1964 250 Diana Mark 3

[DewCatTea-Bob]

" nothing happens until north of about 5.5K rpm "

____ The 'Mark-III' cam.model does pull somewhat harder at about that same point, but it's SURELY not anything so drastically notable (as if a power-knob had been abruptly twisted-forth).
At the low-end rev.range, a stock Mark-III is not very-much down on power than a Monza.
__ Perhaps if it still has a stock-cam, it may not be correctly timed to the crankshaft as originally intended. - (A retarded stock-camshaft may cause a more peaky turn-on towards the upper rev.range.)


Dukaddy-DUKEs,
-Bob