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  1. #1

    What octane do I need to run?

    So I just finished rebuilding my XPL. It was a Rotax 1050 before, and I replace the entire top end for a stock 951 cylinder and pistons. I have a Miller head with 47cc domes in it and a 6 hole base gasket. The compression is at 125 psi per hole with my junk compression gauge. I'm going to try a couple more gauges and see if I get any different numbers tomorrow. I'm not sure what the squish is set at right now. That's all the mods on the engine. So what do I need to run?


  2. #2
    GOO$E Mongoose2's Avatar
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    depends on the squish....

  3. #3

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    Agreed, anything over 175 is asking for a mix of 93/100 usually and 150 to 175 psi I usually run 93 to be safe. It's cheap insurance to a top end epically if your running wot often.

  4. #4
    Well I did some testing with better quality gauges today and got 147 mag, and 149 pto, The squish is .050. So what octane do I need?

  5. #5

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    Aint no way your squish can be .050 unless the suppossed stock cylinder was decked a huge amount. with a oem top end, 6 hole and that head you should be around .075 squish.

    TLR

  6. #6

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    How is it running?

  7. #7
    96XPSS's Avatar
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    Quote Originally Posted by TLR View Post
    Aint no way your squish can be .050 unless the suppossed stock cylinder was decked a huge amount. with a oem top end, 6 hole and that head you should be around .075 squish.

    TLR
    Oops! Someone got busted posting up a number without actually checking it...

  8. #8
    Quote Originally Posted by 96XPSS View Post
    Oops! Someone got busted posting up a number without actually checking it...
    Not quite sure what you're talking about?? I haven't had it running yet. I just got back from vacation and I need to go get some race gas.

  9. #9
    96XPSS's Avatar
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    Quote Originally Posted by codybrown View Post
    Not quite sure what you're talking about?? I haven't had it running yet. I just got back from vacation and I need to go get some race gas.
    Please read post #5.

  10. #10
    KrunchovXPL-GTX-RX's Avatar
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    That comp seems kind of low, though guages will be all over the place.

    With an ADA head and 50cc domes I have 155 in each hole and a 6 hole base gasket and unmolested cylinder gives me .073 squish.

    I run 93 in it.

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