alternator stator: how to mount it?

laurentdom · May 7, 2013

Hi Folks,

Does the way the stator is mounted matter (the two wires facing the inner primary case or the outer primary cover)?

If it does not matter, I'll mount it with the 2 wires facing the outer primary case because there will be no risk that they are damaged by the belt. Otherwise, I'll have to find a workaround.

Many thanks / merci beaucoup.

Laurent

Bernhard · May 7, 2013

My understanding is that the wires are mounted towards the inner chain case, use at least two plastic tires, or the wire will get chaffed if these break.

L.A.B. · May 7, 2013

laurentdom said:
Does the way the stator is mounted matter (the two wires facing the inner primary case or the outer primary cover)?

If it does not matter, I'll mount it with the 2 wires facing the outer primary case because there will be no risk that they are damaged by the belt. Otherwise, I'll have to find a workaround.

The stator is usually monted so the wires face the primary cover.
See manual section C34.25 (Also Fig.C12)

"Fit the three stator spacers on to the stator mounting studs followed by the stator on which the lead must be outboard at the 5 o-clock position"

batrider · May 7, 2013

I still loosely ty-wrap the stator cable around the center bolt boss. (I once had the wires cut by the chain.)

Also I add RTV goop to where the wires exit the stator to strain relieve them. (The stator wires make a bend coming out of the stator epoxy and get brittle with the oil and heat, so the outer black sheath and even the wire insulation itself can crack right there.)

pete.v · May 7, 2013

I like to choose the path of least resistance, generally 2:00 or 5:00 oclock facing out to the cover. Stressing to wires as it leaves the stator leads to failure.

This is sort of where it want to live so that's where i sort of keep it.

PeterJoe · May 7, 2013

laurentdom said:
Does the way the stator is mounted matter (the two wires facing the inner primary case or the outer primary cover)?

Electrically speaking, it makes no difference which way it is mounted.

kraakevik · May 7, 2013

and . . . by the way--don't worry overmuch about stator/rotor clearance. If you don't thrash the engine .004" is plenty--and with less clearance the alternator will compensate for any shortcomings in the original design in terms of output

Tim Kraakevik
kraakevik@voyager.net

BrianK · May 7, 2013

kraakevik said:
and . . . by the way--don't worry overmuch about stator/rotor clearance. If you don't thrash the engine .004" is plenty--and with less clearance the alternator will compensate for any shortcomings in the original design in terms of output

Tim Kraakevik
kraakevik@voyager.net

Ouch. You may be right...but most things do expand when heated....having said which, if it works, it works.

maylar · May 8, 2013

kraakevik said:
and . . . by the way--don't worry overmuch about stator/rotor clearance. If you don't thrash the engine .004" is plenty--and with less clearance the alternator will compensate for any shortcomings in the original design in terms of output

Tim Kraakevik
kraakevik@voyager.net

Beware. I have personally experienced catastrophic failure due to inadequate rotor clearance. Took out the rotor, stator, primary chain and inner primary case and bent the gearbox mainshaft. An expensive mistake.

Torontonian · May 8, 2013

Be Afraid , be very afraid. Stator-rotor clearace is important ,even all the way around helped rectify my charging issues and once they rub from heat expansion etc. the resultant disaster is mindnumbing.

pete.v · May 8, 2013

Stator clearance is critical. Use three or more pieces of .010 feeler stock and place them in around the rotor/stator at equal intervals. Tighten the nuts evenly then pull out the feelers. Go around and make sue you have this .010" all around. Some stators have a little excess material on the inside. I have taken a light sanding wheel and went around the inside to clean up the surface. Only if need be.

I think some have even taken a skin cut in the rotor.
Don't assume. Double check this clearance.

laurentdom · May 14, 2013

Thanks to you all for your thoughts.

I fully agree with the idea of paying careful attention to the stator-to-rotor gap, because of heat expansion and potential "faux-rond" (ie when the crankshaft end is not perfectly concentric) which may cause problems.

