Running backwards - for the engine without rotary valve there is no difference which way it runs. But there is a difference in the load. When engine runs backwards, the prop is running backward too. Prop is not symetrical, so it has different load on each direction. This is why the engine wants to start as a "pusher".

As for the glow plug, I tried my Poulan 25 with the new glow adapter (the one on the picture a couple posts above). As you can see the plug is hidden deeper in the adapter (about 3mm higher). What I noticed there is no difference in engine running. This is with AV8TOR fuel. Idles about 2100 rpm, without dying, but doesn't run smooth. Also does not respond to slamming the throttle like it should. After long idle (about 30 seconds) it would die when I open the throttle wide. It goes OK when throttle is advanced slowly. WOT rpm is about 7100 without missing.

Just by connecting the battery to the glow plug an idle increases to 2500 rpm. Closing the throttle more I can get stable 1800 rpm. Even after long idle (more than 30 seconds) engine responds immiedietly to WOT. On full throttle by connecting the battery rpm increases by 300 rpm peeking at 7400rpm.

The one wired thing is, when I open the throttle after ilong idle, the engine jumps to 7200 rpm and for the next two seconds or so it revs up to 7400 rpm. This is with glow battery connected.

So the last thing will be running the lean fuel to test how long will it take to burn the glow plug (glow plug will be powered all the time). But that run I will need to do at our field, not on my backyard (my wife is good for only 10 minutes of the engine run ). The bad thing is, that yesterday while flipping the prop backward (trying to start it by hand) I hit the groung with my finger (auch) - no more flipping the prop for next few days (the whole joint is swollen and hurts like hell). When I told my wife this was from hand-proping the engine, she though I got hit by the prop, not the ground