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Thread: what fuel to use?

  1. #1
    Join Date
    Dec 2009
    Location
    Clovis nm
    Posts
    152

    what fuel to use?

    I have a pred with the big bore kit. high compression head. I took it out this week and burned a hole in the piston. The only thing different from the last ride was the fuel. I usually run 91 in all my toys but forgot and used 89. I have oil tank in place too.
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  2. #2
    Join Date
    Jan 2009
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    pa
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    269
    fule won't do it when its 91 to 89 your injection doesn't work or a crank seal went bad

  3. #3
    Join Date
    Dec 2009
    Location
    Clovis nm
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    152
    What is or where is the crank seal?

    Quote Originally Posted by bb49 View Post
    fule won't do it when its 91 to 89 your injection doesn't work or a crank seal went bad
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  4. #4
    Join Date
    Dec 2009
    Location
    Clovis nm
    Posts
    152
    I have had pistons burn up over octane levels but in cars not atv's. Does the mixing oil act like an octane? If it is just an oil for lubercation I dont see it burning a hole but if it also acts like a octane I can see it as the cause. I just want to understand the issue.
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  5. #5
    Join Date
    Nov 2002
    Location
    south carolina
    Posts
    2,784
    Post a pic of the piston if you can
    TS RACING
    Tanner Sorrow #12
    90 OPEN
    90 AUTO SENIOR


    Thanks to Tom and Atv 4 Play
    Thanks to Norris@ Quinn Motorsports

    2012 DURHAMTOWN BOMBER/PEEWEE 70CC CHAMPION
    2013 DURHAMTOWN PEEWEE 90CC CHAMPION
    2014 DURHAMTOWN BOMBER 90CC CHAMPION

  6. #6
    Join Date
    Dec 2009
    Location
    Clovis nm
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    ok I will have to do some work . I have been reading on 2 strokes and it seems the oil stays in the case and the gas evaporates as it hits the engine parts that are hot. Leaving it unlikely the oil will change the AFR. Leaving me to still thing fuel is too low of octane for the engine. I have also read some saying the oil lowers the octane of the fuel by 2 numbers but i cant see this happening as any ol produce will have a higher heat threshold than gas so mixing them will increase the octane levels as higher the octane the harder it is to burn. I have the new piston on the way. Now i need to figure out if the injection is working or just pre mix? I hope to not have to buy a new carb yet. The quad was ripping in the sand with my 240 lbs on it.
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  7. #7
    Join Date
    Nov 2002
    Location
    south carolina
    Posts
    2,784
    I would remove the oil injection and hand mix it anyway.There is no reason to have oil injection on there.You never know when it's going to stop working until it's to late.
    TS RACING
    Tanner Sorrow #12
    90 OPEN
    90 AUTO SENIOR


    Thanks to Tom and Atv 4 Play
    Thanks to Norris@ Quinn Motorsports

    2012 DURHAMTOWN BOMBER/PEEWEE 70CC CHAMPION
    2013 DURHAMTOWN PEEWEE 90CC CHAMPION
    2014 DURHAMTOWN BOMBER 90CC CHAMPION

  8. #8
    Join Date
    Dec 2009
    Location
    Clovis nm
    Posts
    152
    Agree. I may as well on both of my quads.
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  9. #9
    Join Date
    Dec 2009
    Location
    Clovis nm
    Posts
    152
    OK I removed the oil tank and pump. pulled the piston off. the cylinder does not looked scratched.. I found some metal behind the piston on the case. i sucked it all out. Not sure how much may have gotten into the case. I don't see a way to clean it or a drain plug to flush it. Unless i stand the engine on its end and flush it out that way.. I don't want to split the case if possible.piston.jpgpiston1.jpg
    If you cant beat it, Shoot it.

    2010 oultaw 90, CDI and PIPE.
    03 KFX 80 stock with 6''+ arms.

  10. #10
    Join Date
    May 2010
    Posts
    400
    holy molten metal batman !!!!!!!!!!!!!! lol.it doesn't look like it leaned out from the pics but maybe the death rattle did it in(detonation). we always used 100 octane with amsoil dominator and never had a problem.nastynotchback is right.dump the oil injection and premix it.the riders thumb will feel much better too.as far as the oil drain goes I've got one on our 06 preddy 90 so it should be there?? there's a small hole in a crossmember and it should be above that.by the way,what did the spark plug look like when you pulled it? was it intact?

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