Power/Starter problems!!!!

[amtraker0617]

I have a lawn mower with a B&S 42A707 1238 01 engine. I have replaced the battery 2 times in it and done usual oil changes. Every time i go to start it, its like it doesn't have enough power to turn over. I have tried multiple things to get it started like, jumper cables straight to the car, battery chargers and what not. Sometimes it works and i can mow my lawn, but most times it doesn't and i borrow a neighbors mower. I have hit the starter with a hammer and sometimes it helps. Is my problem something bigger than just changing my battery or attaching an external power supply? Today, with jumper cables attached to the mower battery, i touched the other 2 ends together and they sparked, so that tells me that my battery is holding power, for the time being. Could it just be my starter? If so, how to we know for sure before spending lots of money on this old mower. Thank you.

 

[ILENGINE]

if you have hit the starter with a hammer, you need a starter now, even if you didn't before. From the model number that sounds like a L head opposed twin. I have seen more than one case where the starter will get weak, and will turn the engine over, but not fast enough to start it. Almost like it is dragging.

 

[MRCo.]

If you replace the starter and still have issues, maybe look in to your cam decomp being bad.