Starter...4 brush or 2 brush?

[Lodogg2221]

Just wondering if one is better than the other...

This is in regard to Mike81GS850's bike, which previously had very rich running issues...a new petcock (thanks to the board for that fix) fixed that, and its running great now.

Doesnt start very well. I ordered a starter rebuild kit, and the one I got was the 4 brush Mitsuba, and the starter in the bike is a 2 brush Mitsuba. So, we cleaned it up good and put it back together, same result, VERY weak, will not turn the engine easily, sometimes not at all. Battery is good. Solenoid is good. A direct jump from the battery (full charge, good condition) gets the same result as using the factory wiring. I even tried it with the headlight fuse out, thinking that maybe the headlight bypass during start relay mod might help, but there was no change. Wiring is good, we went thru it all recently...

Do you guys think a rebuild will do it, or should he get a whole new starter? And if new, is the 4 brush a better starter?

Thanks!

[posplayr]

Rebuild

From what I'm reading you have:

a.) good connections between the starter and the battery ( there is a large red wire that bolts direct to the starter and a black that bolts to the engine ground)

b.) Good battery (is it new or are you using a car battery?)

c.) good solenoid (did you measure the resistance? I was able to disassemble and file the internal contacts)

d.) You cleaned it up real good (did you re grease the bearings?)

e.) The motor still turns slow. hmmmm...

Well unless the brushes are fried, it sounds like the windings may be bad. There is not much you can do unless you know how to rewind armature and Field windings.

If it sounds sounds anemic using a car battery and booster cables it is likely winding issues .

Posplayr

[rustybronco]

Question, is the 4 brush plate compatible with a 2 brush starter.

did the mica on the commutator need to be under cut and if it needed to be under cut, did you?

[Lodogg2221]

A: Connections good
B: New Battery with good charge
C: Have not measured, but bypassed it with same result
D: Cleaned and greased
E: Yes, still slow, but did not try it on a car batt.


did the mica on the commutator need to be under cut and if it needed to be under cut, did you?

Huh?

[rustybronco]

A: Connections good
B: New Battery with good charge
C: Have not measured, but bypassed it with same result
D: Cleaned and greased
E: Yes, still slow, but did not try it on a car batt.


did the mica on the commutator need to be under cut and if it needed to be under cut, did you?

Huh?

Mica is used as a insulator between the copper bars on the armature. it needs to be lower than the copper bars so the brushes will maintain proper contact with the commutator.

http://books.google.com/books?id=kfIC04vdXYcC&pg=PA265&lpg=PA265&dq=undercutting+the+mica+on+an+armature&source=web&ots=4NuszYHJeU&sig=_-hgBKLPsTN9uqatssra_6zzXDM&hl=en&sa=X&oi=book_result&resnum=5&ct=result#PPA264,M1

[Lodogg2221]

No, it was good. Well, it looked ok anyway.

[argonsagas]

Mica is used as a insulator between the copper bars on the armature. it needs to be lower than the copper bars so the brushes will maintain proper contact with the commutator.

http://books.google.com/books?id=kfI...sult#PPA264,M1

A good point, but not necessarily a definitive reason for failure.

What can happen is that the bars wear unevenly and then the mica can remain a bit above, as a protrusion, which keeps the brushes from making the best contact, or only intermittent contact.


In case of badly burned bars I have filed all of it down until bars and mica were the same height, but now smooth and even and then the starter turned nicely.

(Unfortunately, it kept on turning because the starter clutch chose that time to lock up and my brand new brushes were worn away in one day. )

It sounds like the windings are not in the best condition, and if so the starter can be rewound, but it would likely be easier to just get another starter.

[Lodogg2221]

Thanks for the info. Id have thought it could be rebuilt, but once we figured we had the wrong kit, and cleaned it up really good and there was no change, well, I was afraid it was going to need a new one...

Any point to getting another used one and rebuilding it? Is there a way to tell if the winding is bad? Other than the obvious visual inspection...

[lecroy]

I have never even seen a 4 bush motor except for the pictures posted on this site. Seems like it would be a better setup just having more surface contact but I'm not sure.



I am just finishing two. I start by cheaning all the parts. Resurface the stator contacts and then clean loose material between them with a small model knife. I then change out all the seals, shims, brush plate and the plastic feed thru. Lube all the bearings and put it back together with a drop of blue. Then I do a break-in where I power the motors with no load. I use a power supply rather than a battery. On for 3 minutes, off for 10. I repeat this 5 times. Then call it good. I am cycling them while I am writting this. Trying 9 volts this time to try and keep the arcing to a minimum while the brushes wear to the contacts.


Friend gave me these after my original one had a major melt down. One has the same part number as the one from my 83. It is marked 31100-49500; 028000-9600 and was made by Nippondenso. The other motor was not marked but has all the same outside dimensions. The stator and magnets is a 1/2 to 3/4" longer. It has no rubber seals like the 83 does for all the screws. The end plate where the positive terminal runs through is much thicker. It uses the same brushes and bearings as the other motor. I believe it was also made by Nippondenso. The attached picture shows both motors, the 83 is in the back.

Can anyone tell me what this unknown motor came from? I would like to try and locate another one.