Outdoor Power Equipment and Small Engines - kickback on briggs 3.5 hp

I replaced a rototiller motor with a newer Briggs 3.5 hp. There is substantial kickback on starting. This new motor came from a lawnmower with same shaft and design.
Any ideas to eliminate kickback?

Hello pudsy01!

Do you still have the old engine? My guess is that the old engine had a cast iron flywheel. If you used a lawnmower engine to replace it with, it doesn't have the cast iron flywheel and that is the reason for the kickback. The lawnmower has a blade to add wight to the centrifugal force that is needed to prevent the kickback, so they just use an aluminum flywheel. Tillers have no blade slinging around to keep the turning momentum going, so they use a heavy cast iron flywheel.

Thks for the reply....you are correct and yes I changed over the flywheel with the old cast iron one. I still have kickback same as with the aluminum one. Next step is regapping ignition module to flywheel.

Any other ideas?

Thank you in advance

The first thing that comes to mind is whether the timing of the two flywheels matches one another. In other words, is the relationship of the keyway (in degrees) to the magnets the exact same on both? Is the flywheel key partially sheared? Are both engines the same style ignition? Whether it be point or electronic ignition. Kickback most usually indicates a timing problem.

Yes, both engines are same style with 2 leg magnetos. I put in a new flywheel key.

Do you have the proper gap for the magneto?
Model 95902 Type 3182 01 Code 95072052
3.5 hp B&S Classic.

Any other ideas/solutions?

Thks in advance.

The gap is .010", or the thickness of a business card or matchbook cover works fine.