OK, need some help here. Installed a Rivera Primo Brute III belt drive on my 84 FXST. I was told that it would work from Primo. Now the starter bendix doesn't extend far enough to engage the ring gear. Called Primo and they couldn't help. Also called J&P, who I bought it from and they can't come up with anything either. Seems like I need a longer jack shaft if that could be possible. Any thoughts or suggestions?

did you add a spacer before you clutch basket? or not assemble your jackshaft correct. you can always measure both inner primaries and see if there is a difference.

double check your assembly - you may have put something on the wrong side - backwards. maybe a spacer/washer is on the wrong side of something changing the measurement. You may have gotten a wrong part that looks like it fits. Hard to say without the book in front of me or pics of what you see...