what happened to this head?

[Gabriel]

...and would you still use it?

Mid 80's 200s. It looks like a small screw got loose in there. BUT there's no mark on the piston so I'm assuming it was rebuilt at some point. I'll have to tear it down further to know.


254805


It was running just fine when i pulled it to cannibalize some parts. There are NO raised burrs anywhere. It doesn't appear to have affected any sealing surface. It's very unsightly though.

[rdlsz24]

Most likely a broken valve that bounced around. The valves and piston have since been replaced if they don't have matching marks.

Rob

[Gabriel]

If you look close it looks like a small Phillips head screw got in there.

Some really great news though. It WAS recently rebuilt.
It has a dome top piston. Cannot find a maker name but there are serial numbers.
Almost zero carbon build up. The inside of the piston is sparkling.
The bore is 66mm and i can still see some faint cross hatch marks from honing toward the bottom.

This is great news for me. I have another 200es to overhaul and this saves me a lot of money.
I just need to track down a 200r cam. Lol!

I'll use the ES head so i guess i will just tuck this head away for another day.

It also has a copper head gasket. Im half tempted to reuse it. I won't but im tempted.

[Shep1970]

I’m guessing a “China carb” butterfly screw came loose. In the engines previous life maybe. Check your carb flapper:)
254806
Shep

[Gabriel]

I think youre right.
It had a china carb when i got it. It wouldnt take shindy parts so i slung it in the trash.

[Rob Canadian]

I’m guessing a “China carb” butterfly screw came loose. In the engines previous life maybe. Check your carb flapper:)
254806
Shep

Ding, Ding.
Seen and heard of this many times

[Gabriel]

The real question, would/could it ever pose a problem?
I think no but I'm far from being an expert.

I have a lapping plate i made years ago from a peice of D2. Its heat treated to 62 rockwell and blanchard ground.
I was thinking of using some fine lapping compund and some transfer fluid to be sure its flat and then using it in the future.
Thoughts?

I know it works for a Briggs head. I've managed to lap those well enough to seal with no gasket to bump compression.

[Rob Canadian]

First you would want to see if the valves are sealing. Several ways to do this. My self I would prop the head up and poor a liquid (I use gas) down the intake runner and see if the intake valve is leaking. Do the same with the exhaust.

If they are sealed up ok then that is good. I would still pull out the valves and inspect.

Also clean up the head a bit to get rid of the sharp edges. Prevents hot spots.

I am sure others will chime in with more advice.

[El Camexican]

The piston that was in there when the screw went through must have looked pretty nasty.

I'd remove the valves, check they were repaired properly, then just remove any sharp edges inside the combustion chamber with 220, or 240 sandpaper and maybe a second scuff with a finer grit if you feel like it. Get rid of the high spots and don't worry about the low spots. I doubt that on that engine they would ever cause relevant hot spots. Then do the surface lapping that you mentioned, or it might be easier to just let a machine shop take off .020" or .030" to clean it up.