race fuel?


24 replies to this topic
  • 642MX

Posted April 20, 2009 - 02:04 PM

#21

Sorry to hijack the thread, but was the 13.5 a big change?


I think this thread needs hijacked....hahaha

Yes, the 13.5:1 was a big difference. It makes the bottom end and mid-range real strong. The top end stayed about the same. I liked it, but I thought the big bore kit with the 13.5 would be too much, so I went back with the 12.5. Sometimes I kind of wish I had the 13.5 w/ the big bore, but its got more power than I can manage now.

  • TIG88

Posted April 20, 2009 - 02:09 PM

#22

Thanks alot! I just redid my top end and went with a 12.5. Kinda wished I woulda gone with the 13.5. Ohh well!

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  • nickeenoo

Posted April 20, 2009 - 02:36 PM

#23

I just got about 40 gallons of VP for free (not sure what formula and I'm not where I can look). To be honest I can feel no difference at all. The bike doesn't seem to run cleaner/crisper and I don't seem to have any more power than I did before. Although my bike did run quite well without the race fuel. I did not rejet. The exhaust does smell good.

If it were me I wouldn't be running it unless it was free (which it was).

  • grayracer513

Posted April 20, 2009 - 02:41 PM

#24

Most guys can get by with 93 octane with a 13.5:1 piston. I used race gas when I ran a 13.5:1 because of a little pinging in hot temps (I probably could've used 93 without issues), but I didn't. I'm back to 12.5:1, but with a larger displacement... its smoother, more broad, and its happy on 93 octane.

I'd have to agree with that. Low altitude and high temps work against you on this, and at sea level in the summer, 13.5:1 on pump gas is right at the edge, especially if you find yourself in a higher than ideal gear a lot, as I do. But if not, and/or you ride mostly above 1000-1500 feet, 92-93 should be plenty.

  • 642MX

Posted April 20, 2009 - 04:09 PM

#25

I'd have to agree with that. Low altitude and high temps work against you on this, and at sea level in the summer, 13.5:1 on pump gas is right at the edge, especially if you find yourself in a higher than ideal gear a lot, as I do. But if not, and/or you ride mostly above 1000-1500 feet, 92-93 should be plenty.


Gotta love Southern Indiana. Pretty much 0-400 feet, hot & humid summers. :p





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