Replacing the Nippon Denso Alternator
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Old and New Alternators

Here's a picture of the old (left) and the new (right) alternators side-by-side on the workbench. Notice the puny cotter pin that was holding the castle nut in place on the old unit, and compare it to the cotter pin on the new unit. I had heard that the stock cotter pin was woefully undersized - and here's the proof!

Fortunately, my new alternator had a more substantial cotter pin in place, so I didn't have to replace it.
Old vs. New
Step 7: Separate Alternator from "Cushion Drive"

As per Rich Maund's excellent write-up, installation of the alternator and the setting of the proper amount of gear lash is made easier by installing the "cushion drive" first. So, I separated the two units by removing the 4 nuts (and lock washers) that held them together.

Once complete, it looks like this:
Separate them!
Step 8: Clean Up Gear Teeth

May as well go ahead and remove the rough edges of the new alternator drive gear with a small file. It's just that much less "swarf" to fish out of your oil sump at the next oil change...

Sorry for the poor focus on this picture - but hey, they can't all be gems!
Clean the teeth!
Step 9: Install the New "Cushion Drive" and Alternator

Ok, this is a bit of an "underwhelming" conclusion - I didn't take any pictures because there isn't a lot of new territory to be covered.

As per Rich Maund's excellent write-up, I installed the "cushion drive", but didn't tighten up the nuts initially. By turning the back side of the drive unit (looks like a "Y"), you can hear a slight "click". Rotating the entire drive unit clockwise on my bike removed the play, and thus removed the "click" - rotating it counter-clockwise increased the play leading up to the "click". I found the point of rotation of the entire drive unit that seemed to be about 1/2 way between no play and maximum play.

Then, using the kickstarter (gearbox in neutral or this won't work properly), I rotated the engine just a little bit and re-checked the play. If it tightened up any, I turned the "cushion drive" counter-clockwise to get the play back. If using the kickstarter increased the play, I did nothing. Then lather, rinse, repeat until you've made a least one full rotation of the engine. Then, tighten up the two nuts holding the "cusion drive" against the engine.

Finally, re-attach the alternator to the "cusion drive" and wire it back up. Install all the bits removed earlier, and you'll be ready to test the installation.
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All content copyright 2006. This page was last updated on July 4, 2006.