone's ever seen a distillation curve on pump fuel, you'll know what this is about. If you haven't, as I recall, I found some good info on Chevron's site, but haven't looked in months.

 

[Glitch]

Rich or some other fuel guru,
I just got bought an 02 yz125 with Stage 3, FMF sst pipe and shorty, and rad valve. The guy I bought it from said he runs klotz 110 with klotz r-50 at 32:1, so thats what I'm running right now. But I haven't heard too much about klotz, just mainly vp. Since I'm buying race gas, I wanna run the most correct fuel for my bike setup. Are there a couple fuels that you think should be at the top of my list. I looked at the vp site but theres a ton of fuels for motocross. Also, the stock jetting is in the bike, and it aint working too well, so does anyone have some suggestions as to which direction(lean/rich) I should jet each circuit with all the mods and race fuel. Gonna pick up some jets on monday, and maybe some different type of fuel.
Thanks alot :worship:
Jim

 

[bedell99]

The fuels I listed are good motocross fuels. (VP C-12, MR2, /Phillips B32(TT111),33(TT114),35(TT101), /Sunoco Sumpreme Unleaded 112, MX 114, M02X)

If you have access VP, the cheapest is C-12 and is a good baseline to start with. It is non-oxygenated-leaded and has a nice distillation curve.

Erik

 

[steve125]

The fuels I listed are good motocross fuels. (VP C-12, MR2, /Phillips B32(TT111),33(TT114),35(TT101), /Sunoco Sumpreme Unleaded 112, MX 114, M02X)

Eric you missed one! The best 2 stroke fuels VP sells IMO is, the Ultimate-2 and Ultimate-4. It jets easy, good detonation protection, super throttle response, and most importantly, it makes POWER! :worship:

It's Ok to use the VP U-4 in stock 2 stroke engines and the U-2 in the modified ones. Or even blend the 2 fuels, to tune for your octane requirements.

The guy who said don't use race fuel in stock race motors, well he just hasn't done his homework.

 

[Rich Rohrich]

The guy who said don't use race fuel in stock race motors, well he just hasn't done his homework.

LOL , I wish I had said that. :worship:

 

[bedell99]

Eric you missed one! The best 2 stroke fuels VP sells IMO is, the Ultimate-2 and Ultimate-4. It jets easy, good detonation protection, super throttle response, and most importantly, it makes POWER! :worship:

It's Ok to use the VP U-4 in stock 2 stroke engines and the U-2 in the modified ones. Or even blend the 2 fuels, to tune for your octane requirements.

The guy who said don't use race fuel in stock race motors, well he just hasn't done his homework.

Steve,

That stuff seems almost too good to be true, but from what i hear is it works. The only problem its going for $11.00 a gallon here. To me that is insane. I really want to try it though one day. It's just so hard for me to shell out $44.00 to go riding for a day plus expenses. There is a gas that Sunoco is selling that"almost" comparable. It is called MO2X. It an oxygenated leaded race fuel made especially for motocross applications. The only thing I see different is the percentage of oxygen, but the curves look mighty close. That goes for $8.50 a gallon, but there is a loop hole. You have to buy it in 55 gallon drums from the distributor here. VP fuels are very expensive here for some reason, while Sunoco and Phillips/Track Tek are more reasonably priced. I have been using a fuel called TT114, which I find to be good and priced very well at $4.80. It is very similar to C-12. Here are some good websites for you guys to look at and explore. When looking at a gas look at its MSDS table. There is a wealth of info on them and also here on dirtrider.

Sunoco: http://www.racegas.com

Phillips/Track Tek: http://www.cpchem.com/fuels/products/racingfuels.asp

VP race fuels: http://www.vpracingfuels.com/index2.html?mgiToken=0C15B7C87B135CCC80


Erik

 

[Glitch]

Steve125,
I saw you said mix to your bikes octane requirements. I'm using klotz 113 octane, but would the klotz 104 octane be more logical for my application. I thought I remember reading someone saying that running too high of an octane actually slightly lessens the performance compared to running the octane just required. I dunno about this though, only thing I can think of is why waste the extra dough for the higher octane. I can get both of these octanes for about 6 bucks, should I keep running the 113 or switch to the 104, all while looking for a local vp distributer.
Thanks
Jim

 

[steve125]

Jim, first off what bike are we talking about? The YZ 125? Is it stock or has it had motor work done?

Yes I believe too much octane is a waste, but its better to have too much if your not sure. Thats the real trick here, to only have as much as you need. It's all part of tuning on the edge. I listen for pinging, read the plug for jetting and timing, look at the piston and head for erosion. Also take the track conditions in to consideration and how that loads the engine. The rest is all feel and experience.

I always use the MON rating for octane and my motors seem to run best from 95-98 MON. These motors are set up for race fuel and have cranking compressions around 200 psi.

So if your YZ is stock run the U-4, if its modified go with the U-2. lately ive been running 75% U-2 with 25% U-4 with good results. Seems a bit crisper with this mix than U-2 straight, and 25% U-4 is as far as I want to back the U-2 down.