MRC Forum- brought to you by www.morini-riders-club.com Member: g7AW3f

So I started my bike after an oil change and not having run it for a few weeks. I was greeted by a squeaking/graunchy noise at low revs coming from the alternator cover. So off with the cover, off with the flywheel and wriggle the stator coils. Oh dear there seems to be some play! So off with the stator and it seems the long rivets that hold the coil laminations to the aluminium stator plate are ever so slightly loose. Must be enough to rattle/rub against the flywheel, although I could see no witness marks. So bodge a rivet stake to place them against and thwack them with a hammer and punch. Now tightened up, re-assembled and quiet again. Any guesses how long this repair will last OR will i be needing a new (to me) stator?

You can replace the rivets with new ones, or with screws - but if you use screws ensure that the heads / nuts don’t protrude enough to rub on the rotor. Also use loctite on the nuts. - this from personal experience.

Thanks for the advice.

p.s. one of the holes for the m6 screws attaching the stator is nearly stripped. Screw currently just nipped up and a dab of locktite for good measure. Apart from rereading Julian's post about stripped spark plug threads, any suggestions?

An M6 helicoil kit is what you need here. (Helicoil is a brand name trademark but these days you can get kits from many firms that work exactly the same. Recoil and Uni-Thread are 2 brands I've used. A single kit won't break the bank and there are 6mm threads all over the Morinis and every other bike that is metric, so it won't be wasted.

Plus 1 for the helicoil.
If you havent come across a stripped rocker cover screw or a rocker stud or generator cover screw etc etc then you will some day. A right angle drill is a great investment too.
Mark

Thanks, have a right angled drill, never used it though.

Update:
So rivets loose again. Some axial play but not touchIng the flywheel (that I can see). I wonder if it is more crash damage?

1) will be investigating new rivets: anybody know what size I need?

2) is a loose stator enough to make the engine run horribly? Mis-fires above 5500 and will not tickover? If not I gave other problems, oh dear!

Interested to hear how you do fix it when it's done. I have a spare stator in a similar condition-haven't needed it yet!
As for the running problems, I think it would likely upset the earthing of the ignition coil to the back plate and crankcase. It might well behave like a coil that is breaking down (open circuit)
The earlier suggestions of screws with the heads trimmed for clearance must be worth investigating?

Steve Brown wrote: ↑17 Nov 2025 12:03 Interested to hear how you do fix it when it's done. I have a spare stator in a similar condition-haven't needed it yet!
As for the running problems, I think it would likely upset the earthing of the ignition coil to the back plate and crankcase. It might well behave like a coil that is breaking down (open circuit)
The earlier suggestions of screws with the heads trimmed for clearance must be worth investigating?

Upset earthing would explain why it has got progressively worse as I ran the engine.....you know you should stop and investigate BUT you want to get home!
May look at screws and nuts? Thanks Steve.

Forget helicoils!

The latest thing on the block is Stainless steel self tapping thread inserts M6/M8. Drill out the old thread to a prescribed size then screw in the insert in the same way you would a tap...rotating reversing etc etc and cleaning out swarf from the hole every few turns by removing the insert

For example in a side case thread repair select a long bolt...insert this through side case. Put 2 nuts on inside and lock the insert to those

Then assemble the case with some of the other screws so the insert can be entered square and start threading finally leaving the insert in place

Arthur thanks for the suggestion, I'll ponder that.

The good news; I have drilled out 2 of the rivets, I have left the third with the solder joint as I did not want to disturb it. The 2 drilled out rivets are replaced with M4 machine screws, nylock nuts on the back (and a bit of Loctite for good measure). The laminations appear to be concentric with the backing plate and all seems secure. The screw hole that seemed stripped has cleaned up with a tap and I made a longer screw to reach through to some good thread.
I think I have my stator 'repaired'

The bad news; the bike still won't start. the odd pop when I kick it but no sign of real life. The stator ignition coil measure 195Ohms. With the plugs out there is only a very weak spark from the rear cylinder and none that I can see at the front. Given that I am running scooter transducers, a second hand black pickup and the stator coil may measure ok but must be 40 years old I am now at the decision time:
Spend money on:-
More original bits?
Go Barry's route and get the SWF ignition? (as far as I can tell the 12v system works fine).

Searching through old posts lead me to one explaing that you can measure the voltage between the green wire and earth. The suggestion is that 50v would be good. Oh dear mine puts out 5v. Guess it is definitely the ignition coil in the stator.

Parker3865 wrote: ↑11 Dec 2025 10:28 Searching through old posts lead me to one explaing that you can measure the voltage between the green wire and earth. The suggestion is that 50v would be good. Oh dear mine puts out 5v. Guess it is definitely the ignition coil in the stator.

Just caught up with this post. t does look like your ignition coil is kaput. It will be worth getting it rewound for sure. The stator you have looks like one of the high output late model versions.
I mentioned earlier that I had a similar challenge with a loose stator. I've just refitted the thing today! The same three rivets on mine had failed, I hopefully have fixed it with 3 roll pins to align things and 3 x 5mm screws. The holes were enlarged as it had been run while the rivets were loose, so I drilled them to 5mm (after the roll pins were in place in the smaller holes) I had to grind the heads of the screws to allow them to sit right. They are clear of the rotor and it is now charging like a good 'un. I have a generic rec/reg fitted and am hoping it can handle the extra charge current. At least I should be able to use my heated grips and gloves now, in theory! Road testing tonight with lights!

Indeed this is the "bodyless" alternator, last model before Kokussan. The output should be about 200W, charging begins at idle. There should be no Problem with lights and heatet grips