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Bike alternator speed(RPM)
scutter - 29/1/07 at 03:39 PM

Greetings folks, Myself and Robocog saw a Wildmoor snake fitted with a motorcycle alternator, at last i've found one, but I've a few questions.

First, as it hasn't arrived yet, does anyone know how hard it would be to replace the drive gear with a pulley?

Second, what RPM is the alt going to need to turn to generate enough output?

If it's not possible to convert no worries as it was only a fiver, but i doubt it weighs more than a kilo.

ATB Dan.


tks - 29/1/07 at 03:47 PM

I would look at these things:

- how are the bearings? are they lubricated? the type of bearing should tell you some the rpm it can handle..

- how much amps does the bike in question consume? i mean to say is it usefull in a car?

- where did that sprocket engage, being a alternator i can only think of directly to the crankshaft.

it needs some serious rpms 10.000

also isnīt it needed to have regulator fitted? or is it alternator alternator if you get what i mean..

Tks

BenB - 29/1/07 at 03:48 PM

Most alternators are relatively easy to take apart- infact for the ST1100 there's a modification for the pre-96 alternator (28A) which involves grafting on half of a post-96 (40A) alternator.... obviously you might need to machine up an adaptor from the alternator shaft to the pulley wheel....

Not sure re the RPM... Most alternators spin up to about 14Krpm... Don't imagine bike alternators would be very different- I'd aim for about 15krpm... Certainly on the ST the alternator drive is pretty big compared to the alternator drive- I'd estimate a 2:1 ratio, taking it to about 16k... Somewhere in that ball park figure should keep the juice flowing without knackering the bearings....

02GF74 - 29/1/07 at 03:50 PM

quote:
Originally posted by scutter
does anyone know how hard it would be to replace the drive gear with a pulley?

Second, what RPM is the alt going to need to turn to generate enough output?


depends on how the gear is held in place and what sort of shaft; if a plain shaft, a pulley can be made and bolted on (I have contact details of man who can make a ali pulley).

Car alternators run at 2x engine speed; bikes ones, soince bike engies rev to higher numbers, would guess is 1:1. Bear in mind bikes have (or used to have) one headlamp/brake lamp instead of two so if you plan to do a lot of night driving, you may find the ouput is too low.

Any idea of Amps on it?

smart51 - 29/1/07 at 04:11 PM

The R1 generator is bolted onto the end of the crank. The red line is 11750 RPM.

stevec - 29/1/07 at 04:16 PM

Shaft diameter may be a little small and the bearing may not be up to the bigger side loadings that a fanbelt may put on it.
Steve,