Hard as a Rock

[bikedelic]

Believe it or not, paint stripper works great! It cleaned a really heavy deposit off the top of the front piston that was maybe 3/32" thick, and it cleaned up the heads and intake valves very nicely.

Seafoam is also very effective and I do get a little bubbling when I put in on the exhaust valves but those deposits remain extremely hard. I am eroding them slowly but it's just not working well enough in this case. I suppose it is due the heat the exhaust valves are subjected to. I will continue to soak them, but a wire brush is in their very near future.

[redman24]

I have multi-speed dremmel tool with a number of tips and a precision brace attachment for touchy jobs. I have soft scrubby tips, sandpaper tips, wire tips and stone tips with various grit density. It has been effective for many small grinding tasks.

I even use it for the dogs nails on a slow speed. You should see the look in his eyes when I pull that thing out. I have threatened to use it on my wife's toenails as well.

[bikedelic]

Dave, Schmidtys, Scott, Do stock 91 Evo exhaust valve have some kind of ceramic coating on the face of them?

[SCHMIDTYS]

No. The exh. valves are Stelite but no special coating .

[bikedelic]

Thanks Schmidtys, I will post a picture later. I started sanding the face of one of the valves - finally got down to a bright spot of metal. There is a thick deposit of a ceramic-like material on the face of the valves, kind of tan or grey that sands without too much difficulty, but it's tough stuff. It looks like the only way to get it off will be to abrade it.

Interesting, what kinda crap are we burning.

[Dave63]

Originally Posted by bikedelic

Dave, Schmidtys, Scott, Do stock 91 Evo exhaust valve have some kind of ceramic coating on the face of them?

No.....that's burned on oil. It just looks like nitride coating.

[DevilDawg1]

Oven Cleaner, be careful what you get it on.