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Midknyte
Posted on Sunday, August 03, 2014 - 01:16 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Will an incorrect spark gap make a cylinder run super hot?

It's a dumb and rhetorical question. I expect that the answer is yes. I'm just kinda pissed about something and want a second opinion.

Thanks.
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Greg_e
Posted on Sunday, August 03, 2014 - 03:57 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

No, not really, at least not that I've ever noticed.
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Readyxb
Posted on Monday, August 04, 2014 - 09:43 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Same as Greg_e, I haven't heard that before.

The only way I could see temperature being affected is if the gap change somehow affected the dwell - the time needed to build a sufficient field in the primary windings of the coil to jump the gap. And requiring a longer dwell, if the circumstances just happened to work out, could in theory restrict the maximum amount of ignition timing/advance that could be used, which would affect combustion temperature if somehow not ideal. In other words, say you need 2 ms of dwell to charge the primary windings for a .035" gap. On an engine with 2 cylinders at 6,500 RPM and 30 degrees advance, there is enough time. But with a .045" gap, you might need 3 ms dwell, and maybe at max RPM and max advance, there isn't enough time to meet that "ideal" requirement. So to compensate, you retard the ignition timing from ideal to meet the required dwell. Having a retarded ignition from ideal would affect temperature. Note that these are just made up numbers for discussion purposes.

BUT... all this implies that the ECM somehow knew that the gap changed from the recommended value, which isn't the case. The Buell ECM does take into account battery voltage when calculating the dwell, but I don't think there is any other feedback mechanism involved.
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Midknyte
Posted on Monday, August 04, 2014 - 10:43 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks. It also occurs to me thinking back on it that it might be that my gas tank is probably near empty and there's no fuel to absorb the normal engine heat.

I do need to admit that I'm grumpy about some service I had done to it and need to resolve and I'm in that sour mood of looking for things to be wrong. The right side and airbox were super hot - more so then I ever recalled.

Thanks for the info on timing. Interesting info. They adjusted that and now the bike hesitates on start too. Never ever did that even after sitting winters.

Ugh.
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Greg_e
Posted on Monday, August 04, 2014 - 04:55 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Then they may have gotten the timing set wrong, and that could make it run a bit hot.

(Message edited by greg_e on August 04, 2014)
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