100 Octane Fuel
  • How did 100 Octane run in your 450x?

    Good
    2
    40%
    Bad
    0
    No votes
    Same
    3
    60%
     
    Total votes: 5
  • User avatar
    PhatFireMan
    Posts:10
    Joined:Sat Jan 28, 2006 7:21 am
    100 Octane Fuel

    by PhatFireMan » Fri Apr 14, 2006 4:28 pm

    Curious if anyone has run 100 octane fuel in their X, and if so...what was the difference in performance? What elevation/mods/jetting were you?

    At the Baja this is going to be the lowest octane available through my pit service. Since the X has a compression ratio of 12.0:1 I am thinking it may be "OK" with the 100. But I am sure someone in here has tried it and can offer some insight. Otherwise I may have to buy a pail of 110, cut it 50/50 with 91, and see for myself.

    Thanks! 8)
  • User avatar
    kmag
    Posts:4
    Joined:Sun Sep 18, 2005 8:22 pm

    by kmag » Fri Apr 14, 2006 4:50 pm

    Buy the 100 and cut it 50-50 with the 91. That should give you 95.5 which is more than enough for an X with stock comression.
    Kmag
    05 CRF450X
    02 XR70
    02 TTR125
    01 CR500R
    02 Gas Gas TXT280 Pro
  • User avatar
    slapshot44
    Posts:4
    Joined:Wed Sep 21, 2005 8:51 pm

    by slapshot44 » Fri Apr 14, 2006 8:01 pm

    ??? Am I missing something? My X runs fine on straight 91 octane pump gas.
    05 CRF450X
    Factory Connection Suspension
    Rooster Rad Guards
    Scotts Stabilizer, Rear Disc Guard
    Flatland Front Disc Guard
    Cycra Hand Guards
    Works Connection Skid Plate
    JD Jetting
    Twin Air Filter/Frame/Airbox Mods
    Garmin GPSMap60CS
  • User avatar
    uniped
    Posts:234
    Joined:Sun Oct 23, 2005 12:29 pm

    by uniped » Fri Apr 14, 2006 10:03 pm

    I have run 100 Vp since break in and had no problems bike runs great never had any valve/motor problems what so ever. I just got my stage 1 Hot Cam today. I pulled off the valve cover this evening every thing looks good so far. got the Easter thing going on all weekend so I may not get to work on it till next weekend. Am very excited to get her done and ride it. If the finance gods will it the JD jet kit will grace the carb as well. any way performance is great burns clean and smells so sweet.

    Scott
    ________
    MARYJANE
    Last edited by uniped on Tue Feb 22, 2011 7:31 pm, edited 1 time in total.
  • User avatar
    PhatFireMan
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    Joined:Sat Jan 28, 2006 7:21 am

    by PhatFireMan » Fri Apr 14, 2006 10:46 pm

    Buy the 100 and cut it 50-50 with the 91. That should give you 95.5 which is more than enough for an X with stock comression.


    ??? Am I missing something? My X runs fine on straight 91 octane pump gas.


    You guys are missing the point. When I pull into every one of the 10 pits during the Baja 500...the ONLY fuel they will have to put in my bike is 100 octane.

    You're not allowed to enter Mexico with any fuel beyond what is already in your bike's tank, so no option to provide my own fuel for the race.

    I am just wondering how this bike is going to run on straight 100.

    Thanks for the input though.
  • User avatar
    slapshot44
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    Joined:Wed Sep 21, 2005 8:51 pm

    by slapshot44 » Fri Apr 14, 2006 11:57 pm

    I did ask if I was missing the point...

    Phatty, I understand that you will be using 100 octane because that is what will be available at your pitstops. I am confused because I get the impression from reading your post that you may be thinking that the 100 octane is inferior to the pump gas you normally run? Or are you concerned that the 100 octane may damage the engine? If the bike runs fine on 91 octane kalifornia gasoline (usually a higher oxygenation mixture, resulting in a leaner burn), it will also run fine on racing fuel with a higher octane rating, and if anything it will run better. Really exotic racing fuels can cause issues in engines not designed for their use, but 100 octane shouldn't be a problem in an X. I would recommend running some in your bike beforehand to take care of any jetting changes you may have to make.

    You may even notice a slight increase in power, but extra octane rating doesn't guarantee extra power. A given engine design will "use" what it needs as far as the octane rating is concerned, and any extra potential energy in the fuel is wasted. (There is absolutely no reason to spend big bucks on racing fuel IF your engine runs fine on pump gas.)

    12:1 compression sounds very high when compared to a modern automobile engine, but that is the static compression ratio. The cam profile greatly affects the dynamic compression ratio, which is what really gets you into trouble if you run low octane fuel in a "high compression" engine. So generally, the higher the compression ratio, the higher the octane rating of the fuel that you use must be. If you have a stage 2 cam, it is likely that the bike will not run very good with pump gas. Stage 1 cams may also be agressive enough to require higher octane rating. The issue you will have with racing fuel is that there usually aren't any stabilizers in it, and there also may be higher toluene content and other chemical enhancements that aren't very friendly to rubber parts and seals in the carburetor. This means that you don't want to leave racing fuel sitting in your bike long term. You will guarantee yourself carb issues.

