Some quick background into why
I'm replacing both the R/R and the Stator.
My 2006 Sprint ST has electrical gremlins of at least one variety. The ignition doesn't always try to turn the starter, and sometimes it fires but is missing the oomph to actually get the bike going, and sometimes it fires up before the ignition button is all the way down on the bars. The behavior is awesomely intermittent. Hot engine, hot weather, cold engine, cold weather... no distinguishable pattern thus far as to when it does whichever. Seemingly this was going on with the PO for a while because I was quick to notice a grinding noise from the starter itself due to being abused by these circumstances.
Late last season I replaced the starter because it was abused enough to need it anyway, though I suspect root cause was and remains the electrical situation.
This year when I went to fire up the bike it was 100% dead despite being on a trickle charger over the offseason. I found that the negative battery terminal was discolored and all the plastics surrounding it was melted... this while sitting still in a garage with the bike off and a reputable trickle charger attached. Still not sure how that happened, but my #1 suspect is some aluminum foil the PO had taped to the underside of the seat... I can only assume to act as a poor man's heat shield against the exhaust. My post-Holiday season ass must have moved the bike in the garage at some point and pressed that foil between the positive/negative terminals. Not sure, but open to other ideas about how something that's off gets shorted out to that degree. I haven't been riding much, and the same trickle charger has been keeping my battery topped up and easily firing the new starter for the little bit I've gotten on the road this year. So the cause doesn't appear to be the charger itself, but I'll grant it's not been trying to charge anything through -20 winter days which might stress things very differently.
Here and now
I think I might still have a short in either the clutch safety switch or the kickstand safety switch as once in a blue moon I'll push the start button and have absolutely nothing happen as if one of those are engaged. That's a different matter though, as keeping the bike up on a trickle charger has allowed easy starts all season provided the starter is allowed to actually engage. So add me to the echo of voices all over the forum that land on "yeah I dunno about the specifics, but these bikes really do love a full battery" I have a voltage meter on the bike so I keep an eye on what's happening with it while running.
The voltage meter I have installed only reads 12v in two cases:
1. The bike has literally just started off the trickle charger's overnight charge.
2. The RPM's are over 6k.
It never reads over 12v, and if I don't keep the RPM's up it walks as far south as 8v... which I barely even believe to be able to keep the bike running and think it's more likely a not so accurate measurement from my $10 meter. In any case, I don't see a circumstance in which either the R/R or the stator is not poop. I found DEcosse's excellent write-up
on how to diagnose and only replace what turns out to be the issue, but I also saw lots of recommendations for Rick's replacement stator and the Shindengen SH847 R/R as worthy upgrades over OEM just for the sake of it. I'm not able to find too many weekends for motorcycle maintenance so I've gone ahead and ordered both, with a plan to follow the guide to diagnose to confirm which it was for my own curiosity, but then go ahead and replace both anyway.
I did some hunting and wasn't able to come up with any Sprint specific issues about replacing either. There's a few hints that relocating the R/R and maybe even needing a fabbed mounting for it might be necessary, but I've not managed to find a specific thread or how-to.
So, as I prepare to pull this bike apart armed with two brand new components as well as crimps, extra electrical wire, spare fuses, and a mile of heat shrink... I'm hoping to be able to replace anything I find that looks damaged and button it all back up in a day. I ask anybody who's performed these swaps on this gen of a Sprint to confirm that they did have to relocate or fab a bracket or something... just so I can be sure to have a plan before I get stumped by it with the bike in pieces.
I'll take some photos as I go and post updates to maybe get a guide made up and added to the Maintenance Tips
for anybody else doing either of these specific swaps on this gen Sprint.
I have a long history of loving 80's bikes that didn't have safety switches so assuming that problem survives what I do here, I'll likely fix those switches by entirely bypassing them and just be sure never to start the bike without the clutch engaged. This is the first bike I've owned that has had those protections... and apparently it's not going to have them for long lol.