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How do you calculate the gear ratio on a Honda?
Posted: Thu Jul 10, 2008 8:42 pm
by GN Racer
Since there are different combinations of countershaft small & large, final, and driveshaft gears, how is the gear ratio calculated?
I had a friend show me how to do this about 15 years or so ago, but I don't remember anymore....
Posted: Fri Jul 11, 2008 12:50 am
by jstone
I THINK you turn the the clutch, and see how many times it takes to turn it before the back wheel makes one complete turn.
Posted: Fri Jul 11, 2008 2:03 am
by Kenny_McCormic
jstone wrote:I THINK you turn the the clutch, and see how many times it takes to turn it before the back wheel makes one complete turn.
That makes sense.
Posted: Fri Jul 11, 2008 2:41 am
by Dac
yeah, that works great, but i believe he is asking about how to know before you put them in. in witch case, i dont know.
Posted: Fri Jul 11, 2008 4:10 am
by GN Racer
Sorry, I should have been more specific.
Thanks Dac. That's exactly what I meant.
I'm sure someone knows.
Posted: Fri Jul 11, 2008 10:51 am
by noiseguy
You guys know how to count teeth and do fractions, right?
10 tooth gear -> 50 tooth gear = 5:1 ratio
10 tooth gear -> 30 tooth gear = 3:1 ratio
5:1 -> 3:1 = 15:1 ratio
Posted: Fri Jul 11, 2008 4:23 pm
by Kenny_McCormic
noiseguy wrote:You guys know how to count teeth and do fractions, right?
10 tooth gear -> 50 tooth gear = 5:1 ratio
10 tooth gear -> 30 tooth gear = 3:1 ratio
5:1 -> 3:1 = 15:1 ratio
I dont pay much attention in math, some engineer i am.
Posted: Sat Jul 12, 2008 1:53 am
by GN Racer
Thanks noiseguy! I knew that it was something simple like that...
I'll do some checking on this tomorrow....
BTW, I replied to your PM.
Posted: Sat Jul 12, 2008 10:18 pm
by GN Racer
Apparently, I'm running 6.475:1 gears in my Spree, and NOT the 7:1 like I thought.
(42/12) * (37/20) = 6.475
Thanks for the help!
My old 8.44:1 gears. Soon to be installed in a new project.
Dug up some parts in the garage recently....
Posted: Sat Jul 12, 2008 10:37 pm
by Dac
d*** dude
what else you got?
Posted: Sat Jul 12, 2008 10:55 pm
by tru72
42x17 is about 8.6
lol to be exact. 8.6470588235294117647058823529412
LOL
Posted: Sun Jul 13, 2008 3:32 am
by GN Racer
Dac wrote:d*** dude
what else you got?
Unfortunately, not a whole lot. Not anymore..
A few pulleys, ramps, clutches, manifolds, drive faces, etc. A long time ago, I used to help others in tuning and installing parts on their bikes. A lot of the time, people just left or gave me the old stuff. I tossed/gave away most of it. The remaining parts I have were in a rollaway tool box, that I kind of forgot about.
Hey Tru72!
Am I not calculating correctly?
(42 Large counter/12 driveshaft)*(41 final/17 small counter) =
3.5 * 2.41176471
=8.4411765 ~8.44 to 1 gears
I'll have to edit my posts again if not. LOL.
Posted: Sun Jul 13, 2008 4:01 am
by tru72
well you know you might have bought that and people usually round it off to the nearest number. best way to check is like jstone said. i put them into a spare block and put the cover on and check them that way to make sure..
Posted: Sun Jul 13, 2008 5:20 am
by GN Racer
No spare S blocks right now, but I'm working on it.
I do have a complete Sym engine that I just picked up.
I'll verify the (gear ratio) numbers by doing the clutch/tire turn method when I get a chance. Maybe I could attach a degree wheel to be somewhat accurate?...
Posted: Sun Jul 13, 2008 6:11 am
by tru72
sym wil be a diffrent ratio...
sorry.. but if you use the malossi set,it wil be diffrent becuase of the smaller gear..
DD wil be 8.44
S wil be 6.75
want to sell some of those malossi?