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Do all Dianas have a 'DM250M3' engraved on the motor - both 4 speeds and 5 speeds?

As far as I known only the 5-speeds have the DM250 M3 stamp. The 4-speeds just have DM250. Someone else my know more of different.
Tony

only the last Diana's with the updated kickstarter mechanism had DM 250 M3 stamped

Eldert

So, I'm assuming that the cam, pistons, valve sizes and ports in the 4 speed Diana were different than the 5 speed Diana Mark 3 and in a lesser state of tune. The carb was also not the same. Correct?

there where at least 3 diff Diana's with diff specs . the european Diana 4 speed with very mild camshaft and UBF24 carb .
and the USA spec 4 speed with the red camshaft and 27 SSI carb . the last Diana's had the Mach1 grey camshaft and 29 mm SSI carb .

Eldert

Eldert - Do you know if the valve sizes and port sizes were the same throughout the different Diana models? And was the compression the same? Thanks - Frank

US market (i.e. Berliner) early 4-speed Diana was same spec as the Monza: 37mm intake valve, 33mm exhaust, same compression as a Monza unless the kit piston was installed (see “Directions for the Overpowering”). The stock intake port was sized to match the ubf24 carb. There was a kit carb SSI27A with a manifold to fit this carb. The intake port would have to be matched to the kit manifold. The Diana MkIII 4/5 speed was delivered with the SSI27A carb, 36/33 valves and a 10:1 piston. These two are actually the only “Diana” models but Berliner advertising continued to confuse the subject by referring to the Mark 3 as a Diana in some ads. The Mark 3 has 40/36 valves, 10.5:1 compression and SSI29D carb with corresponding intake manifold and intake port. Matt