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Author Topic: UCE Electric Starter Drive?  (Read 1337 times)


  • Scooter
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UCE Electric Starter Drive?
« on: June 09, 2009, 04:02:57 pm »
I've searched the forum until smoke came out of the computer (Do computers have sprag clutches?), but can't find the answer to this one:  Exactly what sort of starter drive does the UCE have, exactly?  Does it have a Sprag clutch?  A Bendix drive?

I found this cutaway on the 'net that appears to show the starter drive (Isn't that it behind the cylinder where the distributor used to be?), and a reduction gear system seems to be visible.  But what engages/disengages the starter?

Can anyone explain what we're seeing here?

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  • Grand Gearhead
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Re: UCE Electric Starter Drive?
« Reply #1 on: June 09, 2009, 04:19:30 pm »
It's a sprag clutch.

The issues that RE has had with sprag clutches are not necessarily an indication that sprag clutches aren't useful items. Sprag clutches are used on many other motorcycle starters, and in other automotive applications, and they can do just fine.

RE implemented a sprag clutch on their older models, but failed to recognize certain issues which led to unreliability of that electric starter system.
Over time, they implemented things to help overcome the problems, such as the improvement to the ignition system, and improved hardening of the gears, and recommendations to use the decompressor to get the engine rolliing over well before starting commenced.

With the new UCE, the implementation is inherent in the new design, instead of being "hung onto" an older design, and has been tested for flaws.
The lessons learned about the ignition requirements have been incorporated into the engine control system, and auto-decompressors have been fitted on the cams, so that the engine gets rolliing before starting commences, and this is automatic so you don't have to remember to do it.
From all indications, it seems that the UCE starter system should have much better expectations than their previous attempts. They are apparently so confident about it, that they deleted the kick starter on the C5 model.
After years of taking a vicious beating from starter failures on previous models, I should think that they are well aware of how bad it can be if they don't make it correctly, and that great pains would have been taken to ensure that nothing such as that would happen on the new models.

We shall see how this all shakes out.
But, we cannot just broadly state that sprag clutches are bad. They can be good.
It's all in the overall design and execution of the system, as to whether they will have good reliability and lifetime of parts.
« Last Edit: June 09, 2009, 04:24:17 pm by ace.cafe »


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Re: UCE Electric Starter Drive?
« Reply #2 on: June 09, 2009, 08:03:52 pm »
To add a bit to what Ace said the UCE sprag is mounted right on the motor sprocket and supported by a big roller bearing. 
Aside from that it is the same unit as on the older engines with the things that destroyed the earlier ones removed or beefed up.
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