Hmmm, interesting, and I WOULD tell Jim if I were you because
something does not sound right. I do not think your brushes should be
getting that hot. You may find out that you still have a problem after
you change the drive setup. This may actually be a motor setup thing.
Did Jim advance the timing for you? Are you sure that the rotation is
the right direction? I only have a 4 brush motor and have run mine
with a 400 amp Alltrax without ever having those type of issues.
Anyway, it sounds like you are already heading a different direction,
but I would still be a little worried that something is not right with
your motor setup. I would expect to be able to drop your motor onto my
bike with my front sprocket and run it all over without any heating
issues. Your motor sounds a little bigger and beefier than mine, and
mine has proven to be well up to the task.
damon
------------------------------------------------------------------------
> Date: Sun, 2 Nov 2008 21:20:45 -0500
> From: [EMAIL PROTECTED]
> To: listserv@electricmotorcycles.net
> Subject: Re: [ElectricMotorcycles] BMW update
>
> Like starting to smoke hot (don't tell Jim!). Right from the brushes -
> actually one set I think. Could be they aren't set yet as the motor had
> just been rebuilt. All the brush holders were fairly hot to the touch.
> The motor housing was cool. I should have run the brushes in with no
load.
>
> I didn't measure amps - left my Palm with the Alltrax software at work,
> but I bet I was pulling over 300 motor amps.
>
> I know riding around slow in the yard on grass (the bike) is probably
> worse case, but I really would like a bit more low end. My problem is I
> have to climb a gravel driveway when I get home, so I need decent low
> speed power at a lower SOC on the battery.
>
> I know you run a lower ratio too Damon, though I think my rear tire is
> bigger - 19". I calculated I get 2.33 MPH/100 RPM. That gives me 63MPH
> at 2700 RPM, so I really can afford a higher gear ratio, as I really
> don't need to go over 50 or 55. The bike seems to roll easily. I did
> some pull tests with a spring scale on a flat concrete floor and it
> pulled easily (I forget the value...).
>
> In any case, I already tore it down and started planning out how to run
> a chain reduction to the drive shaft. Actually I think it'll be a
better
> setup physically. Just have a bit of chain noise. BTW is there a source
> for drive belts? I would think that would be quieter. Since it's before
> the final 3.36:1 ratio it doesn't have to as beefy as a final drive
belt
> would be - more like a primary belt (if anyone uses them there). I
don't
> know much about chain and belt drives having owned shaft drives for so
> long now.
>
> Anyway, I was grinning a bit!
>
> - SteveS
>
> damon henry wrote:
> > I would not give up on the shaft drive just yet. What do you
define as
> > hot? It's likely that the insulation in your motor is rated up to 180
> > deg Celsius. Try measuring the brushes with a temperature probe after
> > you heat things up. How many amps were you pushing through the motor?
> > More amps will give you better acceleration (and make things heat up
> > even quicker). And finally, what speeds will you be doing most of
your
> > riding at, what kind of RPMs will your motor usually be turning, and
> > how often will you be riding up hill? Lugging the motor at low speed
> > around home will heat things up because there is no air flow being
> > generated by the internal fan in the motor. Pulling the same amps to
> > maintain a higher speed, the motor will run cooler because of the
> > higher RPMs.
> >
> > I have been running my motorcycle for years with a chain and a 14
> > tooth (now 13) front sprocket and a 41 tooth rear. That overall ratio
> > sounds to me like it is close to what your shaft drive setup
> > provides... unless I am reading your ratio backwards.
> >
> > Having said all that, I can ride my motorcycle around all day long at
> > low speed without any heating issues at all. The times that my motor
> > has been the hottest has been in the snow when I have used it to drag
> > the kids around the cul-de-sac on a sled at very lows speeds. That's
> > easily remedied by a well placed armful of snow, but the extra
drag of
> > towing the kids really heats things up. How well does your motorcycle
> > roll?
> >
> > damon
> >
> >
> >
> >
> >
------------------------------------------------------------------------
> >
> > > Date: Sun, 2 Nov 2008 08:26:43 -0500
> > > From: [EMAIL PROTECTED]
> > > To: listserv@electricmotorcycles.net
> > > Subject: [ElectricMotorcycles] BMW update
> > >
> > > Another milestone (of sorts) in my BMW motorcycle conversion
journey. I
> > > had played around with an Elec-Trak motor direct to the shaft drive,
> > > which proved woefully inadequate. From taking with several people it
> > > seemed that I really needed to go to a higher gear ratio (the
> > 'built-in'
> > > ratio is 3.3:1); or, possibly, a bigger motor. Jim Husted found
a nice
> > > 7", 8-brush, motor for me. I thought I'd try it direct just to see,
> > > which I did yesterday. It did pull away (slowly) from a stop and
> > > actually had ok acceleration, but the brushes got hot from my
low speed
> > > driving around the yard.
> > >
> > > So I guess I'm finally convinced I need to add a gear reduction.
I had
> > > hoped to use a planetary gearset, but really couldn't find anything
> > > appropriate, so it looks like chain and sprockets. Now I have my
winter
> > > project.
> > >
> > > Too bad, as the direct drive was absolutely quite; really sweet.
> > >
> > > - SteveS
> > >
> >
> >
> >
------------------------------------------------------------------------
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> >
> >
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> > Version: 8.0.175 / Virus Database: 270.8.5/1762 - Release Date:
11/2/2008 9:51 AM
> >
> >
>
>
>
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