This manual should help you adjust valves properly. I adjust them as they say, then turn the engine by hand through 4 complete cycles and then start over to check them. If they are not within specs I start over and do everything again.
You need to try to find out why the push rod broke, they do not just break for no reason. IF it broke from the valve guide slipping, you still need to take care of that.
WLP here, Found the problem for the surging. Problem was a plugged jet. This was found on the sixth try at cleaning. It is located between the two adjustment screws. Air/gas, which on newer models will have a black cap on it, and the speed/gov. screw, that will have a philips head. On the older models you will see a brass plug that can be removed with a flat tip screw driver. After this plug is removed you will find three holes in it. Holes are very small and can be cleaned with a tooth pick and carb cleaner. Note; only one was pluged on my carb.
On newer models this is a round metal plug. This can be removed for cleaning but I have not done this.
Runs great now.
Did you make an effort to find out WHY the Intake push rod broke? Sometimes they wear thin where they ride on the fiber guide, sometimes they break because the valve guide has moved. IF that is the reason, you need to fix that. Valve guide should not be more than 1/8" above head casting. May be a little hard to tell with valve seal on it.
IF valve guide slipped, I have a fix. IF you want a Service Manual, I can send you one at address below, put in proper format and remind me engine model number and what you want.
