thataveragebro
New Member
I have an option to buy a 73 cb750k running motor and I'm wondering if it will fit into my 78 frame? I'm open to any suggestions as well for other motors that might work!
Will a 1972-76 cb750k motor fit 78 750k frame?
- Thread starter thataveragebro
- Start date
DailyGrind
New Member
yes it will bolt in
thataveragebro
New Member
so im guessingg it utilizes the same frame for those bikes then?
DailyGrind
New Member
no the frames are a bit different year to year
thataveragebro
New Member
gotcha, just wondering since the mounting points seem to be the same comparing the frames on the two bikes.. but that's from looking at pictures.
Rider52
Over 1,000 Posts
The motor will fit. However, 77-78 bikes have a wider swingarm and corresponding rear sprocket carrier. You may need a spacer or offset drive sprocket to align the chain. Speaking of chain, the chain/sprocket size is different between early models and 77-78 bikes, 520 vs 530. You could change the swingarm and rear wheel sprocket carrier out for an earlier model. Both can be found easily. I did the opposite and put a 77 motor in a 75 frame, but used the 77 swingarm and rear wheel.
DailyGrind
New Member
the swingarm is not only wider but longer. also 77-78 main frames are longer and have 1 degree more rake in the neck. year to year minor changes, but the 77-78 is quite a bit different. motors all swap fine, pre 71 motor with a 78k head will make the most power. 520 conversion saves significant weight as a set and also increases driveline efficiency. recommend D.I.D. 520nz non-oring chain
