Valves

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  #1  
Old 04-22-05, 02:49 PM
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Valves

I have a B&S 10 hp, horizontal shaft m-19E412, t-0107-03, c-9512221A that operates a 5kw generator. I was reseating the valves when I noticed the seat width on the exhaust valve was very narrow...less than 1/32". Should I continue to cut at the valve seat to get it wider? The reason I got it was it would have a 'miss' in it whenever it got hot. Do I need to replace the seat? The intake valve is cut at 31 degrees and the exhaust valve is cut at 46 degrees. The valve seat on the intake valve is greater than 1/32".
 
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Old 04-22-05, 08:44 PM
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As long as it seats completely all the way around, you should be fine. The narrower the seating surface is, the better in my opinion. That's the reason people do double and triple angles on seats...to give the valve a thin area of contact for seating.
 
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Old 04-27-05, 11:33 AM
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Valves

Cheese, I completed the valve seating job and reassemblied the engine...still has the slight 'miss'. Before I disassemblied it again I ran a leakdown test on the engine and there was considerable air leaking into the oil sump, possibly leaking past the rings or a scored cylinder. The leakdown tester gauge was just barely in the red. When I first pulled the head off, I noticed the carbon on the head and piston was 'soft'. This time when I pulled the head off there was a good bit of oil present in the area. My question is, could an oil leak be causing the 'missing'?
 
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Old 04-27-05, 09:34 PM
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Not likely, unless it was enough oil to affect the spark plug. This would usually include lots of smoke. I think, given your description of the problem and the fact that you've done the valves, I would suspect ignition problems of some sort. Maybe a pinched kill wire (if electric start, check behind the starter. Coil kill wires often get pinched back here and cause misses when the engine warms up enough to soften the insulation on the wire). Also check for looseness in the kill switch and any bad spots on the plug wire.

Were the valve seats tight in the block?
 
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Old 04-29-05, 09:59 PM
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Get some SeaFoam. Put it in your gas & in the oil. Works damn nearly instantly when you use it. Most AutoZones & Napas seem to have it. If not, look for the SeaFoam deep creep.

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Last edited by cheese; 04-29-05 at 10:55 PM.
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