So I'm not quite sure how many other people out there own one of my bikes 149 other siblings... but I'm hoping someone can illuminate some things for me:
1. I'm reeeally struggling to understand gearing. I know the gears are arranged in a christmas tree and each gear has a "tooth" count. Then I understand that the size of the gear and the number of teeth affects the rev range, speed, and torque... I don't know how to understand the ratios and numbers people refer to.
2. I know that the fireball stella has been "upgeared" for added performance, but I can't seem to find a definitive explanation for what this is! the vintage226 website seems to suggest that the fireball has p200 gearing, where others have said that only the "primary gear" has been replaced... I don't even know what the "primary gear" is? I thought there's a gear for 1st 2nd 3rd and 4th???
3. How does fireballs upgearing affect tuning strategies? I've read people having mixed results with upgearing and kits and exhausts etc.
I guess I'm wondering if the typical mods suggested to stock stella riders apply as accurately to fireballs (jetting, derestricting airflow, reed mods, exhausts).
05 fireball stellas "upgearing"
Moderator: Modern Buddy Staff
-
double-o-soul
- Member
- Posts: 121
- Joined: Fri Aug 03, 2012 5:13 pm
- Location: Philadelphia
-
Robbie
- Member
- Posts: 536
- Joined: Wed Apr 25, 2012 2:46 am
- Location: Desplaines Il.
Can't help much with exception to primary gearing question.
The clutch drum, which turns at engine speed when the clutch is engaged, has a gear as part of the drum.
This is called the primary drive gear.
It, in turn, spins a gear on the primary shaft......this shaft has all four drive gears as well as the primary driven gear, cast and machined as one assembly.
The four driven gears, those on the axle shaft, are engaged to the shaft by the position of the crucifix.
The primary reduction ratio is the number of clutch drum (crankshaft) turns required to turn the primary driven (input) gear one turn.
For example, a 3.25 primary reduction ratio means the clutch drum, turning at crankshaft speed, means the drum will turn 3.25 times to turn the primary shaft one revolution.
This ratio is added to the ratio of each of the four speeds to give the entire ratio spread.........again, using the example of a fourth gear ratio of say 5.0, meaning five turns of the primary drive gears are required to make one turn of the output gears (axle shaft), so, our overall ratio is 5.0 plus 3.25 or 8.25 crankshaft turns for each wheel revolution in fourth gear.
Any change in the primary drive ratio will change all four gears overall ratio.
It's 6:20 A.M. here......Hope I didn't further confuse,
Rob
P.S.
I have tried to oversimplify a bit......the clutch gear actually drives a idler which in turn drives the input gearset........I figured I'd leave it out of my response to avoid further confusion.
The clutch drum, which turns at engine speed when the clutch is engaged, has a gear as part of the drum.
This is called the primary drive gear.
It, in turn, spins a gear on the primary shaft......this shaft has all four drive gears as well as the primary driven gear, cast and machined as one assembly.
The four driven gears, those on the axle shaft, are engaged to the shaft by the position of the crucifix.
The primary reduction ratio is the number of clutch drum (crankshaft) turns required to turn the primary driven (input) gear one turn.
For example, a 3.25 primary reduction ratio means the clutch drum, turning at crankshaft speed, means the drum will turn 3.25 times to turn the primary shaft one revolution.
This ratio is added to the ratio of each of the four speeds to give the entire ratio spread.........again, using the example of a fourth gear ratio of say 5.0, meaning five turns of the primary drive gears are required to make one turn of the output gears (axle shaft), so, our overall ratio is 5.0 plus 3.25 or 8.25 crankshaft turns for each wheel revolution in fourth gear.
Any change in the primary drive ratio will change all four gears overall ratio.
It's 6:20 A.M. here......Hope I didn't further confuse,
Rob
P.S.
I have tried to oversimplify a bit......the clutch gear actually drives a idler which in turn drives the input gearset........I figured I'd leave it out of my response to avoid further confusion.
-
double-o-soul
- Member
- Posts: 121
- Joined: Fri Aug 03, 2012 5:13 pm
- Location: Philadelphia
damn thanks man!
while googling some of the terms and names of things you mentioned I stumbled on this!
http://www.scooterhelp.com/tuning/vespa.gearing.html
awesome explanation
while googling some of the terms and names of things you mentioned I stumbled on this!
http://www.scooterhelp.com/tuning/vespa.gearing.html
awesome explanation