Denso Alternator, how to fit mechanically

[RC 166]

Now some more info about Mr Jung's alternator adapters from back in the mid 2000s. Edit: spelling Jung

One of the local club members showed me his Jung alternator conversion that he collected personally from MrJung in ca. 2005. It is supposed to be one of the very first ones produced with welded-together drive hub from CBX-Kawa hubs and screw/epoxied oil splash shield. He says it has worked flawlessly since first installed. No problems at all. No oil sucked out through the crankcase vent either... I also looked at the welded-together drive hub and it is very precisely done.

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[Warwick Biggs]

Peter, I would love to find a lightweight alternator that I could adapt to my CBX race bike in order to overcome all the problems of total loss. After taking kg's out of my crank for quicker pick up I don't like the idea of adding a heap of weight to slow it down again but it is hard to find an adequate lightweight generator to power 3, even ultra low resistance coils.

[CBX-tras]

Even in the beginning, Stephen Jung realized that there was a necessity for the oil, splash shield.

If the conversion you buy today doesn't have it, expect high oil loss, through the breather that is directly above the alternator.

The shields on mine were welded onto the main plate.
The core alternators were completely disassembled, rebuilt, re-wired, and coated prior to assembly, testing and shipping. The couplers were custom made, one piece, for quality and production.
Photo of what I used to produce, NLA :

[RC 166]

CBX-tras,

Nice product you got there!
Any picture of the welded splash shield?

[RC 166]

Warwick,

Just a wild idea... What about gearing it down, or attaching to something further down in the transmission chain, maybe even to the gearbox countershaft (at the front sprocket)? It will let the crank rev up more freely, not feeling the direct load from the alternator. It will for sure give you less charging efficiency, but will at least counteract "total loss". And of course, any on-board charging system will cost power!

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And... if any administrator reds this, can you please fix so that I receive e-mail notifications on thread reply's? As of now, I don't get any.

[CBX-tras]

CBX-tras,

Nice product you got there!
Any picture of the welded splash shield?

I had them out of 1/4 inch thick, aluminum tubing, welded to the inside of the adapter plate.
This is the only photo that was close enough, from my archives, 10+ years ago.

[RC 166]

Clever approach, alu tubing as raw material.. Nice welds.
And 1/4" must be easier to weld than the 2mm shield I tested.

[daves79x]

Just an observation - a couple of hp loss and a few more pounds of weight due to having an alternator is not the problem with being competitive racing a CBX.

[CBX-tras]

Having an ample/robust electrical supply, from my perspective, far outweighs all the problems associated with the stock alternator.

[Syscrush]

Since this appears to be the place to talk about alternator solutions, am I crazy to think that one day it might be possible to have a modern high-output alternator that fits in place of the OEM unit to retain the original cover? I love the quality and performance of my CBX-tras conversion, but still think that the OEM cover looks way better.

[512tr]

What is wrong with the OEM alternator except for the gear/clutch drive, which could easily be improved?

[CBX-tras]

The other main issue is how the brushes engage the slip rings, like a race track. The outer brush will wear out almost twice as fast as the inner brush.
With the Denso alternators, their compact size has less rotating inertia and the brushes are 90* to the shaft, resulting in very little and even wear over time.
Form follows function.
Besides, the stock alternator (relatively low output) has NO cooling. The excessive heat buildup can cause premature stator and rotor separation of the windings.

[512tr]

CBX-tras, you have some valid points.

When I converted to lithium battery/Rectifier-Regulator I was very skeptical and how this would turn out, especially with the little lithium battery I using....but so far, I’m pleasantly surprised how well it works.

I have the modified clutch drive with friction pad, the charging voltage is constant at 14,4 volts when driving and dropping just below 14 volt at idle.
Power output wise is more than enough to supply the ignition/coils/ lighting (all lighting is LED) and charge the battery even at idle.

So far so good

[CBX-tras]

The problem that the Honda engineers identified, is when the rotating mass (a LOT!) of the stock alternator is directly coupled with the primary shaft, the inertia will "flywheel" the motor, preventing the motor itself from rotating on deceleration.
The smaller and lighter Denso alternator doesn't do that as much while providing more amperage than the stock unit.
So, when you downshift coming into a corner, the motor RPM won't slow down as fast as you'd like and continue to propel you in a forward direction.
The same is true for the wheels. That's why, over time, race bikes have gone to smaller diameter wheels with lower profile tires.

[Rick Pope]

Not to mention that the alternator/flywheel puts additional strain on everything connecting it to the crankshaft, thus the clutch to give that energy an escape path.