[AT] OT- Briggs and Stratton valve clearance

[Cecil Bearden]

I would make a bet that the high speed and that vibration was a big 
factor in the valve recession.  Also, that cheap unleaded gas will give 
you a lot of valve seat recession.  I use only the super unleaded no 
ethanol in my small engines and ATV's.  My wife & I use about 12-15 
gallons a week in our ATV's checkiing cattle etc..
Cecil in OKla


On 6/23/2016 9:49 PM, Dennis Johnson wrote:
> Gary,
>
> Valve wear like what you describe are common on Brigg's engines. I have seen it several times. Not sure of the exact wear mechanism but my guess is that 3/4 of the wear is on the valve, and the other 1/4 is on the hardened seat.
> When you get  Brigg's that losses power when hot, that is the first thing to check.
>
> Thanks,
> Dennis
>
>
> Sent from my iPad
>
>> On Jun 23, 2016, at 9:23 PM, John Hall <jtchall at nc.rr.com> wrote:
>>
>> Maybe if that engine was built for leaded fuel, the lack of the "cushion
>> deposit" the lead used to leave has allowed for the seats and valves to
>> hammer themselves to the point you lost clearance?
>>
>> John Hall
>>
>>
>>
>>> On 6/23/2016 8:45 PM, k7jdj at aol.com wrote:
>>> Not a lot of traffic so I thought I would post a question about a 70's vintage  5 HP Briggs engine.  The engine is used on a plate compactor so it is subject to extreme vibration.  I made the mistake of letting someone else use it and got a report that the engine was running extremely fast and you couldn't adjust the speed.  Quick check and it was obvious the throttle plate had fallen off the shaft.  Not an easy fix but after a lot of bad language I was able to reinstall with a new screw.  The engine would not start.  It would try but just would not run.  I checked the compression and it was zero.  Pulled the head and discovered the intake valve was not closing completely.  Exhaust was OK but probably doesn't have enough clearance.  These valves are adjusted by filing/grinding the valve stem.  Not a big deal but I can not figure out why the valve clearance would decrease.  I can't imagine there can be enough valve/seat ware to reduce clearance nor the valve stem growing l!
>   o!
>> ng!
>>>   er so what am I missing?
>>>
>>> Gary
>>>
>>> Renton, WA
>>>
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