HG42 problems/advice

[chrisvdv]

I am a Oliver 550 tractor owner, thinking of purchasing a local HG42.

The owner tells me it will fire right up and purr like a kitty but as soon as you put it under load it backfires, pops, and carrys on. He reckons a valve or magneto problem.

What does it sound like to you experts? Fuel line? Electrical? Or major work ahead? Many thanks in advance.

[hotratz]

I'd first clean and set the points and check to see what the timing is set at.
Sounds like a timing issue. It could be set properly but a sloppy magneto drive would cause it to backfire when loaded.

[VaMike]

Main jet may be plugged, or bad gas.
Best,
Mike

[Robert Barbour]

There is also a capacitor in the mag, if they go bad, they can cause your problem.