Peewee V4

Discussion in 'Engines From Castings' started by michael-au, May 11, 2015.

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  1. Apr 20, 2019 #221

    bluejets

    bluejets

    bluejets

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    40,000 is just a little bit unrealistic for what is being done here , don't you think?
    Even with wasted spark arrangement.
    I built a straight 4 cylinder 25cc that runs on methanol and glow which will turn 10,000 however rarely seen anything else that will get to that level.
    Usually a mass of spluttering much below that.

     
  2. Apr 20, 2019 #222

    Cogsy

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    Interesting, would you be willing to share the schematic for the ignition? I was basing my comment on some commercial ignitions I've seen with 12,000 sparks per minute upper limits (so only 6000 RPM for a 4 cylinder without waste spark).
     
  3. Apr 20, 2019 #223

    bluejets

    bluejets

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    Used to build these below in conjunction with others on the internet and although they worked quite well for my purpose, could never get much above about 14-15,000.
    Just couldn't get the charge into the cap with the circuit as it was.
    Have the code buried in a folder somewhere.
    Also possible to use without the uC with either points or hall effect.
     

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  4. Apr 20, 2019 #224

    stevehuckss396

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    Here's the problem with wasted spark on a 4 cylinder. Roy had CDI ignitions that could give 15,000 sparks per minute. On a 4 cylinder engine the ignition could work up to 7200 rpm. If you go with the wasted spark arrangement the ignition would be sparking double per rpm so the engine could only turn 3600 rpm before exceeding the max rating of the ignition. If you just trigger off the cam or distributor with magnets you could comfortably turn 5000 rpm without worrying about overworking the ignition. Also the current goes up as the rpm goes up so the battery will last longer because the amp draw on the ignition will be much lower. If you show your engines at the expo's that can make things much easier not having to worry about charging in the middle of a show.
     
  5. Apr 21, 2019 #225

    bluejets

    bluejets

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    CDI units, at least the ones I'm familiar with, draw next to nothing compared with conventional ignition.
    It is possible to have CDI's that will work quite well way beyond your 15,000 mark however, as I said previously, it would be way beyond that which we work with for many reasons.
    However both your and Cogsy's comments are noted and appreciated.
    Thanks.
     
  6. Apr 21, 2019 #226

    stevehuckss396

    stevehuckss396

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    Who makes one beyond 15,000. I would like to check into that.
     
  7. Apr 21, 2019 #227

    CNClick

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    There are many 250cc 4 cylinder 4 strokes from the late 1980's that rev around 20 000rpm with a waste fire system as the trigger is on the crank. The rev limit is not about the cdi technical limits, simply an industry standard agreed between Yamaha, Suzuki, Kawasaki, Honda to regulate power output.i had a FZR 250 with the limiter moved to 22 000rpm by my CDI gurru friend.
    Example Below


    Suzuki GSXR 250 1987 20,000RPM.

    Pardon this is the PeeWee thread so will refrain from more comments here.. That Pee Wee is very sweet, and sure many types of waste fire, crank trigger systems will also work fine on it.
     
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