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Discussion Starter #1 (Edited)
Its a long story, but I'll try to sum it up. This is a B&S 281707-0415-01 12HP engine for a riding mower from 1992.

My engine wasn't starting well and burning a lot of oil. First I replaced carb parts and cleaned carb. Soon I had a really hard time starting it, so I took it apart, replaced the piston rings (which were badly worn), lapped the valves, cleaned, and reassembled (with new gaskets etc) and proper torque values.

I was finally able to start it (with the aid of carb cleaner again) but much quicker. It is not idling well (but this is less of a concern for me). There is a faint sound (like metal-buttoned overalls in the dryer, but quieter). I ran it for 20 min in hopes that the piston rings would seat better. In addition to this strange clanking sound, I am getting gas in my oil (but only since I ran it for 20 min). I have had the gas hooked up for many days after putting it back together without any leakage into the oil.

Any ideas for either of these problems?

Here is the parts diagram if you are interested:
http://www.briggsandstratton.com/ma...e/docmanualdetails.aspx?showpdf=MS8987_LO.pdf
 

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Discussion Starter #3
I had thought about that, but the clanking seems to come from inside the crankcase, not the head, who knows though.

I would think that if that happened that there wouldn't be enough seal to get any compression at allor get some serious blowback out of the carb.
 

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Excess clearance on the valve lash could account for the noise, although it could have something to do with the counter weights. Worn bearings and link rod can result in a kind of knocking sound when the engine is running.
 

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Discussion Starter #6 (Edited)
The oil never had gas in it before, it was only after restarting it up this first time that it happened (after the rebuild). There is one counterweight in there with its link arm. I think that the knocking would have a heavier sound if it is was that. I'll remember that though if I end up taking the thing apart. It may be possible that the valve stems need to be ground down a bit. I forgot to check clearances between them and the tappets when I had them put back in.
 

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If your rings were worn enough to justify replacing them, then there is good possibility that there is wear in balance bearings and cams as well as the link rod. Not really a cost effective repair though. So it may not really matter.
 
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