Ok being that this is my first bike and such, if i put on a 13 tooth front sprocket will i loose some top end speed? Im not sure how this will effect that, i do more on road than off road. I keep trying to imagine the gears on a mountain bike, but its not working out right.. so a little help guys. How does your bike react after putting that on compared to stock?

 

i think a better question would be...


What is the stock rpm at 60 mph in 6th?
What is the 13 tooth equiped bike in 6th at 60 mph?

I think my stock bike was about 7000 rpm at 60 mph
I haven't really looked at my tach going 60 with the new sprocket. I do mostly 90% off road with mine. "Trailer Queen"

 

On my stocker 60 mph as indicated on the speedo is running 6000 rpm. I believe I read that our speedo reads 5mph high so running a true 60 is around 6500 rpm. I forget who but in a post down below someone is running the 13 tooth and running 60 mph indicated is at or a bit over 7000 rpm.

 

see i dont wanna loose any top end. quite a few times i go around 65 so id like to probably leave that alone then...

 

From everything I've read you actually will pick up a few mph on top end as the bike really doesn't have the HP to pull the stock gearing. Obviously it will be revving higher but it will also be faster, doesn't sound right I know but its been covered in the gigantic KLX thread on advrider.

 

Give that man the money from the secret envelope please!

The KLX250S stock from the factory will not pull maximum speed in 6th gear! You can actually ride faster in 5th gear than you can in 5th gear on a stock bike. There is not enough power to pull the bike through the air resistance - which increases expotentially as the speed increases.

Just the other day, I had mine at 90 mph indicated!

Yeehaw - interesting ride - don't think I'll be doing that again any time soon! [sm=badidea.gif] (yes it was a long, straight stretch and it took awhile to get there - once there, just don't move or twitch! [sm=gears.gif]

Put a 13 tooth on the bike and see for yourself! It's a completely different bike!

 

Put the 13 tooth on, It makes the bike perform better on the low and top end!! [sm=smiley20.gif]

 

ok i guess that will be next! thanks guys. o btw i was up in the woods tonite, just after it poured, was a little too muddy for the stock tire with 1100 miles on it... needless to say i laid it down... smacked the back of my head off the ground pretty hard, made me see stars and game me thumper of a headache.... but it was fun... thanks for your help guys.

 

With stock gearing, 6th gear is an "overdrive" gear. For anyone that doesn't know, by definiteion a overdrive gear is one that you cannot reach top speed, and is not used for performance and acceleration but only for a lower crusing gear for comfort and fuel economy. On my BMW 6th gear is an overdrive. However on the 600cc sportbike I had, 6th gear was not overdrive, it was required to reach top speed. Some newer cars with 7 or even 8 speed automatic transmission my have 2 overdrive gears.

So yes, you won't lose top speed but lowering the final drive gearing. the biek has a fairly wide ratio gear box, which is one of it's best attributes.

 

If I could make any changes on the bike, it would be some tranny tweaking. I personally would like a taller sixth gear. I often find myself trying to shift to 7th. You know that feeling you get when you are walking down the stairs and you are nearing the bottom and you know you are on the last step, but you really aren't? And you take that last step thinking that's the end but there is one more step there? Yeah - that's what trying to shift to 7th feels like.

The other thing I would tweak would be lowering first gear a little. Basically, I'd like to lower first, raise sixth, and then spread the other gears out a little to even them out.

When I had the 49 tooth rear sprocket on w/the 14 tooth front, I thought the lower gearing was perfect. But that was basically like losing 6th gear at the top end and only having 5 gears - at least in 6th with the 49 tooth sprocket, I noticed about the same RPMs to reach 50 MPH as it was with the stock gearing in 5th. So for me, the perfect gearing on this bike would be as I mentioned above.

I wonder if it is possible to change and how much it would cost to get new gears machined? This is just the kind of thing that I would consider doing, since it would make a huge difference to me. Unfortunately, changing out the final drive gearing can affect the low end, or the high end, but not both. To get both, you gotta do some tranny surgery.