He's corrcet,we discussed this in another thread on the Murray forum..
I have used push mower engines on riders and home brews by using a cast iron pulley ,heavy enough to offset the loss of the blade's "flywheel effect"..most push mower engines used a 7/8" bore crank PTO,so you will either have to buy a cast iron pulley with a 7/8" bore,or it might be possible to get away with using an original pulley if it was 1" bore with a bushing ,as long as its heavy enough to let the engine start and idle normally..
I have cheated and used the original blade adapter to mount a pulley,but drilling two holes in the pulley to match the two that held the blade to the adapter originally..its critical to center it good ,and one disadvantage to this method is the pulley is way at the bottom of the crank,so it'll be nessasary to used spacers between the engine and its mount to jack it up,and align the pulleys so the belt will stay on..
If you use a 3.5 HP Briggs vertical shaft push mower,a cast iron flywheel off a similar horizontal shaft engine might fit in place of the aluminum one and work..
I once had a mini-bike with a 3.5 Briggs and I tried putting a push mower aluminum flywheel on it--it kicked back like a mule when you went to start it,and it was diffucult to get started and to idle below 1500 rpms--but once you got it going,it revved up quicker than a top fuel dragster!..thing felt like a 10 HP..for about 15 minutes,until the connecting rod turned into nuggets!..
I have used push mower engines on riders and home brews by using a cast iron pulley ,heavy enough to offset the loss of the blade's "flywheel effect"..most push mower engines used a 7/8" bore crank PTO,so you will either have to buy a cast iron pulley with a 7/8" bore,or it might be possible to get away with using an original pulley if it was 1" bore with a bushing ,as long as its heavy enough to let the engine start and idle normally..
I have cheated and used the original blade adapter to mount a pulley,but drilling two holes in the pulley to match the two that held the blade to the adapter originally..its critical to center it good ,and one disadvantage to this method is the pulley is way at the bottom of the crank,so it'll be nessasary to used spacers between the engine and its mount to jack it up,and align the pulleys so the belt will stay on..
If you use a 3.5 HP Briggs vertical shaft push mower,a cast iron flywheel off a similar horizontal shaft engine might fit in place of the aluminum one and work..
I once had a mini-bike with a 3.5 Briggs and I tried putting a push mower aluminum flywheel on it--it kicked back like a mule when you went to start it,and it was diffucult to get started and to idle below 1500 rpms--but once you got it going,it revved up quicker than a top fuel dragster!..thing felt like a 10 HP..for about 15 minutes,until the connecting rod turned into nuggets!..
