This conversation started over in thread:
I thought that I would start a new thread discussing this issue and what I have learned.
First, why would anyone want to do this? Well, for me, I want(ed) to put a street triple 765 motor in a Gen1 Daytona that I already have. IMHO the 765 ST motor is a more usable for the type of riding that I enjoy, twisty roads. Since I don’t track the bike much due to the expense, a high revving engine is not a huge plus. I am much more interested in good mid-range power which was one the reasons I bought a triple in the first place.
So, you might ask why not just buy a ST 765 and that would be a good question. I took one for a test drive at my local dealer and instantly fell in love with the motor, but the looks of the bike are not to my liking. I still think that the Gen1/2 Daytonas are beautiful bikes; not sure what Triumph was thinking with the Gen3 bikes:-)
A couple of months ago I came across a ST 765 motor locally and pulled the trigger after convincing myself that it would physically fit in the frame which it does. I then started looking at what else would be required to make it work.
One of the first things that I investigated was whether I could make my Gen1 ECU work with the newer motor. I did a bunch of research and could not find anyone that had done this. I then remembered talking to JDGun a long time ago about a similar swap and reached out to him. He graciously agreed to a phone chat and downloaded a bunch of info that I was not aware of. One of the things that he told me was the CPS(Crankshaft Position Sensor) on the Gen3 motors is at a different different angle with respect to TDC. Since the ECU bases ignition timing on this angle, a different location would/could be a problem using a Gen1/2 ECU.
The newer ST motors use ride by wire throttle which requires the new ECU and wiring harness. This can be worked around if you fit the Gen1/2 throttle bodies to the Gen3 head which appears to work.
The Gen3 air box is completely different and will not fit in the Gen1/2 without modification. I was able to fit my Gen1 airbox and it appears to fit. Since the engine tuning is effected by the airbox geometry it would need to accounted for with a new tune.
The exhaust for the 765 is unique to the ST and will not easily fit a Gen1/2 bike. The header runs on the opposite side underneath the motor and would require a custom mid-pipe to hook everything together. Not impossible, but not plug-play.
And then there is the breather which is a totally different shape on the Gen3 than on the Gen1/2. I did not even think about this, but JDGun informed me that for it to fit under the gas tank it would need to be modified.
Some of the ins and outs are different, but these can be easily worked around.
So in summary probably the biggest problem is the ECU. The simple way to solve it would be to use a Gen3 ECU, wiring harness, and panel, but this could get expensive.