12.5 HP B&S

[chops59]

G'day All,
I have a 1998 vertical 286707 L head 12.5 hp briggs on my Husky ride on, which was smoking pretty bad & consequently I've stripped it down to install new rings etc etc..for a 20 year old plus engine, there's not much wear & tear in the guts.
This am, I've put the crankshaft back in (new oil seal flywheel side) & connected the piston etc but I've noticed there's s bit of a clunk when I turn the crankshaft over by hand, which from where I can see is coming from the back counterweight. The whole counterweight structure has a bit of give, couple mm, but surely there shouldn't be any clunk when the crankshaft turns? the bearing shells on the counterweights look to be ok if you can discount a couple of miniscule bits missing from the edges. The counterweight bolt is tightened to recommend torgue & the 'dog bone' arm looks to be in good shape..
This 'clunk' has got me worried..can anybody give me a heads up?
Cheers

 

[bertsmobile1]

Check the bolt holding the 2 counter weight halves together and double shek the shorrt cin rod.
Very common for them to come loose or the rod break
Results are not pretty .

 

[chops59]

thanks for your contribution
..the counterweight is a tight unit with the bolt tightened to torgue specs..the only movement is miniscule give on the crankshaft where it sits in the bearing shells of both counterweights..the clunk comes from when the whole shebang is installed in position with the piston in it's proper centre position...so is the piston con rod restricting the correct movement of the counterweights?? am I missing something? doing something wrong?