85 ATC 200S - New Sprockets...what size??

[rodgerkrau]

Hello. New to the forums.. looks like alot of great info on here. so I just got an 85 Hondat ATC 200s...its has 18x11-8 tires with stock gearing 11T front/43T rear... front tire is stock size.. 22x11-8.. what gearing do ya'll suggest... I would rather more grunt and pickup than overall speed... however, I dont want to lose ALL top end speed. is there a happy medium? a few people advised me to go with 12T front and 40 rear. help????

[yaegerb]

Hello. New to the forums.. looks like alot of great info on here. so I just got an 85 Hondat ATC 200s...its has 18x11-8 tires with stock gearing 11T front/43T rear... front tire is stock size.. 22x11-8.. what gearing do ya'll suggest... I would rather more grunt and pickup than overall speed... however, I dont want to lose ALL top end speed. is there a happy medium? a few people advised me to go with 12T front and 40 rear. help????

I would change either the front or the rear but not both.

Higher tooth rear = more torque
Lower tooth front = more torque
Lower tooth rear = more top speed
Higher tooth front = more top speed

It's also important to mention that changing the front sprocket vs. the rear is more aggressive. I prefer changing the rear as it's a more subtle change.

For example (and let's hold tire size constant)
Stock gearing: 3.90 (btw, this is a pretty damn low ratio)
12 front and 40 rear: 3.33
So that recommendation is wrong if you want more grunt

So let's say you go with the following
10 front and 43 rear: 4.3
Or a more subtle approach by doing an 11 front with a 44 rear: 4.0

It's really up to you how much torque you want. IMO you have pretty good torque already with a 3.9 ratio.

[rodgerkrau]

I would change either the front or the rear but not both.

Higher tooth rear = more torque
Lower tooth front = more torque
Lower tooth rear = more top speed
Higher tooth front = more top speed

It's also important to mention that changing the front sprocket vs. the rear is more aggressive. I prefer changing the rear as it's a more subtle change.

For example (and let's hold tire size constant)
Stock gearing: 3.90 (btw, this is a pretty damn low ratio)
12 front and 40 rear: 3.33
So that recommendation is wrong if you want more grunt

So let's say you go with the following
10 front and 43 rear: 4.3
Or a more subtle approach by doing an 11 front with a 44 rear: 4.0

It's really up to you how much torque you want. IMO you have pretty good torque already with a 3.9 ratio.

Ahh. Makes sense. So 12/40 would actually be increasing my top speed vs grunt?? I was concerned because stock is 22" rear tires with 11T/43T. If i wanted to compensate the offset of going from 22" tires to 18". What sprockets sizes should i consider?

[yaegerb]

Ahh. Makes sense. So 12/40 would actually be increasing my top speed vs grunt?? I was concerned because stock is 22" rear tires with 11T/43T. If i wanted to compensate the offset of going from 22" tires to 18". What sprockets sizes should i consider?

12/40, as I highlighted, is actually more top speed which is 3.33
11/43 (stock gearing) is more grunt, which is 3.90

Higher the ratio (see ratios above), the lower the gear and they more "grunt" you get.

If you put smaller diameter tires on the bike (go from 22 to 18) then you will actually lose some more top end.

as I already suggested, your current ratio is pretty low. Your current tire size is making up for that lost top end by having a larger diameter. I would keep it the way it is.

If you want more grunt then increase your rear sprocket by 1 or 2 teeth.

[barnett468]

It's quite simple . If you want quicker acceleration with your current tires, the cheapest, easiest, and fastest thing to do is install a 10 tooth counter shaft sprocket . This will numerically increase your gear ratio by around 10% which means it will reduce your top speed by around 10%, so if it goes 50 mph now, it will go around 45 mph with with a 10 tooth front . Also, in the worst case, you will only need to remove 1 link from the chain which you can easily reinstall if you go back to the 11 front . If you change the rear, you need to buy a new chain or buy a section to add to the existing chain.


PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[barnett468]

so I just got an 85 Hondat ATC 200s...its has 18x11-8 tires with stock gearing 11T front/43T rear...

I was concerned because stock is 22" rear tires with 11T/43T. If i wanted to compensate the offset of going from 22" tires to 18". What sprockets sizes should i consider?

I Googled all this for you because I really have absolutely no idea how to calculate any of this so I sure hope it's right.

The circumference (distance around the outside) of a 22" tall tire is 69.11".

The circumference of an 18" tall tire is 56.54".

The 18" tire is 13.47" smaller in circumference than the 22" tire which equates to an 18.18% change which means that the top speed was reduced by around 18.18% when the 22's were replaced with the 18's, so to compensate for the change the smaller tires made you need to change the gear ratio to one of the numerically lower ones posted below, however, this will also reduce the acceleration rate which sounds like just the opposite of what you want to do.


GEAR RATIO REQUIRED = 3.2

GEAR RATIO OPTIONS STARTING WITH THE EASIEST AND CHEAPEST FIRST

13/43 = 3.307
13/42 = 3.203
13/41 = 3.153
12/39 = 3.250
12/38 = 3.166
5/16 . = 3.200 exactly .



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PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[350for350]

So is there a reason that you're wanting to run the 18" tires instead of the 22" ones. I like to use the stock size tires to keep the ground clearance.

[rodgerkrau]

I ride all flat terrain so clearance isnt a concern at the moment. Thank you everyone. Really great info!