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2008 KLR650
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Discussion Starter · #1 ·
So looks like I need to change my chain and sprockets and I've looked at the gear ratio pages and such and I'm a simple man so I'll ask here..... What are the advantages/disadvantages of changing the number of teeth from the regular stock sprockets? I'll mention that I am a big dude, 6'4" and 300+lbs, so would I gain anything by changing the tooth count in the front or rear sprocket?
 

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2002 KLR650
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138 Posts
Use the search function and you’ll find hours worth of reading! Tom even put together a great spreadsheet that will show you front sprocket details (indicated/actual speed, rpm) changes.

That said, I’ve put a couple thousand miles on mine in the last month and a half with the stock 15 front, 43 rear and I am changing the front to a 16. Will drop the rpms at (indicated 65mph) actual 60mph about 400 rpm.

All depends on your riding. If I am off-road, I am on fire trails for camping. Mostly 60mph roads and occasionally 70. So I want a little more “length“ out of my gears and am not concerned with losing any first gear off-road capabilities, torque throughout the gears or shift points.

If you’re off-road trail riding you’ll lose some umph in first (and the rest) as it will be a bit taller with the 16 tooth. Perhaps others can comment on weight and going to 16, you may want to keep the 15 for now and see how it fits your riding. It’s not bad at all and the KLR can handle it. Keep an eye on your oil levels! Especially at +4500rpm riding.
 

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2014.5 KLR650
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188 Posts
And if you scroll to the bottom of the page you will find a bunch of threads on the topic ...
 

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So looks like I need to change my chain and sprockets and I've looked at the gear ratio pages and such and I'm a simple man so I'll ask here..... What are the advantages/disadvantages of changing the number of teeth from the regular stock sprockets? I'll mention that I am a big dude, 6'4" and 300+lbs, so would I gain anything by changing the tooth count in the front or rear sprocket?
Blueeyedogre, DETAILS await you from references in posts above!

For a, "Cliff Notes" (summarized) response to your post, I would say: From your weight, you would profit in going from 15-tooth (stock) to 14-tooth (aftermarket) front sprocket. This change will multiply torque to your rear wheel by a 15/14 ratio. With your weight, additional torque might be welcomed (not putting your heft down; I've been on the wrong side of the height-weight chart myself).

Surely, other teeth ratios exist (from the material provided); my suggestion provides only a simple, inexpensive, immediate thrust improving (in my opinion) your KLR650's rideability (maybe rideability is not a word, but . . . I think its meaning clear enough!)..
 

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2018 KLR650
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68 Posts
Use the search function and you’ll find hours worth of reading! Tom even put together a great spreadsheet that will show you front sprocket details (indicated/actual speed, rpm) changes.

That said, I’ve put a couple thousand miles on mine in the last month and a half with the stock 15 front, 43 rear and I am changing the front to a 16. Will drop the rpms at (indicated 65mph) actual 60mph about 4-500 rpm.

All depends on your riding. If I am off-road, I am on fire trails for camping. Mostly 60mph roads and occasionally 70. So I want a little more “length“ out of my gears and am not concerned with losing any first gear off-road capabilities, torque throughout the gears or shift points.

If you’re off-road trail riding you’ll lose some umph in first (and the rest) as it will be a bit taller with the 16 tooth. Perhaps others can comment on weight and going to 16, you may want to keep the 15 for now and see how it fits your riding. It’s not bad at all and the KLR can handle it. Keep an eye on your oil levels! Especially at +4500rpm riding.
 

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2018 KLR650
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68 Posts
I just changed mine to a 16 with stock rear.
On the freeway I think 70 mph was at 5000 rpm.

Dont know how it is on tight technical trails.
 

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I just changed mine to a 16 with stock rear.
On the freeway I think 70 mph was at 5000 rpm.
At any given speed, your rpm is now 15/16 of the rpm with the previous sprockets.

And . . . you have 15/16 of the stock drivetrain's torque multiplication at any rpm.
 

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It has to do with how you ride. I originally thought I would be riding more off-road, I kept the stock 15/43. Once I realized I ride 90% on road, I experimented with 15/42, then 16/43, and finally settle on 16/42. 16/42 dropped my rpm 800 - 900 on the top end. This was great for interstate as I had a lot of reserve if I needed to pass. Went off-road in FL sand once, I could really tell this wasn't optimum for that type of riding but I made it through without too much problem. No matter what combination I use, I get 55 - 62 mpg on rural highways (55 - 60 mph) so I didn't see a big change in the economy. Biggest change was lower rpms in the top gears cruising. This helps because with my 09, any extended time over 5000 rpm it starts to burn oil, always has. If I keep it under 5000 rpm I barely have to add oil between changes every 5000 miles. I'm 6'3" and geared up in the winter carry 250 lbs. Summer gear is around 235 lbs. I can run 70 mph at about 4300 rpm with the 16/42 setup. Currently running 15/42 because I couldn't find a 16 in stock. Running Shinko 705 tires. BTW, there is about a 300/400 rpm difference between a new tire and a tire on the wear bars with the 705s.
 
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