I am wondering why you would need to tweak a LB engine? They are plently effecient for cutting the grass just as they are. Did you realize that the DF engine uses a tuned exhaust and a rear boost port?
I'm with you. If it is just cutting grass...well a properly jetted lawnboy or duraforce does it better that about anything else out there.
No reason to waste the time, effort, or even bother as they don't need the extra 5% hp or heat dissipation.
I would rather focus or obsess on one of the many other things I do that on...LOL
Now if you are using the engine for another purpose like so many Briggs were on go carts and mini bikes, then TWEAK TWEAK TWEAK away.
I was also, always the tuner who had his stuff running faster then the other peoples. Started with bicycles with sprocket changes and even rear wheels, then Puch mopeds with milling out exhaust port and opening up muffler, then motorcycles, then cars from 73 Buck Century with 350 2 barrel in it originally, to 67 and 68 GTOs with 400 Pontiacs.
I learned that if you opened the gap on the points to about twice as wide..It ran a lot stronger...until they burned up in about 10 days. But Standard Blue Streak lasted longer.
Learned how to tweak a Quadrajet and Carter ARF carbs. The air vane on GM is almost always to tight and jetting can be tweaked a lot after other mods.
Mowing grass is not something I do anyway. I fix mowers and test them for only a few minutes. As long as they run fine, I am good with that.
It never hurts to more fully understand how things work but there are times that "in theory" and in actual laboratory facts...things might be "better" but no real noticeable or worthwhile improvement in actual real world use.
Kind of like the old Splitfire spark plugs...."Up to 3.78% increased fuel mileage" if they did get full 3.78...that's an increase...sure is, but who really cares about that little bit. Were talking about 1990 when the mileage was probably 13-15 around town if lucky! I'm not going to bother to change them or pay 4.99 for them (autolite back then was .79-1.59) for the less than .5 mile per gallon....Not even if I can rationalize the savings if I keep them in for a little over a year and break even.
Cause in the real world...3.78% ain't gonna happen and if it does it will not maintain that level for long.
I actually use two in a KX750 Twin. They ran stronger for a bout 3 days and then about the same. That bike was cold blooded and popped and spit or about 8 minutes when cold. Put Bosch Platinum in and it started and idles smooth right at cold start. Not as powerful as with other or standard champions autolite etc but so much smoother on start up.
SO run run run that little lawnboy monster.
I stopped working on those around 2006 or 2007. I liked the duraforce last ones best. Hated the earlier ones with coils under flywheel IIRC and muffler under deck that clogged and needed exhaust port de carboned when they lost power. Never liked the rotating clicky throttle gov adj either. I guess I am nit wired for lawnboys because so many people love them.
I like the power and sound, but hate working on them.