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We had the good stuff at the machine shop I worked at in the 70's. I would take a carboned-up head and put it in overnight, the next morning, clean as a whistle, no carbon, no paint, just rinse it off with water. No wire brush needed. We also had a caustic hot tank. Boss told me, "Don't ever put anything aluminum in there". Same thing with a cast iron head, pull it out, rinse it off, and all clean.

Here's how I did mine. Tightened the nuts a little at a time in the correct order. Then you can get a socket on one of the nuts on the back. Using a torque wrench, tightened it to 18 ft. lbs. Then put the 12mm box wrench on it and "felt" what 18 ft. lbs. feels like. Did the rest of them to the same "feel". 

Springs are available at Economy, Yambits and HVC, roll pin is a 3mm, I've never seen that cover piece on RDs.

Thanks for sharing, as far as I know I have the original porting. Will the bigger holes make a difference?

I think so, less of a restriction as it is inhaling.

They are all Mitaka pistons. This is the one to use if you want 65mm with the bigger holes. RZ piston. https://yambits.co.uk/rz350l-piston-kit-100mm-p-15912.html

Seal orientation and don't forget to install the clip on the gear side to lock it in place.

The factory manual says .04mm (.0016") but .05mm (.002") adds a little safety factor to prevent seizures. Bore it to a size that will allow the last .002" be done with a good hone to remove the bore tool fracture marks and be left with a good surface.

Looking good. I just got my RZ engine out and on the bench after years of neglect. Looks like it just needs new pistons. The crank looks ok, looks like it was rebuilt sometime before I bought it. I'm just going to replace the outer bearings. Power valve was cruddy and stuck. I still have the stock carbs and never was able to get a slight rich spot as it passes through about 5000 rpm to go away. The rest of my bike needs a full refurbish too, forks, brakes, and a new shock.

I have taken a seat lock or ignition switch to a locksmith and they made a key. Didn't need no stinkin' number.

I thought I better take a peek in there. I have 2 summers, maybe 1000 miles on these Wossner pistons running in my hot rod. The rings were shot with an end gap of +.030". Looks like they were starting some blow by. The pistons themselves measured about .001" smaller than new. That ain't bad compared to the Wisecos I had that would collapse a lot more than that. The cylinders are worn to the point of a bore job needed, .002" in some areas. The top part of the cylinder, where the rings ride is definitely worn even though the hone marks are still there. The area below the intake port shows how the piston skirt bangs away, especially when the bore clearance gets big (.005"). Overall, both pistons and cylinders look the same. I'm happy with how the Wossners held up. Crank looks great, it's not spreading apart on the ignition side, like has happened before. Ported, big reeds, 34mm vm carbs, hpi ignition, 25:1 Yamalube R, and loves going up to 9500 rpm.    

I think the 2.8 ohm reading is caused by, when having the wires all connected, you are actually getting a reading of 2 coils, that are connected in parallel, due to the +12 leads on the coils being connected together.

Yes, the side with the spring goes down into the tube when installing.

New 350 and 400 fork tubes seem reasonable. $150-$200 on Ebay.

That nipple plugs into the brass piece on the small end of the spring.