Newbie concerns

The 3 1/2 forum
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

Ah! I DO know how to add pictures!
Morini Jen
Posts: 405
Joined: 12 Jun 2022 18:49
Location: Warwickshire U.K.

Re: Newbie concerns

Post by Morini Jen »

Great result...

Well done, John! :)
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

Thanks, hopefully will be useful to someone with a similar problem in the future!
RedVee
Posts: 303
Joined: 11 Apr 2006 18:40
Location: Wiltshire

Re: Newbie concerns

Post by RedVee »

Good to hear you finally tracked it down. All you need now is some dry weather!
Morinis & Motorcycles - Is there anything else?
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

True
BumbleBee
Posts: 248
Joined: 13 Jun 2017 21:10
Location: Reading

Re: Newbie concerns

Post by BumbleBee »

Sometimes for the bolts that hold the stator on, people make them stand off too much and they hit the back of the flywheel and make a squeeking noise.
Usually either because of washers added or screws with thicker heads than standard.
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

Yes, not much of a gap there!
jasonsantacruz
Posts: 8
Joined: 06 Dec 2024 19:24
Location: Santa Cruz, Ca

Re: Newbie concerns

Post by jasonsantacruz »

Talk about timing, I am having a very similar issue. I get the same rubbing when under load, when I pull the clutch it goes away and at high speeds it goes away. I removed the side cover, removed the rotor, cleaned everything up and can see wear from the rotor/stator touching. I put it back together and still have the noise, so more work to do.

What are the torque specs you used, I went with 64 Nm / 47 ft-lb but heard that it might be much higher?

Thanks - J.
BumbleBee
Posts: 248
Joined: 13 Jun 2017 21:10
Location: Reading

Re: Newbie concerns

Post by BumbleBee »

jasonsantacruz wrote: 10 Feb 2026 03:11 cleaned everything up and can see wear from the rotor/stator touching. I put it back together and still have the noise, so more work to do.
Look at the keyway and the key itself, also look at the taper (look on the shaft and in the flywheel). Sometimes there is a burr on the keyway or the key itself. Sometimes a small lump on the taper made of some flattened rubbish that has got in there. Either can cause the rotor to run out of true. Also similar things can happen with the stator mounting recesses at the 3 screws that hold the stator on. If there are burrs or rubbish in there it can be out of true and might get scuffed by the flywheel.
Last edited by BumbleBee on 10 Feb 2026 10:28, edited 1 time in total.
BumbleBee
Posts: 248
Joined: 13 Jun 2017 21:10
Location: Reading

Re: Newbie concerns

Post by BumbleBee »

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Last edited by BumbleBee on 10 Feb 2026 10:31, edited 2 times in total.
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

It sounds like it's happy under light load,but not under load or no load? Could this be the dreaded play in the main bearing allowing the crankshaft to move very slightly back and forth?
It was suggested to me to check my main bearing for rock with the belt off to get a good feel, sounds like something to try.(Luckily my was fine).
I used 50 lbf, which seemed FT,I wasn't happy going any tighter,I don't think it would achieve anything,and the spring washer should stop it loosening.
Good luck
noc668r
Posts: 19
Joined: 18 Jan 2026 11:48
Location: Northampton UK

Re: Newbie concerns

Post by noc668r »

Is the rotor marking all the way round, and the Stator on 1 or 2 poles?This would suggest movement of the crankshaft?
If it's just one place on the rotor (like mine) then it's probably just a rotor issue, damaged,not seated correctly on the taper.If this is the case, you could try taking the key out and lapping the rotor to the crankshaft with valve grinding paste to remove any high spots.
Obviously a good clean afterwards.
jasonsantacruz
Posts: 8
Joined: 06 Dec 2024 19:24
Location: Santa Cruz, Ca

Re: Newbie concerns

Post by jasonsantacruz »

Really appreciate all the input.

I checked the crank end float and there is a small amount of in-and-out movement, but no side-to-side play. I took over a dozen measurements and it’s consistently coming in around 0.10–0.12 mm, which I believe is in spec.

Thanks again for all the help.
morini_tom
Posts: 1109
Joined: 05 May 2006 13:47
Location: Northampton
Location: Northampton

Re: Newbie concerns

Post by morini_tom »

Endfloat on the crank is generally imperceptible but the standard bearing on the primary side on the 350 is a 6306 C3 for which the axial clearance is usually around 0.05-0.15mm so your measurements sound reasonable.

However if the nut on the primary drive end of the crank wasn’t tight or was bottomed out with too narrow spacers (8 and 10 in the parts book) then under load the thrust on the primary drive gear could allow the crank to move axially. Similarly for the clutch if not correctly shimmed.

If investigations around the crank/stator/flywheel don’t come up with any solutions then it might be worth a check on the primary drive side
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