2 replies [Last post]
watson's picture
VBMWMO #9286
Joined: 05/15/2017
Posts: 58

We are working on a very sad 71 R75/5 that we want to remake as a shop bike and we are considering an engine swap. The engine in the bike needs a lot of work and a replacing it with something newer sounds interesting. Can anyone tell me if something like an R90 will fit into the R75 frame and mate up with the drive line?

Thanks, Doc

MikeL46's picture
VBMWMO #9300
Joined: 01/01/2016
Posts: 92
No problem. But, I would use

No problem. But, I would use the later 5 speed at the same time.



67 R50/2 w/R100 engine/trans and Ural Sidecar
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar

pokie's picture
Joined: 02/08/2015
Posts: 140
Engine Swap

The engines will swap straight across, no problem. The thing to consider is the numbers will no longer match. If and when it comes time to sell the bike (and yes, that time will come) prospective new owners will take issue with the numbers not matching.

On the transmission issue, I would stay with the four speed transmission, it is much more stout transmission. The earlier five speed transmissions were rather frail. Plus, having a useable kick start, in my opinion, is valuable. Again, if and when the bike is sold, having the correct transmission for the year may also be an issue.

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