Top end rebuild, to oil or not

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#1
What's the thinking as far as lubing things when doing a 4 stroke top end? My 2 stroke I put together dry except a bit of oil on the wrist pin and bearing. Should I just do the same thing as well as a tiny bit of oil on the oil ring and scraper and leave the cylinder dry?
 
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#2
I put a few drops of oil or some assembly lube on every sliding surface in my engines. I rub the cylinder down with oil as well. It's peace of mind. Some engines pump very little oil to the cylinder head and it can take quite a long time before the oil actually gets there.
 
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#4
I rebuilt an old-timey diesel once. It took 20 minutes to get oil to the rocker gear in all 6 heads. I'm glad I used assembly lube there. That's a little extreme, but it takes a good 30 seconds to get oil pressure to the head in my Yamaha TT225 and that's with a new oil pump. 30 seconds without lube is a long time, especially when you're talking about extreme valve spring pressures seen on MX 4-strokes.

Before I get attacked, the point of the story was to emphasize how restricted oil flow to the head can be and how long it can take to establish oil flow to the head after a rebuild. Of course, on our tiny engines we're talking seconds and not minutes, but we're also talking much greater pressures and a much greater potential for wear. Quite a bit of damage can be done in those few seconds.
 
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#7
when I said dry I meant not lubing the cylinder. I will oil up the valves and such. For two strokes I never oiled the cylinder.
 
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#8
Even on 2-strokes, I lube the cyilnder. It's peace of mind. It doesn't take much. The rings will scrape off any excess.
 

SFO

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#9
I have always done dry cylinder assemblies, It is what has worked for me. I do make sure the top end is oiling before initial start up. I spin the motor with an air wrench on the c/s nut while the top end oil feed banjo is cracked. I never start a motor that I haven't verified oiling on.