Std dry weight for r1 is 390lbs
Fazer is 458lbs
Expecting to be able to swap forks over without any mods is incredibly optimistic.
Spring rate, then damping.
I forget which model of gsxr 750 it is (iirc it's the k1-3, but don't quote me), but with a 10mm spacer the std spring is ideal for the r1 forks and plenty out there cheap.
Take my advice or leave it, but remember I used to spanner for Jim Moodie and earned a living from translating rider talk to engineering solutions.
on both of his posts
Plus the standard fork springs are progressive and go from 8.1 to 11.8 and they are considered too soft by most owners. With standard R1 7.1 linear springs you would never get the most basic of items "laden sag" anywhere near what would suit you. At 135m the fork stroke on the R1 forks is 5mm less than the OEM Fazer your start point for sag would probably be between 33 and 45mm
Both bikes as far as I know take 5w oil as standard which is considered to light and 10w is a better option. However changing the oil without changing the springs will make matters worse.
One of the biggest issues I found with the 1000 was its tendency to run wide on acceleration out of bends (Understeer). Trying to dial that out was extremly difficult, but once I got it sorted the bike is a joy to ride fast.
I maintained the standard forks and used 10w oil and Wilber progressive springs.
The reason I fitted Wilber progressive springs in the end was simply because I do a lot of 2 up riding and travel on very undulating roads (as Skippernick discovered
).
5LV You would never hear much of Jim nowadays where is he now? Great rider, one of the few who made on road and track. I will never forget how lucky he was when he got caught up in the aftermath of the accident that took David Jefferies out