My neighbor has a new looking, low hours 5hp Briggs Model 135202, type 0258-01, Code 96090640, on a small rear tine tiller. Many times when he tries to start it, the motor will violently pull the starter rope from his hand. This happens pretty often. If / when it starts it runs great. Any ideas.
thanks,
tony p

Check the key in the flywheel keyway, It is most probably partially sheared.
thanks,

I had a similar experience with a gas lawn mower. It turned out that the blade was missing which apparently works as a counter balance.

My neighbor has a new looking, low hours 5hp Briggs Model 135202, type 0258-01, Code 96090640, on a small rear tine tiller. Many times when he tries to start it, the motor will violently pull the starter rope from his hand. This happens pretty often. If / when it starts it runs great. Any ideas.
thanks,
tony p

I have had this happen on my 8hp Briggs, I figure it is due to the compression stroke of the piston.
Dean

There are 3 common things that can cause this on your engine

1. partially sheered flywheel key
2. your neighbor is not physically strong enough to pull the rope fast enough.
3. Too much valve clearance on the stems

Most likely 1 or 2, 3 involves a good amount of work to check and repair especially on your engine since it requires the gas tank and carb to be removed.

To check the flywheel key just unbolt the engine shroud (4 bolts 2 top, 2 bottom) and use an impact driver to unbolt the starter cup/flywheel nut. With the shaft exposed you should be able to see the slots on the flywheel and shaft as well as the key itself, they should be all lined up.

I had a similar experience with a gas lawn mower. It turned out that the blade was missing which apparently works as a counter balance.

A tiller uses a horizontal engine. No need for a counterbalance, thus the cast iron flywheel.