I've mounted it exactly as you suggest, using 3 gauges and checking carefully that there is a 0,20 millimeters (approx 0,010 ") stator to rotor gap evenly spread all around the rotor.

L.

Staytite · May 15, 2013

Hi All,

I am about to reinstall my alternator and have about 4 to 5 thou clearance on one side which I think is a bit tight.
It's been like that for about 20 years....buy maybe my luck will run out.

What is the best way to improve the clearance?

I could file the holes in the stator a bit to move over it a bit as the clearance is greater on one side than the other.
I guess the studs in the inner chaincase or the stator are not perfectly positioned. (It's a Norton!)

Or I could file away a bit of the inside of the stator on the tight side to give a bit more clearance.

Or even a bit of both.

Which is best?

Thanks
Staytite

laurentdom · May 15, 2013

Hi,

I think the most important point is to have an even clearance all around, as long as it is something like 0,08 - 0,10 millimeter (minimum). That is the clearance I had on my previous alternator which worked fine.

If it is not feasible in your case because of your stator holes, I would rather replace the studs by smaller ones (eg : 6 millimeters instead of 1/4") than enlarging the stator holes and I would take this opportunity to check that the new studs are correctly positionned (ie straight and vertical).

L.

toppy · May 15, 2013

I notice from the photo the stator is mounted so that it overhang the magnet. is this correct mine is also like it but I wondered if it was ment to be that way or if the wrong part had been fitted long ago as there were plenty of other wrong parts fitted to the bike

Staytite · May 15, 2013

Hi All,
Mine was the same. I modified the spacers between the front sproket and the rotor and those for the studs of the stator.
Care is need to keep the stator off the chain. But the rotor nut has a few more threads that engage the crankshaft.
It seemed easy with a bit of thought. I wondered why it was designed like it was. Presumably more electricity is
generated by having the magnet (rotor) central in the stator. But I am not an expert.
Cheers
Staytite

toppy · May 15, 2013

I fitted the stator with a number of washer instead of the spacers so the magnets and stator are level. I have not tried it yet as the rebuild has turned into a full on restoration but hopefully in next few months it will be time to learn how to start it. If alternater does not work I have always planned to fit Alto electric start kit so it will be replaced with the one that comes with their starter kit anyway.

pete.v · May 15, 2013

The one in the photo has been adjusted 1/8" by going to Ace Hardware and getting 3 3/8" spacers off the hardware shelf. I brought a vernier along because they can very 5 to 10 thou between them and I need 3 that were equal.
Keeping the stator square and linier to the rotor is important.

That being said, you do not need full penetration to get good dynamics. You will be fine with stock spacers. I adjusted mine because.......well......it seem like a good thing to do but I have no data to support a positive effect. I certainly hasn't hurt anything.

maylar · May 16, 2013

Staytite said:
Hi All,

I am about to reinstall my alternator and have about 4 to 5 thou clearance on one side which I think is a bit tight.
It's been like that for about 20 years....buy maybe my luck will run out.

What is the best way to improve the clearance?

I could file the holes in the stator a bit to move over it a bit as the clearance is greater on one side than the other.
I guess the studs in the inner chaincase or the stator are not perfectly positioned. (It's a Norton!)

Or I could file away a bit of the inside of the stator on the tight side to give a bit more clearance.

Or even a bit of both.

Which is best?

Thanks
Staytite

I drilled the stud holes 1/64" oversize to allow a bit of adjustment on mine.

Staytite · May 16, 2013

Hi maylar

I like the idea of that. It is difficult to file a hole parrallel.
Do you have problems with the vibration shaking it to a different position?

Thanks
Staytite

alternator stator: how to mount it?

laurentdom

Bernhard

L.A.B.

Moderator

batrider

pete.v

PeterJoe

kraakevik

BrianK

maylar

Torontonian

pete.v

laurentdom

Staytite

laurentdom

toppy

Staytite

toppy

pete.v

maylar

Staytite

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