Race Fuel and Pump Gas

[motobarr]

I have a brand new stock 05'Yamaha YZ250. Not knowing much about race fuel-how many different brands of race fuel are there? How much in general is the best and cost per gallon? Also which brand of pump gas( as an alternative to race fuel) has the highest octane? Is there a premix that works best with one or the other? or it doesn't matter? I apperciate everyones advice and knowledge. Thanks

 

[bobby bo]

i might be wrong but having a stock yz250 running race you will see no improvement, you'll be waisting money. you need race gas when you take your compression up. just use 93 pump gas with a good premix and you'll be fine..

 

[robwbright]

The race fuel is far more predictable for jetting purposes.

Run a search for "race fuel", "pump fuel", "race gas", etc. . .

There's a whole lot more to consider about it than just octane and compression. Evaporation points, etc. . .

http://www.eric-gorr.com/techarticles/fuel_terminology.htm

http://www.eric-gorr.com/techarticles/Fuel_Basics.htm

 

[+30]

Im not a fuel expert but as i understand it, the non-oxygenated race fuels like c12 will have little effect on horsepower but are a good quality fuel and you know what your getting vs the pump.You can burn through some big money trying fuels and trying to jet for different types. The oxygenated fuels are reported to increase hp and most riders report increase in throttle response. I have been using mr2 and u2 in my stock motors. It may be just me but the mr2 seemed to be a little more effort to jet for than the u-2. I have been able to use pump fuel for practice and u2 for racing without any significant jetting issues. the stuffs not cheap but then neither is pump gas...and then theres the smell...youll either love it or hate it.

 

[WhiskythrottleKeit]

The newer YZ250 do tend to knock on pump fuel. Me and my brother run 40/60 race pump mixture in our YZ250 this is all it takes to stop the pinging and you will gain power due to the none audible pinging being gone.

 

[rbn14]

My YZ was knocking a bit also, I run 50/50 with pump gas and SUNOCO 110. I think any brand race fuel will be fine, just use what you can get a good price on.

 

[psalm3124]

Whiskey & Rbn,

I've got an 06 YZ250 and I'm thinking of mixing pump with sunoco 110, did you have to rejet your bikes?

 

[WhiskythrottleKeit]

youll be fine thats what we run. Just adjust your air screw and ride :ride:

 

[psalm3124]

This might sound like a dumb question, but I'm trying to get a handle on the race gas thing. So when I run 50/50, will I need to adjust the air screw so the fuel is richer or leaner? Approx how much of a turn(s)?

 

[rbn14]

Turning the air screw in will cut back air (richen) and turing out will add air (lean). Check out the jetting sticky, one of the links talks about seting up the pilot circuit, that should get you dialed in. Plus, its not going to affect the jetting much if at all, by mixing sunoco 110 with pump gas you are basically just bumping up the octane a couple of points, if you were going to use a heavily oxiginated fuel it would be another story.

 

[psalm3124]

Rbn,

I understand jetting. :cool: What I don't understand is how 50/50 will affect jetting. :bang:

Since we have the same motor which way did you turn your air screw? In to richen or out to lean?

Thanks.

 

[Rich Rohrich]

Rbn,

I understand jetting. :cool: What I don't understand is how 50/50 will affect jetting. :bang:

In the SPECIFIC case of normal US pump premium mixed with Sunoco 110, more fuel will vaporize under most conditions except very light load partial throttle positions. As a result the engine will tend run rich compared to 100% pump fuel and most people will have to lean the needle and main jet and possibly the air screw or pilot jet.

How much YOU have to change the jetting to account for the fuel difference will depend on your riding style, the load you subject the engine too, and how close your jetting is to correct now.

No one can give you an exact answer to that question, but I realize that won't stop any number of people from doing it anyway. :whoa:

I hope this helps. ;)

 

[psalm3124]

Rich, your first paragraph answered my question perfectly. Thanks.

 

[Rich Rohrich]

Grab some extra jets and have a go at it. I think you'll find it's worth the effort. ;)

 

[levicp11]

read your manuel it says 95 or higher for octane i have a 06 i just blend some race fuel in pump gas

 

[gurt]

I have an athena cylinder on my bike that bumps up the compression ratio to somewhere around 14.5:1 and I can run 93 octane pump gas fine. I would do race gas but its $7 a gallon around here.

 

[Vinnie Lou]

Would adding Race Gas enhance a KX 65

My 9 year old son just started to race this year. He has a 2006 KX 65. Some of his friend's dads add race gas to their mix. I do not know much on this subject so I accept their opinions which seem to center on predictability. What I am additionally not sure of is whether :whoa: leaded or unleaded is optimal. We race at no higher than 1000 ft above sea level. Sunoco sells two unleaded types at nearby pumps (Sunoco 260 GT100) this is motor octane rated at 94 / research octane at 104. Not knowing much I wonder if this or any product is worth utilizing. Canned gas I see used at the tracks is often leaded. I wonder what race gas, if any, is more effective for two strokes .

As an aside, I wish I saw more concern in the MX community for the possible harm lead can do to children. There are no rules at the tracks concerning leaded gas and children are exposed to exhaust even when they are not racing.

 

[robwbright]

I wonder what race gas, if any, is more effective for two strokes.

About all I can suggest is to look at the following links and do a search on here for "race gas" or "race fuel". There are MANY factors to consider.

http://www.eric-gorr.com/techarticles/fuel_terminology.htm

http://www.eric-gorr.com/techarticles/Fuel_Basics.htm

And no, I've not seen any concern about the effects of lead on children. Perhaps Rich will have a comment on that. I wonder if the amounts are so small as to be negligible.

 

[AlwaysCool]

VP Racing Gas MS/SB 103 & 2004 CR250R

I run VP Racing gas SB-103 with VP MS-7 oil in my bike. I have a FMF Fatty pipe, FMF Shorty silencer, Boysen RAD valve, and an 8 oz Stealy flywheel weight. I leaned up the jets and my bike screams! By the way VP SB-103 is unleaded. But it costs like $8.00 a gallon.

 

[Rich Rohrich]

As an aside, I wish I saw more concern in the MX community for the possible harm lead can do to children. There are no rules at the tracks concerning leaded gas and children are exposed to exhaust even when they are not racing.

The aldehydes, acetaldehydes, and the air borne metals (mercury, cadmium, etc.) that are formed as a by product of ethanol based pump fuel combustion should a far greater concern to you.

If you want to keep your kids safe from this stuff you shouldn't bring them to any motorsports event.

 

[flat capper]

I run VP Racing gas SB-103 with VP MS-7 oil in my bike. I have a FMF Fatty pipe, FMF Shorty silencer, Boysen RAD valve, and an 8 oz Stealy flywheel weight. I leaned up the jets and my bike screams! By the way VP SB-103 is unleaded. But it costs like $8.00 a gallon.

how can you complain at that i just did a quick conversion and it works out the we pay the equvilant of $12 per us gallon for our standard pump fuel

 

[AlwaysCool]

Not complaining! Our regular pump gas is $3.00 here. I don't mind paying $8.00 for racing gas because I love the response from my bike with it!