Same issue on my `89, the 1989 model was the first year for the modern starter configuration, but the starter was less than 1KW power, it would often bog when the engine came up on compression.

I changed to an all ***** starter with more power about a year ago and it cranks fine.

 

They were indeed very low.. Only .8 kw.. most all newer starters are 1.2 kw and I believe the all ***** is 1.4 kw.. Unless you want to get there super 2.0 starter...

 

A little late on this but... Make sure that the pinion sits about 0.1 to 1/8 inch from the ring gear. I'd also check to make sure that the bushing in the outer primary cover does not have a groove or ridge worn in it... Make sure that the center bolt for the pinion drive is not torqued too tight.

 

Too eliminate the compression issue you thought it might be, put the bike it first gear with the clutch out, roll it backwards so you roll the engine backwards onto a compression stroke. put the bike back in neutral and hit the starter. that way at least you have a bit of stroke before the starter experiences engine compression.
But my money is on starter drive not engaging the ring gear because that's the only whine sound i know, is the sound of the starter motor freewheeling.

 

sprag clutch

my fxr acted just like that. in fact, I bought a new battery for it, because of the hesitation on starting. I'd assumed the Florida heat was getting to my battery. I rebuilt my engine with 10:1 pistons last year and figured that was making it worse. Hot starts, I got a grinding sound every second or third start. I decided to replace the starter clutch to fix the grinding, before it left me somewhere. First of all, it was a very easy job. Second, I was amazed by the difference starting the bike. Even cold starts it just fires right up like I replaced the battery. Hot starts are no issue at all anymore.It's like I have a brand new battery.

 

Mine started that and turned out the starter clutch broke and would catch only once in a while, so it would just spin and whine without engaging the engine. after replacing the cheap part, all was good.