February 19, 2018
September 24, 2018
Yes they are different - B175 had a larger diameter crankpin and the compression plates were crimped in position not secured by rivets as the D14.
the D14 sometimes spat the rivets sometimes wrecking the engine.
The original crank was revised in late 1968 with different rivets, side plates and flywheels (parts bulletin G54) and in 1970 BSA stopped reconditioning rivetted cranks and supplied ones repaired and modified to the latest standards (blue top service sheet 256 from April 1970). No details given as to what the latest standard was.
Hopefully your crank will have crimped compression plates.
April 30, 2012
But if you are asking if complete crankshafts can be swapped between the two models, then yes they can. My B175 engine has been running with a D14 crankshaft for several years now and several thousand miles. The reconditioned B175 crankshaft has now been fitted into my spare D14 engine which is now in my plunger frame off road bike, currently, and hopefully, being made able to go back onto the road.
1951 Bantam D1 125, 1970 Bantam B175, 1954 off road Bantam bitsa, 1995 Yamaha Diversion 900 and 2016 Honda Integra 750 scooter. Horses for courses, all very different to each other, but a bike for every occasion.
August 27, 2013
November 16, 2011
Very interesting thread. Factory memo states "transfer parts more accurately machined" , my brain actually read that as transfer ports to start with....is that they meant? Was the B175 cylinder also revised in shape externally, a complete new cylinder?
I wish I`d known about my D14`s flywheel cover rivets` crankcase machining capabilities back in the day 🙁 ....subject touched upon on here recently with SpacedMarine`s crank rebuild thread.
Glen, Wish me luck when I put one of my D14s on the market for the £2,750 you mentioned 😉 I bought it for £40 from my Dad in `75, no mate`s/family rates, unfortunately he knew I was often earning £120 a week!
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