Rebuilt starter drive

[Stan C]

I am getting an ahhh-ooooh-gaahhh noise when starting my 79 CB 750K. It only makes this sound when I start the bike and it begins to run with the starter button pushed for just a second. I have replaced the three bolts on the drive with higher quality bolts and use blue thread locker. I also installed new rollers, pushers and springs in the drive. It still makes the ahh-oooh-gaahhh noise after the work. I am suspecting a worn or dry bushing at the opposite end of the starter drive gear. Once the bike starts to fire up, the load on the starter drops and the shaft is free to "bounce around " inside the bushing which I think causes this noise. I have not been able to find any detailed drawings of the starter motor to see the construction of it. Anyone had any experiences with this, I would like to hear.

 

[ScottishBadger]

Sounds like a dry bearing in the starter motor. It's easy to remove and dismantle, I took mine out and fitted new brushes last year. Strip it, clean it out and check / lube the bearings. Personally, I'd fit new brushes whilst in there.

 

[Stan C]

Sounds like a dry bearing in the starter motor. It's easy to remove and dismantle, I took mine out and fitted new brushes last year. Strip it, clean it out and check / lube the bearings. Personally, I'd fit new brushes whilst in there.

That's what it sounds like to me as well. I have heard this similar noise in some of the places I worked as a millwright mechanic and it usually turned out to be a dry bushing in need of lube. Thanks for your comment.

 

[Stan C]

That's what it sounds like to me as well. I have heard this similar noise in some of the places I worked as a millwright mechanic and it usually turned out to be a dry bushing in need of lube. Thanks for your comment.

So today I pulled the starter and found a lot of black soot inside of the bush side of the starter. To undo the 2 screws that hold the starter together, I found that if you use a set of medium good quality vice grips with good teeth and clamp them down really hard right next to the threads in a position that allows you to turn the screw counter clockwise, it will break the thread loose with a nice crack sound. If you try to undo the screw at the philips head, you will surely strip the drive of the head. I tried to undo it with a proper philps bit, clamp and wrench but I could see it would be very easy to strip the head. Don't do that ! Once you get the bush side of the starter off, you can clean out the dust and install new brushes if you wish. I lubricated both the bushing and shaft with red grease and reassembled the starter. When you put the bush end back on, you must align it with a 2 finger type slot in the motor body so that everything will line up properly, then the 2 long screws that hold the motor together can be installed. The starter can then be reinstalled into the bike.
It was a great feeling not to hear that AHOOOGAAAHHHH sound again at any time any more. It turned out to be exactly what I thought it was . . .a dry bushing in the non load end of the starter. I also installed a roller kit complete with new springs, pushers and rollers, noticing that the new springs were about one quarter inch longer than the old ones but it made no difference whatsoever.