Hi all,
Well, Mike asked for a report on how the gear changed worked on my bike, so
here goes.
Went Wednesday to the Milan Dragway Test/Tune session. I'd only been to one
other wednesday nite race, and it was pretty packed. This nite was the
same, and the last one for the year. Even the 40 degree nitetime temps
didn't scare anybody off. Guess those gassers make big power in the cold,
but I was definately down on power. I can always squeak 600 amps out of
each string of Hawkers, but this time I could only pull about 500.
Launches were OK. I geared 1st gear just a tad taller than my last time to
the track where I was getting quite a bit of wheel spin. The track was
definately cold, but was also sticky. 2nd run I made I thought I pulled the
front end up, at least stroked the shocks out, but maybe didn't lift the
wheel. One guy commented on how the bike launched really good, but just
quit a few hundred feet out. I can't even feel the clutch pull in. Not at
all. Looking at the data confirmed what that guy said. You can see the
volts drop and amps spike when the clutch comes in. But the amps take
forever to drop back off. The volt take forever to come back up. I was
clearing the 1/4 mile at about 2000 RPM. I can run about 2900 RPM in 1st
gear.
Analysis? That larger split between 1st and 2nd gear is bogging the motors
down. But mathmatically, I don't know why I went with such a steep 2nd
gear. At 2900 RPM I'd be turning probably 90 MPH. Not going to happen.
So then I did some homework. I read that a shunt motor (mostly the same as
a PM motor) doesn't respond well to changes in load. I guess I've proven
that. A shunt motor won't make the torque to reaccelerate the load. A
series motor is the answer for that, or at least a compound motor.
So I'm looking at a few options:
A) Change the gearing so 1st gear is 1.375:1 and 2nd gear is 1:1. This will
put a smaller load change on the motors, and should hit just over 70 at 2900
RPM.
B) Lower the voltage way down on the clutch (voltage yet to be determined)
so that the clutch actually slips and bring on the added load slowly. Might
tear up the clutch though?
C) Toss the transmission and see if I can get it running as quick as I did
before the transmission.
Oh yea, Suncoast can ignore the preceeding as this is all in an attempt to
dominate at the upcoming Battery Beach Burnout.
Later,
Darin
BadFishRacing
----- Original Message -----
From: "Mike" <[EMAIL PROTECTED]>
To: "ElectricMotorcycles" <[email protected]>
Sent: Friday, September 22, 2006 10:44 AM
Subject: Re: [ElectricMotorcycles] Harley Drags
>About the only thing I haven't tried is changing the gearing between 1st
>and 2nd gear. What are you guys with 2 speeds running for gear ratios?
>Or if you're running 2nd and 4th gear? I don't think I've got enough
>leap from 1st to 2nd, as I can't seem to SUCK AMPS when I grap 2nd gear.
>Any thoughts?
Darrin, Did you find any answers since you posted the above? I'm always
curious.
Mike
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