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  1. #1
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    Default Joe Hunt timing on Cone Shovel

    I just read through 20 pages of forum search related to magnetos and can't find an answer.

    Ive got a 79 shovel with a Joe Hunt 1296 mag with auto advance. I am not new to mags, my pan has a Joe hunt as well and that bike runs solid all the time, but it does not have the auto advance in it so this is where I am unfamiliar.

    History of this bike, ran great in stock form and had no issues with stock electronic ignition.(I don't need anyone telling me to go back to stock, save your breath and smartass replies). I ripped it apart and did the top end and cleaned things up, and installed solid lifter conversion.

    push rods are good, cam timing is good, carb is in the same configuration it was when I tore the bike down, compression is good, points gap is good, plug gap is good.

    followed the Joe hunt directions to a T, which are strangely similar to the directions for setting a pan mag without auto advance. I got it started after a little time figuring out the timing. Got it to idle well and it sounds good, not pinging or back firing but as soon as I roll on the throttle it starts spitting through the carb and popping. Not the typical intake leak spit back, this sounds like timing to me.

    My question is, do you set these Joe hunt mags with auto advance to the timing mark line or to the TDC dot?

    In my monkey brain I reason that if youre setting a mag with auto advance to an already advanced timing mark i.e. the timing line on the flywheel, then the auto advance will be pushing too much advance and make it spit back through the carb.

    Any help and experience is appreciated.

  2. #2
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    In my opinion, the only way to reliably set the timing on your combo is with a strobe timing light, and setting the full advance timing. Anything else is just guesswork.

    My 2c only,
    Jim

  3. #3
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    Default

    You can static time it and get really close with using Morris's Katt Buzz box ...



    To peak the timing "Power Time the Scoot"

  4. #4
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    Quote Originally Posted by JBinNC View Post
    In my opinion, the only way to reliably set the timing on your combo is with a strobe timing light, and setting the full advance timing. Anything else is just guesswork.

    My 2c only,
    Jim
    So static time and get it idling well and use the strobe gun. Do I want the timing line matched up with the strobe at idle (950ish RPM) or when I bring the RPMs up (say 2000RPM)?

    Im familiar with setting advance timing on a car because its got the degrees and you can see the damper with the notches on it. Not so sure on a shovel.

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    Quote Originally Posted by KeystoneHate View Post
    So static time and get it idling well and use the strobe gun. Do I want the timing line matched up with the strobe at idle (950ish RPM) or when I bring the RPMs up (say 2000RPM)?

    Im familiar with setting advance timing on a car because its got the degrees and you can see the damper with the notches on it. Not so sure on a shovel.
    With the timing light, you look for the advance mark on the flywheel to come to a steady (full advance) position in the timing hole. Centered is 35 BTDC on big twin flywheels. The hole is 8 wide, so the front edge of the hole is 31 and the rear edge is 39. Yes, about 2000 - 2500 rpm, all the advance should be in.

    Jim
    Last edited by JBinNC; 08-06-2022 at 2:11 PM.

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    Quote Originally Posted by JBinNC View Post
    With the timing light, you look for the advance mark on the flywheel to come to a steady (full advance) position in the timing hole. Centered is 35 BTDC on big twin flywheels. The hole is 8 wide, so the front edge of the hole is 31 and the rear edge is 39. Yes, about 2000 - 2500 rpm, all the advance should be in.

    Jim
    Got it. Thanks for the help.

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