Bad backslap from recoil starter

[greggw60]

Just put an older 8hp Briggs together. Mainly just needed cleaned up, honed and a set of rings and lapped and set clearance on the valves. Valve seats appear good. Starts and runs great but has a real hard place in the cycle just as the piston passes TDC on the downward stroke (power stroke). It rips the starter cord out of my hand. Checked the valve clearance twice and ruled out anything else I can think of. I can feel the tight spot in the same spot of the cycle when it's pulled slow. Don't think it's a bent crank since it's fine on the other cycles. I did do a hillbilly plane on the head and block deck with a piece of granite and wet/dry paper but can't imagine removing enough surface to mess up the valve clearance.? Stumped

 

[greggw60]

Just put an older 8hp Briggs together. Mainly just needed cleaned up, honed and a set of rings and lapped and set clearance on the valves. Valve seats appear good. Starts and runs great but has a real hard place in the cycle just as the piston passes TDC on the downward stroke (power stroke). It rips the starter cord out of my hand. Checked the valve clearance twice and ruled out anything else I can think of. I can feel the tight spot in the same spot of the cycle when it's pulled slow. Don't think it's a bent crank since it's fine on the other cycles. I did do a hillbilly plane on the head and block deck with a piece of granite and wet/dry paper but can't imagine removing enough surface to mess up the valve clearance.? Stumped

 

[slomo]

TDC on the proper stroke to set the valves? Light flywheel or no mower blade installed? Cam in time with the crank proper? Flywheel key okay?

slomo

 

[Scrubcadet10]

Let's start with the engine model and type numbers so we can see which engine you've got.

 

[greggw60]

Let's start with the engine model and type numbers so we can see which engine you've got.

BS 8hp 195414 1137 01

 

[greggw60]

TDC on the proper stroke to set the valves? Light flywheel or no mower blade installed? Cam in time with the crank proper? Flywheel key okay?

slomo

Yep. Horizontal. All been checked and rechecked. Starts right off and runs and accelerates smoothly. Just has that really tight spot I can't figure out. Pulled the rope till it got hard to pull and pulled the head off to see where it was sticking. Rolls over smooth with no compression

 

[greggw60]

Looks to have all original parts. Cylinder checked out well within spec. Seems to have been lightly used and cast iron sleeve

 

[greggw60]

BS 8hp 195414 1137 01

S/B 195412. I/C series

 

[greggw60]

Yep. Horizontal. All been checked and rechecked. Starts right off and runs and accelerates smoothly. Just has that really tight spot I can't figure out. Pulled the rope till it got hard to pull and pulled the head off to see where it was sticking. Rolls over smooth with no compression

Geez. That was a lot of pull

 

[Hammermechanicman]

You can remove the spark plug and turn enging slowly by hand to check for any nechanical interference. If no i interference and valve lash is good probably a decompression issue.