[gman2304]

My brotherinlaw has a JD/ JS63 that knocks on start up but smooths out pretty much at the governed speed. I took a look at it today and the c-shaft pin was sheared, so I replaced it and buttoned it back up and it still has the knock on startup. I'm thinking the c-shaft might be bent. If you guys have any advice or opinions they are greatly appreciated. Thanks

 

[rayjay]

You could remove the sparkplug and remove the blade and have someone rotate the crankshaft while you hold something near the tip of the crank stub to act as a point of reference to see if the stub is wobbling. Now if you happen to have a dial indicator and a magnetic base you could really see what's up.

Probably just a loose rod. My pushmower also knocks and smokes on start up. I'll run it till it blows. Actually, now that I think about it...It's been knocking and smoking less since I topped up the oil level with some Delvac. Maybe I should change the oil

 

[donmac]

check the motor mounting bolts. I had one I swore the motor was fubared but it was just loose!

 

[gman2304]

Thanks guys but after checking a little further it ended up being... a loose blade! He's not one to keep up with his OPE. He said he had stopped using it last year when it started knocking. Good thing!!! Thanks again