Mahindra 3510 engine popping noise

[crackshot]

I have a Mahindra 3510 3cyl, 34hp. After setting for a month we started it and it smokes out the exhaust and makes a loud popping noise near the back of the engine on the right side. It does quit smoking for a while the starts smoking again. Drained fuel and add 5 gal new with a fuel additive and ran it for about 2hrs. Still popping. 550 hrs. on engine. We did find a mouse nest in the area of the popping and cleaned it out. Oil ok, Air filter ok and radiator ok

 

[Offroadtek]

The fuel pump is on the right rear-ish. I assume noise varies with the RPM?

Do you have an Engine stethoscope? Or if your me, a rubber hose and big nail.