Originally Posted by Peter Gee

My parts book says my pump should be E3878, then in 1968 it's E6928, in 1970 E9421 and so on. Which models will fit my 1966? Can't find E3878 new or second hand for the life of me..the others, yes.

I have pump plungers (a) Scavenge 0.487/ Feed 0 .374 and another pump (b) scavenge 0.436 /feed 0.374---this seems to be correct for my year 1966 according to the Workshop Manual 650's up to 1970 and must be the mysterious E3878?


650/750

'63 - '66, E3878 (Scavenge 0.437"/ Feed 0.374")

'67 - 'early' '69, E6928 (Scavenge enlarged to 0.487"/ Feed 0.374")

Late '69 - '79, E9421/ 70-9421 (Scavenge 0.487"/ Feed enlarged to 0.406")

'80 ->, 71-7317 'double check-valve' pump (same 0.487"/ 0.406").