30 year old Z750 won't start all the time

Hi peeps, new member here; looking for some help/advice/info if possible. Hope you can stick with this while I describe symptoms.

I've got a 30 year old Z750 and I'm having a few starting issues with it. The bike was in storage for 2 years and got it out and MOT'd etc. about 5 weeks ago. Not quite a clean straight away start when I picked it up but it ran allright and I rode around a bit, few stops and starts en route to visit peeps; showed a little reluctance once more throughout the day but after parking up after a fair run that evening I left it for about 10 mins and when I came out it wouldn't start again - at all. Left it, started first thing next morning so rode back to garage, went over it, mechanic thought starter clutch maybe on way out as new battery (tested ok) etc. Did same thing and wouldn't start for him either after I'd switched off after arrival. Left it for about an hour, started again.
Brought bike back here and because it seemed reluctant to start I did that 350 mile journey straight with only fuel stops - started each time on refuelling. Returned home, next day, did same thing, went uh uhuuuuh uhuuuuh, nearly started then wouldn't. After that no chance. AA picked it up took it to garage here. They tried it, replaced starter solenoid, seemed ok, tried to start it again later, nothing, so they started on the wiring - replaced section of wiring loom as a little brittle from storage - started again. I picked it up next day, started fine again from cold; got it home, later did same thing again, dodgy start. Checked with garage, they hadn't checked starter clutch at all even though I said I thought that might be issue - assumed once solenoid and wiring allowed start that that was the problem. Called garage, said bring it back - tried to start, went uh huh uuuhh huuuhh and then slower again then nothing. Next morning and morning after that starts bloody fine again from cold. So, garage trip delayed BUT after a run it did it again and I had to get a bump (at least with solenoid replaced it WILL bump now), ran well again once started. Next morning start again and then as soon as I tried to start it after refuelling same again!!

So, it doesn't seem to want to start from hot - any ideas before I take it back to the garage? Could the starter clutch being on the way out have burned out the solenoid the first time it wouldn't start at all without even the uh huuuh and just been a false flag for mechanics to the real problem? Is it likely to be the starter clutch if it does actually start sometimes? Bike runs perfectly well once started. Shouldn't be wiring surely after getting so much of the old crappy stuff replaced - was done at Armstrongs on the Hill (Westgate Rd) Newcastle by the way, s'posed to be allright there.

Any ideas or anybody else had this problem? Thanks for your patience in reading and any replies.
Cheers
Liz

First, let me welcome you to KZR. May I ask the year and model of your KZ750?
On to the technical stuff:
I would check out the charging system first. If it is charging O.K. I would probably pull the starter and take a look at the brushes. It could need refreshing.

Should say that wasn't me picking it up for the first time - I've had the bike 5 years, so not been a numpty and bought a duffer

You talk funny. Good thing I have the Urban Dictionary at hand.
I strongly suspect we can get you sorted and back on the road.

Hi Koolaid, thanks for the welcome She's an '83 L3, no major mods, only a 4 into 1 and K&N's - tries to be a streetfighter bnut only got halfway there and is now looking a bit decrepit after 2 years in storage.

First time around double checked the new battery and that was spot on on test, even disconnected and hooked up to a bigger new battery, still wouldn't start. Between not starting and starting it doesn't seem to lose any charge; does seem to be charging allright. Did consider the brushes being worn too - could be it.
Was possibly heading back to Armstrongs this afternoon with it if it will start and didn't want to have a one sided conversation about what's up with it - I originally said starter clutch to them but they obviously didn't check that thinking they'd solved the problem with solenoid and wiring. They obviously didn't try and start it more than once after doing that or they'd have noticed the problem.

Hahah - just spotted the 'talk funny' post - wait till I start mixing my Scottish vernacular with all the Geordie stuff I've picked up since moving here to NE England!
But I see you're in Indianapolis so probably most of what I say will be incomprehensible to you lol

Geordie. Good thing I left the dictionary open.
I really like the looks of the L3, nice styling. Striped tank, dual shocks. Reminds me of my KZ750E on steroids.
Pull your starter. You'll want to pull the carb bank for easier access. It is very easy to get to after that, two bolts for the cover and two bolts holding the starter to the engine case. There will be two bolts holding the cap with the brushes onto the rest of the starter that contains the armature. I would disconnect the battery first, even though the cable to the starter has the solenoid between it and the battery.
I just rebuilt the starter on my GPz last year, so it is all fresh in my mind. Let us know what you find.

And I am actually from Texas, just transplanted.

Thanks for that - will let you know what happens.

Yes, the original does have a striped tank but mine (as per pic) has a Z650 tank, tailpiece and seat (still requires further adjustment lol) and is black and silver now; due for some respray work after languishing in storage but think the plan now is, once I can guarantee every time start, to run her over the season and do the cosmetic work, including a new exhaust, over the winter.

With hindsight it would appear that I have also inadvertently landed on a US Zed site while looking for a Kawasaki owners site - whoops. Probably means I won't be whizzing round for a cup of coffee once I'm up and running lol - still, some interesting threads and useful info on here so, despite distance, will remain. Thanks for the help

This is the Internet. We have members all over the globe, all connected. On another site I belong to we had a couple visit from down under. They got a bike and we all went on a rally. Loads of fun, rode a bunch, swapped stories, all was good.

It is the starter motor - on its last legs - so locating a replacement now.

They can be rebuilt, you know. Why don't you post some pics so we can better understand why you believe it needs to be replaced.

Hi Koolaid - the starter motor is out of the bike at the garage (what you probably call the Shop) and we've been having difficulty finding a replacement. These guys seem very genuine and it's their belief, and mine from the age of the bike and the starting problems I was having, that the starter motor is too shot for a repair kit.
I'm looking for either a very good second hand one to keep the price down or a reasonably priced new one.

If anyone knows where I can get a starter motor for my 1983 Z750 L3 (in the UK if at all possible) I'd appreciate a reply. I've tried quite a few breakers now with no luck, either getting the wrong model or they're in no better condition than my old one.

Many thanks
Liz