Sprocket driven Alternators

[GammaBoy]

Hi guys, quick question - anyone know anyone that runs an alternator driven from the front sprocket like a 80's endurance bike - either by belt or direct drive?
Want to bin the stock GSX1100 charging system to reduce flywheel weight, reduce the likelihood of the crank end falling off, and remove the heat source of the stator in the oil bath (Shunt type reg-recs have been identified as a pushing oil temps 10-20* higher than same bike fitted with a series type).
I don't do much sitting in traffic on the bike, so not hugely concerned about the fact it won't charge when stopped etc, and have a reasonably large battery on board with fuckall load - headlight/indicators/brakelight/ignition, and would be fine with hooking it up to a charger regularly...

[ozzy1100]

Been complateing the same sort of thing

[GammaBoy]

Just been doing some calcs - with my gearing etc a direct drive alternator will be turning ~1045rpm at 40km/h - and the spec sheets of some of the alternators say they'll be kicking out plenty of amps by then - the 100amp delco I looked at was putting out 30 amps at 1100rpm...

[ozzy1100]

what size is the delco ? you would have to think 30 amps would do the job

[GammaBoy]

what size is the delco ? you would have to think 30 amps would do the job
It's conventional sorta size... it's same sorta size as 70's/80's falcons/holdens used...

[ozzy1100]

i was thinking of looking into bike size ones but it is on the end of a very long list of things to do
my head hurts atm trying to work out mech injection flow rates lol

[Redmohawk]

Sounds like a shit load of work to make something that does fuck all really, You could build a mosfet boost buck regulator that only loads the generator on a bike when power is needed (very little heat produced at eather the reg or generator)

An Ali rotor with N32 rare earth magnets would put out the same or more power into the stock windings and be half the weight of the stock steel item (if your worried about load on the crank/and mass)

If you insist you want to go backwards to a external alt , you'll need maybe 400watt thats 14 volts @ 30 amp ruff enough. Early Kwaka 750 (gpx750) run a belt drive 30 amp alt. Or Suzi use and exteral of ruffly the same physical size but gear driven.

[GammaBoy]

Yeah, I've been looking at the little ducati type alloy rotor with external windings (as opposed to the internal windings/bell shaped rotor), but fitting one of them up is just as much of a fuckaround...

[Hillsy]

I remember a Katana in an old Streetbike mag that ran a Diahatsu Charade alternator off the chain. He put a sprocket on the alt and mounted it on top of the swingarm between the wheel and the frame.

As long as you're keeping twin shocks there's a fair bit of room in there.

[GammaBoy]

I remember a Katana in an old Streetbike mag that ran a Diahatsu Charade alternator off the chain. He put a sprocket on the alt and mounted it on top of the swingarm between the wheel and the frame.

As long as you're keeping twin shocks there's a fair bit of room in there.
That sounds fucking awful.

I'm talking fairly clean installs like below:
Yoshimura GS1000R direct drive:
http://i162.photobucket.com/albums/t242/Bish_500/Katana Build/XR69_zpsbf1df6cd.png


Not a real Yosh 1135R (TL1000R swinger instead of the Over swingarm of the real 1135R), but dunno more about the setup - belt driven from behind the sprocket - I assume it's a GSXR alternator:
http://vanishingpointbikes.files.wordpress.com/2012/08/tumblr_m6or09md0k1r5fvlko1_1280.jpeg

[Hillsy]

That sounds fucking awful.




You could barely see it - it pretty much sat on top of the swingarm pivot so it was almost hidden by the frame (I think he had some bracing in there too like the Yoshi Kat you've pictured).

Anyway, it's an option.

[GammaBoy]

Fair enough. I've got bracing there that would stop you from fitting an alternator in the area above the pivot.