Mark@ny

My magnum 91 was starting to run poorly 1/2 way during a 10min flight sometimes even dead stick. Land check it out start right up same thing. When it got hot the valves were tightening up. Just needed a valve adjustment. Simple I set them with .002 ok- .004 not ok.
But this is what I found the exhaust adjuster had a crack in the threads need a new adjuster. Ok but Magnum only sells rockerarm assembly 30something dollars. I used OS adjusters #45061202 tappet screw F40-300 from Tower $5.80 and it worked better than stock as it features an allenhead for adjustment instead of screwdriver slot.

golf4two

Thanks, Mark. Especially for the part numbers. I have a Mag 91 so I'm sure the info will come in handy some day.

Mark@ny

I think Magnum owners will appreciate the upgrade of having Allenhead adjusters much easier to get an accurate adjustment. Otherwise great engine for the price as you already know.

Mikester

My Feedback: (1)

Thanks for the part numbers. They are good engines, I have several, but the parts availability is not good. A few months ago I broke an intake valve spring and couldn't find any anywhere. Rather than put the engine away I bought a new head assembly for an ASP .91, it fits perfectly and runs just great. The head was much more than a valve spring, but now I have some spare parts from the old head. I think the new head was around $35 or so, as far as I can remember.