I have twin 525 with xr drives with sport master lowers. When i put the port side in reverse, not all the time but some times there can be up to a 2 or 3 second delay.
Any one have any idea why? There are about 170 hours on the drives. Thanks

Make sure cable is adjusted properly, my first instinct is clutch cone but your issue is reverse (minimal use) so leads me to think it is a adjustment issue, have the drives been off possibly switched from side to side? or has that drive ever been shifted into reverse at a high RPM that you know of?

Most likely a cone clutch. Have you just serviced it or switched to synthetic gear lube?

Yep, I agree most likely the cone clutch is worn.

Make sure your linkage is centered when the drive is in neutral. Pull the cotter pin and remove the barrel nut.. wiggle the cable and see if it goes back into the holder easily (while the drive is in neutral) adjust the barrel so that is slides in easy and replace the cotter pin. If that doesn't change, you might want to remove the back cap and make sure the screws are tight on the shift rod at the linkage and cam. Also note the cam bolts are in place. If all looks good then look at the cone. If the cone ridges look warn (shinny) or metal is removed it could be the cone. If the surface the cone sits into in the gear is damaged, it can be polished. I see very few cone clutches go bad, so it is not my first assumption.
Hope this helps.
Dick

Thanks for all the help. There was a 2 inch spacer i had removed in the begining of the season. It has been acting up in the last few weeks. but not all the time, some times its fine and then other times it just has this delay. Thanks again for your help