QT50 - MJ50 question

Jimmy Cincinnati /
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So i swapped a MJ50 motor onto my QT50 and a thought occured. I used the MJ50 tranny but the QT50 CDI assembly (to make it more plug and play). It runs and idles but lacks any power. Is the timing different between the motors or would the CDI boxes have a different curve? FYI the motor was rebuilt with new oil seals, gaskets, and new top end. Oil injection was deleted. It currently has a stock carb, airbox, and exhaust but a 60cc bore kit. The carb was rejetted from a stock 72 to a 78 main. I used the MJ50 carb as the needle tapers were different.

last question, ive always been under the impression that the arrow on the piston should point down towards the exhaust port. The stock piston in the MJ50 had the arrow pointing up (towards intake) but the motor looks like it might have been tinkered with at one point. Anyone have advice on that?

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