Notes from my experience:
This motor is the simplest and smallest of all motors I worked with and I worked with more that 50 motors from 1.5HP to 85HP from 1961 to 1996 makes. But, I spent more time to make it run that on any of other motors I had.
I do not have explanation for that, because even with all new parts and great compression it did not want to start or idle or go high speed no matter what I tried.
Then after I almost gave up on it, it suddenly started to run fine and still does.
So, do at least this:
1. Important ! I replaced ground wire from armature plate to the head (even though old one looked perfectly good) with strong and thick wire soldering it to NEW clams (NOT JUST PRESSING IT WITH PLYERS!) and using electricity conducting grease on clams before tightening.
2. Make sure you use correct spark with correct gap. Take the spark plug out , ground it and try to spin (I use electric drill with socket to do this , do not use cordless because they are to slow). Do it in dark room to see if you get good strong spark. If not, then it is coil or condensor or wire or points. I always keep the set that I know works for sure to test replacing one by one.
3. If you have spark , check it with spark tester with proper gap. Sometime spak is there , but it is just not strong enough. If not , again: coil or condensor or wire or points, They can work, but be faulty to give good spark.
4. If you have spark and it is strong, check the timing. I use "wire method" and then after it runs - strobe method.
5. It does not have fuel pump , so it can be not enough flow of gas. I connect external gas tank to carb with good rubber hose and lift tank high to ensure gas flow to carb.
6. If this does not help, put gas into cylinder by removing spark plug and then try to start it. It starts , check carb float , something prevents it from opening.
7. My motor does not start well in START position. You have to pass START at least 5-8 degrees to get good start.
