Hi TJ,
Every little mod makes them more reliable, as we know most of these get dumped because
1 the base has rusted out
2 the float needle has stuck
3 it has lost spark or the spark plug has failed
4 it has been straight fueled
As for the bottom bearings failing I have only come across a couple and that is because once up and running there is a rumbling sort of noise.
To test these motors to see if they will run, I go through all the tests, check spark, check decomp is working, fit my test carby and see if it will fire, if not I then try with a squirt of starter fluid in the plug hole and then if I don't get any indication that it might fire I can then be fairly sure it has been straight fueled so I don't go any further with that motor, it goes in the dead PT pile and at a guess there is 50 in that pile at the moment
