Racing Fuel

[airfreek]

Thanks for the input 123user.  Last year was my first season racing and i competed on a pretty stock 1st gen sv650.  This year I'll be racing a 749s that will fit into the stockish category and want to compete in the middleweight along with super twins.  I know its a little heavy and down on power compared to the current 600's so that's why i was interested in using some type of race gas instead of pump gas.  Right now my bike is at the ducshop in atlanta getting some work done to it.  So they are going to call me and give me some ideas as to what i should and i was looking for some other opinions.  Once again thanks for the advice everyone

[Super Dave]

The 749 might require a different fuel than an in line four.  The sheer size of the combustion chamber makes life different.  Think about it, each cylinder has more displacement than a GSXR1000 cylinder.  When they are pumped up, a bigger twin, the can require more octane than what one would need with a 600/4 etc. 

The Ducshop guys will have some good ideas.  Listen to them.  Use their prior experience to help you out. 

[123user]

If your trying to keep the costs down and don't need oxy-fuel, either VP marine, or Motorsport 98L are good options.  While the 749 has a significantly larger bore size than a 600, its still not enormous, the boundary area is significantly less than an RC51, TL, or 998-series.  Also, the combustion chambers on these are pretty good.  Any modern PentRoof type combustion chamber can handle very low MON numbers. 

If money is no object MR9 is good.  I ran some in my Duc at RA this summer.  Even with the old hemi-style two valve chamber (and 300F oil temps!) in ran great with no signs of detonation.  I'd be a little wary of using either MR10 or MR11 though, depending on the compression ratio.

I don't know if the S-model 749 runs the "Strada" cams (base model, shorter duration)  Still, many of the older (design)- desmoquattro headed bikes (748, 749, 888, 916) run larger duration cams than the testaretta.  The overlap typically reduces peak pressure significantly-  Long story short, any race fuel aught to work ok