Track day gas

Discussion in 'Information For New Racers' started by bsanorton, May 27, 2022.

  1. bsanorton

    bsanorton Well-Known Member

    So I had a great time this past weekend on my 1990 FZR400 track bike. I used ethanol free 89 gas. Should i be using something else? It has pods, and a slip on muffler, other then that I think she is stock
  2. Mongo

    Mongo Administrator

    Depends totally on compression.
  3. Cooter!

    Cooter! Well-Known Member

    The specs say 11.5:1 86.htm so it's not astronomical, but use at least premium grade 91-93. Whats the difference in cost/tank? A dollar? Less? Hot engines, hard use, all contribute to knocking/pinging and I doubt you can hear it on that ripper!

    You don't have any computer timing controls on it so if it's pinging, it is killing power and killing your pistons:eek:. Octane=insurance, you can't have too much, but over the top is wasteful.

    IMO, use good gas like VP and avoid the pump all together. Quality gas isn't that much more than the pump anymore:(. $6:89 for Shitvron mid-grade here, or $9:99 for VP 93 adds maybe $50 to a whole weekend of racing. And you get the cool-guy gas can collection, :crackup:.
  4. Michael Hausknecht

    Michael Hausknecht Well-Known Member

    You're fine with what you're using (assuming stock pistons and ignition timing). I didn't use race gas in my 400 superbike-build until I got the compression ratio up to 14:1. Higher octane gas burns slower, which is safe but at best, you won't go any faster and could end up with less power.
  5. Suzuka_joe

    Suzuka_joe Well-Known Member

    why not at least 91? probably adds up to $2 per tank..
  6. sheepofblue

    sheepofblue Well-Known Member

    Found an online manual and it says unleaded recommended. So I would think regular would work fine.
  7. TurboBlew

    TurboBlew Registers Abusers

    have you run the bike on a dyno to even see where you are at on fueling??
  8. Michael Hausknecht

    Michael Hausknecht Well-Known Member

    One can, but there is no reason to do so. Bump the CR or ignition timing sure, you'll want more octane, otherwise all it adds is cost and perhaps a nominally slower burn.
  9. Boman Forklift

    Boman Forklift Well-Known Member

    MR12 is only 87 octane.

    From everything I have ever read, and my old kart engine builder said he saw on a dyno, lower octane makes more power, unless you are detonating. Then you need more octane.
  10. SundaySocial

    SundaySocial Blue and Gold

    octane is to reduce knock.
    It slows the burn rate which can reduce power output.
    One of my mostly stock bikes (I drag race) runs noticeably better on mid grade, and is slower with premium.
    Next time you go to the track, buy a jug of good quality pump “mid grade” and a jug of “premium”.
    Empty the tank and start new and try to determine which makes it feel stronger/quicker. (Better) to you.
    The 400 loves revs so it may not improve with more octane.
  11. Cooter!

    Cooter! Well-Known Member

    I would caution against making tuning decisions based solely on the notoriously inaccurate 'butt-dyno'. Especially so for the minuscule-to-zero differences in grades of pump gas.

    Want better gas? Buy better gas. Octane ≠ quality.
  12. beechkingd

    beechkingd Well-Known Member

    The higher octane pump gas usually has ethanol. All but one place near me has 87 as the only ethanol free available. I would certainly run ethanol free in a bike=it's higher quality.

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