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[m1ks]

A few more bits done, head (spark plug thread) is helicoiled.
Carbon scraped, flatted and polished with wet/dry and autosol.
Piston rings removed, oil control and middle oil scraper ring fitted upside down, the middle one you can understand the chance of getting it wrong, the oil control ring is stamped TOP on the errrrm top?
However, all looks good and clean, the bore, ring gaps in the bore, rings on the piston, (freely moving).
Just base gasket and another few gallons of black silicone sealant to scrape off, valves and decomp to finish lapping in and it's ready for reassembly, (without black silicone sealer).

So far:

Before:



After:

[m1ks]

I'd guess with the metal removed in the polishing phase i've probably increased the capacity to about 800cc?

[Craig]

Did My 350 2 years ago,
But I am ashamed after seeing you Engines insides..Clean enough to Eat off ! (after That Polish)

Mind you Some One did an article on Do Not Polish as A rough Surfaces aides Swirls in the Combustion chamber..in aide's Burn and Power... "Some whare"

I use (on And Off) Castrol valve Master in my (STD 350) and Though My Top End was a Bit Like Yours The soot/Carbon was Very Soft and Most Wiped/Scrubbed off easy : So I presume it was the Valvemaster? that kept it so..

Anyway 350's Great Bike.... Cheers Craig

[m1ks]

The carbon deposits on this one were fairly soft, scraped off easily with a 2p coin, (I used to have a flattened and filed copper tube specifically for this purpose years ago) Re the technical ins and outs of the polish / don't polish thing, I don't know, there may be something in it, but I always did my strokers this way and subsequent decokes were lots easier, it practically wiped off like soot, I never noticed any real deterimental effects but then I never went too mad or used a racetrack so it's hard to say.

[PeteF]

Craig, I think it's the inlet tract you shouldn't polish.

[PeteF]

m1ks, Nice job. I notice that your exhaust valve seat is recessed slightly from the dome of the head. Mine was the same and I was worried that there was something amiss. Perhaps they're all like that.

[Beezabryan]

On my 1992 Bullet valve seat recession was very noticeable. Had one head fitted with hard insert, the spare head has measurable recession of around 2-3 mm.