Well, thats a new one to me. Usually the phosphor bronze mixer body is harder than the brass poppet valve, and its the stem that wears, not the bore it sits in. Normally, with knowing what you’re saying, I’d have to suggest that somebody already replaced the poppet valve, but who really knows…..
Best I can suggest is if you need to repair the condition of the stem bore, make a tool guide that fits down and locates on the existing poppet valve seat, and hand ream the hole to the next nominal size. Obviously you don’t want to remove a lot of metal in doing so, thus it may be required that you buy a special size reamer that you might only use once in your life (a lot of my tools fit that description, it goes with the territory). MOst valve stems I see are 3/16″ (0.1875″) so if yours matches up with that, then reaming buying a decimal size reamer and carving it out to 0.200″ is not out of the question.
I make poppet valves out of standard 360 yellow brass, and in one piece. Most common seat angle I see is 30 degrees.
Hope it helps.
Best,
PM T2
Thanks for the timely information. I have piece of brass laying out now,
and a diagram drawn up with dimensions.
It looks like the valve guide will need reamed out to .200 or even larger.
A #8 drill bit (.199) almost starts in the hole, and the next size
smaller falls in and is sloppy.
The valve and seat are ground at 45 degrees on this one.
I have an old valve grinding machine to fine tune the face after
it gets off the lathe, but not sure it will chuck up a valve stem as small as I need.
Going out to the shop to see if I happen to have any reamers the right
size, but might start “roughing” out the new poppet valve…… first one
might be for practice anyway!
When I went out to the garage yesterday morning, I found out I had
a “senior moment” the day before, and left the fuel supply valve “on”
overnight, and had a big puddle of gas on the floor, gas dripping out
of the muffler, cylinder and crankcase as well.
I have the motor half apart, drying it out, so decided it was a good time
to address the poppet valve. Perhaps the old sloppy valve wasn’t seating
too good, but when I lapped it in with valve grinding compound originally,
it looked okay.
Thanks!
Prepare to be boarded!