| March | — | 103 368 | intake manifold now has zinc paint |
| March | — | 103 990 | rocker studs larger diameter |
| April | — | 104 657 | different clutch lining |
| May | — | 105 095 | oil strainer studs now 8G hardness |
| May | — | — | BEGIN PRODUCTION progressively coiled valve springs, one piece lifters |
| May | — | 106 639 | progressively coiled valve springs |
| June | — | 106 836 | oil filler cap, now has copper clip |
| June | — | 107 859 | cam shape modified |
| July | — | 108 729 | one piece lifters |
| August | — | 109 307 | Oil cooler has perforated plate, preheat tubes larger diameter, fan housing is now wider, cylinder head intake ports larger |
| August | — | 108 601 | cylinder bore roughness changed |
| September | — | 110 673 | piston rings chamfered on inner edge |
| December | — | 112 939 | another rocker shaft modification |