    Man, have fun in Baja. BUT, if you hear the locals start making a lot of noise when you enter a section, watch out, there is probably some kind of booby trap set for unsuspecting racers. This advice comes from a guy I have talked to who has raced Baja several times...
    05 CRF450X
    Factory Connection Suspension
    Rooster Rad Guards
    Scotts Stabilizer, Rear Disc Guard
    Flatland Front Disc Guard
    Cycra Hand Guards
    Works Connection Skid Plate
    JD Jetting
    Twin Air Filter/Frame/Airbox Mods
    Garmin GPSMap60CS
  • User avatar
    -r0b-
    Posts:76
    Joined:Fri Jun 10, 2005 8:16 am

    by -r0b- » Sat Apr 15, 2006 7:30 am

    excerpted from Motorcycle.com


    The real advantage of racing gasolines comes from the fact that they will tolerate higher compression ratios (due to their higher octane rating) and thus indirectly will produce more power since you can now build an engine with a higher compression rati o. Also, alcohols burn cooler than gasoline, meaning even higher compression ratios are possible with them, for even more power.

    The bottom line here is that, in a given engine, a fuel that doesn't knock will produce the same power as most expensive racing gasolines.

    However, it sometimes happens that when you use another fuel, the engine suddenly seems to run better. The reasons for this are indirect: First, the jetting may be more closely matched to the new fuel. Secondly, the new fuel may improve the volumetric e fficiency (that is, the "breathing") of the motor. This happens as follows: Basically a fuel that quickly evaporates upon contact with the hot cylinder wall and piston crown will create additional pressure inside the cylinder, which will reduce the amount of fresh air/fuel mix taken in. This important--but often overlooked--factor is described by the amount of heat required to vaporize the fuel, described by the 'enthalpy of vaporization' (H), or 'heat of vaporization' of the fuel.

    A high value of H will improve engine breathing, but the catch is that it leads to a different operating temperature within the engine. This is most important with two-strokes, which rely on the incoming fuel/air mix to do much of the cooling--even mode rn water-cooled two-strokes rely on incoming charge to cool the piston. For two-strokes a fuel that vaporizes, drawing a maximum amount of heat from the engine, is essential--the small variations in horsepower produced by different fuels is only of second ary concern.

    Also important is the flame speed: Power is maximized the faster the fuel burns because the combustion pressure rises more quickly and can do more useful work on the piston. Flame speed is typically between 35 and 50 cm/sec. This is rather low compared to the speed of sound, at which pressure waves travel, or even the average piston speed. It is important to note that the flame propagation is greatly enhanced by turbulence (as in a motor with a squish band combustion chamber).

    The most amazing thing about all this is that you can get the relevant information from most racing gasoline manufacturers. Then, just look at the specification sheet to see what fuel suits you best: Hot running motors and 2-strokes should use fuels wit h a value of "H" that improves their cooling, while more power (and more heat) is obtained from fuels with a high specific energy.

    By the way, pump gas has specific energies which are no better or worse than most racing gasolines. The power obtained from pump gas is therefore often identical to that of racing fuels, and the only reason to run racing fuels would be detonation probl ems, or, since racing fuels are often more consistent than pump gas--which racers call "chemical soup"--a consistent reading of the spark plugs and exhaust pipe.

    The article in it's entirety

    http://www.motorcycle.com/mo/mcnuts/rt-fuel1.html
    -r0b-
    Middle TN

    Lurker Extraordinaire
  • User avatar
    PhatFireMan
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    Joined:Sat Jan 28, 2006 7:21 am

    by PhatFireMan » Sat Apr 15, 2006 10:12 am

    if you hear the locals start making a lot of noise when you enter a section, watch out, there is probably some kind of booby trap set for unsuspecting racers. This advice comes from a guy I have talked to who has raced Baja several times...


    Thanks...that's good advice.
  • User avatar
    Bryce
    Posts:440
    Joined:Tue Jul 26, 2005 8:39 pm

    by Bryce » Sat Apr 15, 2006 8:04 pm

    actually race fuels can make more power and usually do but octane is not the reason it's what they blend in the fuel MTBE and others to raise o2 content the ting to remember is that very few fuels are just straight gasoline

    Bryce
  • crf450x
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    Joined:Thu Oct 13, 2005 11:16 pm

    by crf450x » Mon Apr 17, 2006 11:42 pm

    i run 101 octane i mix my own fuel and i have had no probs been running it in my bike for almost a year and i ride like 4 times a week each ride is over 70miles i noticed a big power increase especially when i put 94octane in my bike.
    She says If I go ridin one more time shes gonna leave me..Im guna miss her.

    Live to ride, Ride to live
  • User avatar
    PhatFireMan
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    Joined:Sat Jan 28, 2006 7:21 am

    by PhatFireMan » Mon Apr 17, 2006 11:44 pm

    Cool, appreciate the input. Just wanted to gauge the effect of running higher octane in my X.

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