Of course, Brents list is perfect
Check ignition first (fast thing to do, but i guess its not the prob)
Check carb (fast thing and if it responds to your adjustments and the
spark-plugs look ok, the carb should be ok too ).
From your info i guess most important point on that list should be:
- Radiator tubes clogged.
As there is no good test for the radiator-flow:
Dont struggle to buy a new HD radiator ( and keep the old one )
Let us know about ...
Best regards
Christoph
radiator of my car looked really nice, car overheated while running
fast or running uphill. After changing the radiator, it NEVER again
overheated and it could even run without fan....
running with wrong timing reduces power, and for sure it will produce
more heat, but i guess it wont overheat once the radiator is good.
Bad news - lots of work to change the radiator