Hi.
I bought one of the Eachine Chinese horizontal hit n miss engines and found it ran well right out of the box. I ran it on lighter fuel and on ordinary petrol/gasoline with a little 2 stroke oil and manually oiled the moving parts aside from the cylinder bore.
The thing ran faultlessly off and on for demos, running maybe ten minutes at a time. It started very easily just needing a flip of the wrist, after priming with fuel by covering the air intake ad turning the engine over a couple of cycles and then gently holding down the inlet valve a little while spinning the crank a couple of turns. I could just about guarantee that it would fire first flick after that......
Now it won't run at all. I have changed to fresh fuel, checked the mixture screw, changed the batteries for known good (measured voltage). I have good compression and the timing is undisturbed. I did a visual check on when the little flywheel magnet comes to the Hall Effect sensor and it looks like it is there at TDC on the compression stroke, or thereabouts and the disk which holds the magnet for the sensor has not been disturbed and is nice and tight.
The exhaust tappet has the correct clearance.
The spark is not that great. A little thin I would call it and there is some carbon on the nose of the plug, but I have cleaned it up somewhat with an old toothbrush and dish wash soap - then rinsed and dried it. The spark is there, but like I say not that strong. I'm wondering if the spark fails under compression - this can happen in a full size engine I know. If I test for spark just with the bare HT lead held near the grounded parts, I get a spark, but not great.
Is there any history of the second generation engines having bad spark units? I know the earlier ones had badly wired - no earth ht units which failed all the time, probably because the ht earth return may have been going back through the hall effect sensor.
All wiring is correct and undamaged and terminals are suitably tight.
I would appreciate any advice and experience of solving problems with this engine that any of you have had. I am not inexperienced with trouble shooting full size engines so I think I have checked all the obvious pitfalls.