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    Default Spark plug reading for a big twin flatty

    Click image for larger version. 

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    So pulled my plugs after 1000 miles. Looks one has some peppering or "diamonds" attached to it. Please see the pics.

    I'm running ngk bp8es plugs in a flathead with around 6.5:1 compression. CV carb with 5 shims under the cv performance needle. Checked intake, no leaks. Ebeyond2000 ignition that I suspect the timing mark on the rotor is off. Timing is at 32-33 degrees fully advanced (if the mark is correct). Just wondering what the old pros think.Click image for larger version. 

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ID:	106238 pics make plug insulator look white. It's actually a light tan.
    Last edited by montuckymatt; 09-09-2020 at 8:29 PM.

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    Somebody wake Tattooo up, here is a plug from a motor that is genuinely too lean.

    If the pic ain't lying, the bits you see on the insulator and strap are aluminum, so you have some serious detonation going on. (That aluminum is from the pistons.)

    Are you using some type of plug adapter to run that long reach plug in a flattie head, or is the selection of a long reach plug a mistake?

    You need to check the timing with a strobe timing light after the basic setting of an Ebeyond ignition. The paint mark on the rotor is too vague to be of any use besides the static setting to get the motor running.

    You need to stop now before you have to buy another set of pistons (the minor case) or beat the big end bearings out of the rods (the bad case when it comes to detonation).

    Jim

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    JB,

    Thanks for the reply. I've got ULR heads which use a modern plug. I never had the bits of metal till I switched to the ebeyond2000. So my timing is likely too far advanced causing detonation? I will pick up a timing light today. I will also add another shim under the needle.

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    Quote Originally Posted by JBinNC View Post
    Somebody wake Tattooo up, here is a plug from a motor that is genuinely too lean.

    Jim
    LOL Hell I'm awake...... Just letting you guys answer questions............ Been way to busy in my gardens and cutting my lawn.........

    Yes the plugs are lean as hell........

    Question...... What kind of heads are you running with long reach 14mm plugs???????????????

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    Quote Originally Posted by Tattooo View Post
    LOL Hell I'm awake...... Just letting you guys answer questions............ Been way to busy in my gardens and cutting my lawn.........

    Yes the plugs are lean as hell........

    Question...... What kind of heads are you running with long reach 14mm plugs???????????????
    I'm with you. I think he needs a short reach plug. That may be the crux of the problem.

    Jim

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    I'm running ULR heads from VT cycle in finland.

    http://www.vt-cycle.fi/url-cylinder-heads/

    They use the long reach plugs. They recommended ngk bp7es. I'm using a colder bp8es

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    Quote Originally Posted by montuckymatt View Post
    I'm running ULR heads from VT cycle in finland.

    That's exactly why I asked what kind of heads you were running............. Your plugs are way to lean........ Don't ride it anymore until you find our why.............

    Does it pop back through the carb any?????????

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    I posted I was using ulr heads that use modern plugs a couple posts up^^^^^. I will be parking it till this gets solved. No popping through the carb at all. Doesn't even pop on deceleration

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    Quote Originally Posted by montuckymatt View Post
    I posted I was using ulr heads that use modern plugs a couple posts up^^^^^.
    Yea I see that now but it wasn't there when I asked my question, it looks like you and I both posted about the same time.....

    That's fine those are very nice heads.....

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    Oh by the be sure and run some antiseez on your plugs if you have any, that will really save the threads on your heads..... Those heads get really hot.........

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    Quote Originally Posted by Tattooo View Post
    Oh by the be sure and run some antiseez on your plugs if you have any, that will really save the threads on your heads..... Those heads get really hot.........
    Will do! I've got some of the cooper high heat anti seize stuff. Thanks!

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