I have a 2 year old John Deere Lawn mower with a Briggs and Stratton model 126T02 engine. It is still under warranty, but JD is not co-operating so I will fix it my self. The blade kept loosening up and hit the chassis and stalled the engine. I repaired the loose blade problem. It was a manufacturer's defect because of missing hardware. Anyway, the engine now runs terrible. It is hard to start and when I'm lucky enough to get it going it runs poorly....has a miss. Is there anything that I should adjust? I replaced the air cleaner and all of the simple stuff but I can't figure out how or what to adjust. These engines have no throttle control, no primer bulb, no choke control. I wish that they were built like years ago when you had these controls.

 

If the blade was loose & you had it running,, I'm betting on the flywheel key being sheared,, Pull the nut off the top of the flywheel & check it out.... Roger

 

I agree with Roger, sounds like a sheared flywheel key to me, to lock the engine so you don't break something, remove the spark plug, move the piston to the bottom of the stroke, now fill the combustion chamber with small rope like pull start rope, leave a little hang out, now when you turn the engine to remove the crankshaft bolt the engine will lock and nothing will get broke, when finished, back the piston off a little and remove the rope. Have a good one. Geo

 

Thanks, I actually thought of that today. The engine stopped suddenly when the blade hit the chassis. I'll bet there was enough angular momentum to shear that key. I will check it out next weekend. Can I get a new key at a hardware store?

 

You should get the correct B&S key .. Any small engine place will have them.. They should be a Buck or less & they are the correct material to prevent wrecking your engine next time you hit something....Torque the flywheel nut to 55ft/lb & you'll be fine,,,, Roger

 

That was the problem. Went out and bought an inexpensive wheel puller to remove the flywheel. There are two holes in the flywheel to accommodate the wheel puller. Only problem is that the holes were not tapped. Had to get a 1/4 -20 tap and cut threads. Worked like a charm.
Bottom line, the engine now starts on the first pull.
Thanks for your help here.