Briggs and Stratton Power Built 12.5 HP Flathead Model 28 Rebuild, Teardown / Reassembly PART 1

PART 1…. In this video i’m doing a teardown and rebuild of a Briggs and Stratton Power Built 12.5 HP Flathead Model 28 Lawn Mower engine. Hope this series helps you, be sure to watch the other parts. And the last part is the first start of this motor after being rebuilt (not a complete break in video, just the first few minutes of running and adjusting carburetor) The only thing i left out was checking the ring gap clearance, which all you do is put a new ring in the cylinder use the piston to push it down about a half inch or so and use a feeler gauge to check the gap on the ring. Use general safety rules when doing anything like this, it is extremely to cut/smash fingers at any point. I cut my thumb really bad on the timing gear on the crankshaft (off camera). Just be careful and use common sense. Thanks for watching



23 thoughts on “Briggs and Stratton Power Built 12.5 HP Flathead Model 28 Rebuild, Teardown / Reassembly PART 1

  1. Hello, I have rebuilt my engine its 12 hp  briggs and stratton, but cant geti to fire up now. I have a spark, even spark plug is wet from carb blowing petrol. I have aligned them to holes on top of gears as you showed, but them i am trying to fire it up it just spins. maybe i need to do something with timing? i tried to tip some fuel into carb straight and heard a bang, like it exploded in the carb instead of cylinder. i  can send you some pics or video, can you help me please? thanks

  2. I have rebuilt my engine but it still will not start petrol is blowing out of carb instead of being sucked in any ideas thank you

  3. Still goin'?  My connecting rod shattered and scored the crankshaft.  I'm trying to find an undersized connecting rod, but everyone just wants to sell me a new engine.  Got a good source for parts?

  4. Hey man great videos. I'm in the uk and have a problem with a similar engine. I've done a decoke and valve grind etc. Reset the valve clearances as per B&S manual but find that the inlet valve with a clearance of 0.005 at TDC doesn't start to close until the piston is more than half way up the bore on compression stroke. I haven't disturbed the valve timing but have checked that the two dots on the crank and cam are lined up correctly. Engine ran OK-ish before the work but seemed a little down on power.
    Any help would be appreciated.

  5. I've got a 8hp flat head briggs on an old snapper riding mower from the late 70s or so. Been in the family since new…anyway it runs surprisingly well but smokes like crazy, especially under load. In fact i'm a little surprised that it runs as good as it does and burns that much oil. I'm 95% sure it is one of the cheaper aluminum bore engines but i have not taken the head off to be sure. I originally thought I'd just buy a new OHV engine to put on it but they cost a lot more than I thought I would and they are quite a bit longer than the old flat heads and would require a good bit of modification to the mower to fit. Do you think it could be saved (or would be worth the trouble?) Can the aluminum bore engines be bored over or will it just self destruct? I've never had an engine completely apart but I don't think its going to live much longer as it is so I guess I don't have much to lose.

  6. Can you run that rectifier thing past me again? I just inherited one of these engines that was removed from the tractor and, while I see the wire off of the stator, I really don't know what it is supposed to plug into. I understand it charges the battery and I suspect it plugs into something (rectifier) but would like to better understand everything from that wire to the battery.

  7. i,m putting the same engine back together but when i tighten down the connecting rod cap bolts,you can barely turn the crankshaft…but when i leave the bolts can easily turn the crankshaft….wth is going on…dont know how the connecting rod bolts would have anything to do with turning the crankshaft….what is going on here??

  8. That Frank, he lives inside of his own heart. I don't know why you help us with these videos like you do, I just know I am SO THANKFUL you do it!

  9. It's this particular engine that I enjoy working on more than any other. So simple yet so well built. Always fun fixing these.

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