How do you calculate the gear ratio on a Honda?

GN Racer · Post by **GN Racer** » Thu Jul 10, 2008 8:42 pm

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....

jstone · Post by **jstone** » Fri Jul 11, 2008 12:50 am

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.

Kenny_McCormic · Post by **Kenny_McCormic** » Fri Jul 11, 2008 2:03 am

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.

Dac · Post by **Dac** » Fri Jul 11, 2008 2:41 am

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.

GN Racer · Post by **GN Racer** » Fri Jul 11, 2008 4:10 am

Sorry, I should have been more specific.

Thanks Dac. That's exactly what I meant.

I'm sure someone knows.

Post by **noiseguy** » Fri Jul 11, 2008 10:51 am

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

Kenny_McCormic · Post by **Kenny_McCormic** » Fri Jul 11, 2008 4:23 pm

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.

GN Racer · Post by **GN Racer** » Sat Jul 12, 2008 1:53 am

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.

GN Racer · Post by **GN Racer** » Sat Jul 12, 2008 10:18 pm

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....

Dac · Post by **Dac** » Sat Jul 12, 2008 10:37 pm

d*** dude

what else you got?

tru72 · Post by **tru72** » Sat Jul 12, 2008 10:55 pm

42x17 is about 8.6
lol to be exact. 8.6470588235294117647058823529412
LOL

GN Racer · Post by **GN Racer** » Sun Jul 13, 2008 3:32 am

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.

tru72 · Post by **tru72** » Sun Jul 13, 2008 4:01 am

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..

GN Racer · Post by **GN Racer** » Sun Jul 13, 2008 5:20 am

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?...

tru72 · Post by **tru72** » Sun Jul 13, 2008 6:11 am

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?