KZ440 Starter Suicide?

Does anyone know what the skinny on the starters for the kz400/440s are? I spoke with the guy who runs the Baltimore Cycle salvage (who is really nice, knowledgeable guy), and he mentioned that the starters have a tendency to burn out the insulation between the windings, making them useless.

At the time, I was having difficulty starting the bike, and when I opened the starter I found lots of black gunk around the brushes and commutator. It seemed to be an excessive amount - more than just normal brush-wear. According to the Cycle Salvage dude, this was likely melted insulation.

After a thorough cleaning, the starter worked properly again, but I'm having the same issues yet again. I assume it's the starter, as the other electrical components of the motorcycle test OK. The starter, however, appears relatively clean. Confusing as hell.

Anyone else experience similar problems with their starters? I would hate to lose this war to a poorly manufactured starter.

Not sure, you'll have to go through some diagnostics to find out what it's going on. There is also a starter clutch to deal with and it could produce a symptom that mimics a starter problem. The fact that you cleaned the starter and then out was fine could be just coincidence.

The recurring symptoms are a weakly/not-cranking starter motor when the engine is hot or full choke is applied. I'm assuming this is due to a weakly running starter due to some faulty component within the starter circuit. The starter runs OK if bench tested.

Here's what I've already gone through:

2016 - bike started running poorly, then refused to start
- spark present with plug out, but not sure if it was sparking under compression
- primary and secondary coil within spec resistances
- pick up coil within spec resistance
- IC igniter appears out of whack
- replaced IC igniter, bike works - problem solved for time being

2017 - The starter motor starts cranking weakly when bike is hot or choke is applied. Eventually, the starter motor fails to crank at all.
- starter relay is good
- disassembled starter, found nasty black gunk everywhere
- cleaned
- zero ohms between commutator segments
- O.L between segments and central shaft (?)
- starting system worked well upon installation of cleaned starter motor

2018 - yet again, starter motor cranks weakly/fails when engine is hot or choke is applied
- battery is new, charged
- charging system good - regulator/rectifier test within spec
- alternator output good
- Starter looks ok inside, not sure what to think.

Any suggestions/ideas appreciated. My instinct is that a recurring starting problem has something to do with a poorly operating starter, especially when most of the electrical system has been sifted through already.

Nice job documenting what's what. I'm impressed. Starters certainly can draw too much amperage but when you bench test it It's fine?

You've no doubt checked the ground to the motor from the battery right? Even replaced it just in case? Can't find a starter on eBay?

It's never a bad idea to scour eBay or Craigslist for a future parts supply for bikes you are going to keep awhile

Does the 440 have a kick starter? Prolly not huh?

Wow, not a whole hell of a lot of starters on ebay huh?

I'd guess there may have been an issue

Try Craigslist locally. Might be parts bike time

That's why I'm loathe to get rid of my kick start bikes with points and plugs. Come the big EMP I can go riding

There is a Caltric rebuild kit but that won't touch the windings but it's only 12 bucks

The starter bench tests fine. I tested resistance between the starter body and the battery negative terminal and found no resistance. That's what you meant when you asked if the starter was ground right?

I did see a refurbished starter on ebay for $125, but that's more than I'm willing to sink into this bike at this point. A cheap rebuild kit for the brushes might not be a bad idea.

I wonder what the symptom of poor starting with full choke and/or a hot engine indicate. It makes sense that the engine would require more power to crank with the choke fully applied. I'm not sure how a hot engine would be implicated here.

One thing I actually haven't checked is whether the starter gets battery voltage at the positive terminal when running. That might indicate if a wiring issue is resulting in a weak current to the starter right?