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I am having a small 2.5cc methanol 2-stroke engine that I am building an electric starter mechanism for. From my research I was under the impression that for a 2-stroke engine like the one that I have which is completely mechanical using a port for fuel intake it should not matter what direction I am starting the engine, it will just continue to move in that direction.

Image of the engine:

enter image description here

In order to make sure my DC motor used to start the engine is not suddenly "powered" by the much faster methanol engine I am using a one way bearing on the gear connected to the methanol engine. When I did a test run I could hear the methanol engine engage (due to the noise), but it cut out practically immediately afterwards and I could see kinda heavy abrasion on the gear of the DC motor (it is 3d printed, not some metal gear). I am getting the feeling that the methanol engine starts but wants to turn into the opposite direction of how it got started and then dies out pretty quickly because of the resistance.

This goes contrary to my believe that these 2-stroke engines should be able to run in any direction. What are the parameters that influence this for an engine and how would I go about determining that direction except ruining my starter gear and do it empirically? How does this work with a pull start, i.e. how do they ensure that the motor never engages in the other direction?

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    $\begingroup$ I have found some anecdotal evidence that RC engines always turn counter clock wise, however people failed to specify what direction they were looking at their engine and to explain why some RC planes worked perfectly well from both directions... However it is worth mentioning, that I was turning the engine clock wise. $\endgroup$ – Yanick Salzmann Jul 24 '20 at 19:22
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I have finally completed the starter mechanism for the RC engine (not the one in the picture, but a vertex .18 engine). I can add another anecdotal evidence, that the engine turns counter clock wise (seen from the front/output shaft). I could not get it started when using a clock wise starter.

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