Is this rotor housing done?
 

Looks like it has been burning, or maybe the rotor was chattering? :o10: I will get some daylight photos tomorrow.

Wash that thing is some gasoline or something...
It does have weird markings.
Looks like it was burning a lot of oil?
Excessive premix?

Did it have high mileage?
The weird center clean "groove" is strange, especially after the exhaust port.
The apex seal might've been bending outwards, but this is only indicative of very high mileage motors with very worn 3-piece apex seals...

I don't see too much grooving from the triangle assist piece, so I'm kinda puzzled myself.


-Ted

If you divide the housing vertically, exhaust/intake on one side and the compression/ignition on the other, it looks like a lot of chatter on the exhaust/intake side. Try acetone to clean them up. Pros use it, I've used it; it seems to work well.

Answers in Red.

So, you think the burning is on top of the chrome plating and not a sign of the plating being worn off?

Off to the store I go.

Wow, that oil residue didn't come off with that much cleaning...
Previous owner using synth oil?

Yeah, the high mileage explains a lot.

What's weird is that if the residue was made by normal, mineral oil, it should've came off with all that washing...


-Ted

No, if the chrome plating were to have been worn or scrapped off, you would know it.
Chrome tends to flake and peel off.
You can feel it with your fingers (nails).
If you've ever seen high mileage 12A rotor housings, you'd understand what I mean.

The residue is definitely on top of the chrome surface.
The apex seal chatter has a lot to do with all that residue on the rotor housing...


-Ted

I've seen some of this type of crud on the surface before, you may not get it off of there with passive cleaning techniques like hot tanks and just being sprayed with penetrating fluid. You'll have to scrub at it. Don't use anything very abrasive though. I guess just try a clean cotton rag with acetone first and scrub hard, if that doesn't work you might try a really really fine sandpaper, but use it very lightly and ONLY on the stained areas. If you try sandpaper you might just sand a little bit then try the rag again to see if it just needed to be loosened by having its surface broken.

However, if there's a lot of chatter wear, which it looks like there may be, I wouldn't reuse it.

I am the only owner. I've had it for 20 years.

I hit it with the acetone and it took off some of the varnish, but still left the dull finish on the chrome. Pics later.

Pretty much what I was thinking.

This will increase the cost of rebuild by 1K. So, now I might as well go ahead and replace all of the marginal parts to have a fresh engine rather than a slight life extension.

First Pic is before acetone. Second and third are after.

Why? Are you only considering buying new parts or were you hoping to reuse apex seals and such? I found more than one pair of pretty good housings for under $200 per pair.

Oh? Are you referring to 'store bought' used or from a private party?

Private party. Still, is your estimate $1000 for just housings or for other stuff, too? Regardless, it doesn't look like you have much choice. You may be able to reuse them, heck you'd probably be able to reuse a lot of housings that a pro builder would never ever reuse, but you'd sacrifice a lot for it.