Here i’m explaining the difference between the briggs 11 horse (model 252707 and the briggs 12 ( 281707 ) or 12.5 horse, this case a 12.5 (model 286707). the only difference is the length of the stroke, the model 28 has a longer throw. both engines use the same piston, rod, rings ( depends on bore type ), and camshaft. The valves are different, the model 25 has short valve stems. The block has to be ground here and there, and the cam shaft may have to be ground so the rod won’t hit it. My 11 horse ( i have 2 but they are both the same ) are not the I/C series and do not have cast iron sleeves, so they do tend to wear out faster, but are good engines, and can be bored and sleeved. And a popular trick is to take the head off the model 25 and put it on a 28 block to boost compression and get a little more power out of it. My main point in the video was to talk about how you can take a 25 block and 28 crankshaft and make a stoker out of it, a 28 cubic inch engine in a 25 block. but there is a lot of maching to do in order to get it all to fit right. And a custom connecting rod would have to be made, which i do plan to make and sale in the future. and you also have to switch out the dog bone rod on the synchro balancing counter weights to the one that comes on the 25 crank because the holes are different sized that go in the block. Which on any racing engine it is best to eliminate the synchro balancer and either use the brass counter weights or upgrade to a 28 crankshaft with built in counterweights, already balanced and everything. a project for a rainy day!!! or a rainy week!