As other folk , I would be interested in what mishap the engine had
My 750 was bought from Rob on this forum, and he acquired it from a dealer, but the original engine had failed due to the oil pump chain breaking, and the dealer installed a 1990 RD04 motor he had, as it was cheaper than repairing the 650.
It retains the RD03 Carbs, air box and CDIs and does not have an oil cooler. It runs fine and I have done many happy miles on it, using it for long distance charity rides.. and off-road. The RD04 engine has a real grunt and a different character to the smoother higher revving 650, but just as much fun to ride.
It was on its way to being converted to a 750 Marathon, but is now back to standard and awaiting pick-up as I have sold it :thumbup:
The RD03 will get the Marathon kit..
Rob used the bike as a long distance commuter and clocked up many 10,000s of miles before 'retiring it ' for a newer RD07, that suffered the same fate
So if it’s cheaper to fix the 650, do that ,
but if you have a cheaper early RD04 engine..... it will drop straight in, but you will need the headers and exhaust too.
As I say mine retained the original carbs and air box and has an RD07 Silencer, runs fine, but you will improve the performance with the RD04 Carbs and Air box, but I was happy with the bike:lol: