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Discussion Starter · #1 ·
Working on a friends T124 that won’t start after recent top end build. 10.8:1 pistons were installed. Stuggles to crank over with new battery and rebuilt stock starter. Checked pushrod adjustment and it was right.
Pulled spark plugs it turns over fine, checked each cylinder compression and they are185–190 psi. According to S&S it should be in the 140-160 ish range with the EZ start 640 cams the motor cam with. So popped the cover to verify cams haven’t been changed, which they haven’t. This cam plate is crazy beefy.
Before I try tearing this out what could be causing such high cranking compression compared to S&S specs? There’s no compression releases in the heads as the motor relies on the easy starts to spin over.

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That is not crazy high cranking compression for a 10.8, 124" S&S with 640 cams,, I see those numbers regularly with that engine/combo..
I suspect a starting system issue/s..
Check the battery voltage, then check cranking voltage, and the cranking amp draws. This will tell the story..
When you say, stock starter, rebuilt,, does that mean a stock harley starter? Did you test the starter draw, before you rebuilt it?
Accurate numbers are necessary when diagnosing all electrical issues,, all else, is basically wasting time, effort and money guessing what the issue is.
 

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Discussion Starter · #3 ·
Thanks Terry. He had the stock original starter rebuilt by an alternator shop. It still wasn’t right so he bought the Harley 1.4 starter from cvos. I slapped that in and was able to spin the motor nice with the plugs in or out.
Then with what seemed like a gallon of starter fluid was able to get it running so I think it was a combo of bad starter not spinning the motor fast enough and a vapor lock.
 

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Discussion Starter · #4 ·
Also after running for awhile I let it cool down and rechecked compression snd it’s down in the 125-130s so the releases on the cams must have been stuck from sitting but are free now which helps spin the motor even easier.
 
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