KDX Gearing Question

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#1
Years before I got my KDX, I owned a Honda TL 250 thumper with extremely low gearing, which worked really well on tight trails in the woods, and I would like to duplicate that low gearing on the KDX. What size front sprocket would be recommended, and how difficult is the switch over? Would the chain need to be shortened, or is there sufficient adjustment available in the cam to compensate? Thanks for any input.
 

Houndog

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#2
I know a 12 up front works with a stock chain, but it seems to wear faster than the stock 13 tooth.
 
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#3
I'm running a 12 on the front of my 220, stock chain. and you wouldn't want it geared any lower that that, it works awesome on tight trails
 
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#4
Thanks for the advice. That sounds like just what I need. Is it an easy install, or does it require any special tools?
 

Houndog

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#5
It's easy, no special tools required, I change mine depending on the terrain I will be riding that day.
 
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#6
you really don't need a special tool to take the counter shaft sprocket off but it makes it a whole hell of alot easier. Do your-self a favor and order a set of reversible circlip pliers (inner & outter $20.00) then you can change the sprocket in about 10 minutes tops. Once the rear wheel is removed I can do a whole drivetrain with new chain in about 30 minutes. Real easy but remember if you change your gearing it's a good idea to do the whole drivetrain or else you will wear un evenly..
 
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#7
So it seems to me that all I need to do is loosten the rear wheel, then remove the circlip and the sprocket comes right out. Is that all there is to it?

Years ago when I had a Honda TL250, it was so low geared that I could just put it in first gear, let it idle, and slowly walk right beside the bike as it chugged thru some very dense forest. Think I will be able to do the same here by changing to a 12-tooth front, or will I need to also install a larger rear sprocket?
 
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#8
The kdx won't tic-tic along on the bottom like a 4-stroke. You can make it run close enough to that to get most any job done..but it's never going to be 'exactly like' some other completely different (4-stroke) bike.

Try the 12-47 combo first. Changing to a 49+ will likely call for a 110 link chain (108 is oem). ....imo

You don't say if your bike is a 200 or 220. The two act considerably different. The 200 won't have anywhere near the bottom end pull the 220 does...without a number of changes.

Sorry to bang on the same old drum over and over...but a proper jetting setup will be a huge benefit both on the bottom end pull of things, and the upper end scream of things.

Well...220's don't do a whole lot of upper end screaming....but you get the idea.

Have fun!!
 
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#9
Instaurare,

The TL 250 was a trials bike, right? I wish I had one of those "in the stable" for those 1/2 mph dense forest days (on private land, I might add - most public riding areas aren't too fond of us breaking our own trails, from what I understand...)

The KDX won't "chug along" at idle quite like the 4-stroke. So don't expect to be able to make the KDX to be like the TL - but it works well , and is much more versatile. You'll like the 12T sprocket - and you might ask for a Steahly flywheel weight for Christmas. Again, it won't make the engine like a TL (or Yam. TTR) at the very low end, but it is a noticeable improvement - and you've got a bike with snap , and the ability for speed! The more I ride my KDX, the more I like it!

Yeah...what canyncarvr said!
 
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#10
To answer your question, 'So it seems to me that all I need to do is loosten the rear wheel, then remove the circlip and the sprocket comes right out. Is that all there is to it?'

Yes. Well, and remove the chain guard for access to the sprocket (if we need to include all the steps ;) )

Then re-adjust your chain to spec with the new 12T.
 
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Sep 22, 2003
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#11
I thank everyone for the helpful advice given. Once I raised the frame to allow the arms full droop, the chain was easy to remove, without having to open the master link. And that 12 tooth is great---it gives me the equivalent of one full additional gear lower, with the only drawback of removing my tallest gear, which I never used anyway. It was a very fair tradeoff. I notice already the advantages in climbing more slowly, although, as was mentioned, it does not behave in exactly the same chugging way as my old 4 stroke trials bike. And yes, it is a 220, and I really do enjoy the snap of acceleration that is easily the equal of the old Honda XL500 which I owned for a time after the trials bike. The only thing I would like to change, now that the gearing is done, is to somehow get the bike lowered without messing up the suspension. I am going to substitute low density for high density foam in the seat, and I read the search pages on this subject, but it seems that there are drawbacks in the other mods, such as changing the fork setting. I stand at 5' 8.5", and the bike is easy to mount and ride, but what has troubled me is finding myself stalled on a steep incline and being forced to keep balance until I restart on uneven terrain----I feel like the bike is almost getting away from me. Any suggestions? I will probably add an additional sole to my boots to get a little extra height, but I do wish this KDX were a bit lower.
 
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#12
Farmerj, is that Stealhy flywheel weight an easy install? Does it do a really good job of improving the low end performance? I am definitely interested.
 
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#13
The Steahly flywheel weight is a "bolt-on" item that is very easy to install - and easy to remove should you desire to do so. Your second question -

Does it do a really good job of improving low end performance?
- is more difficult to answer. It depends upon what you mean by "a really good job" and what your expectations are. It will help make the bike less likely to stall. Here's some good reading for you -

<http://dirtrider.net/forums3/showthread.php?threadid=29670&highlight=200+vs+220>

You'll find some more information if you do a search for "flywheel weight".

Some guys really like 'em. Some guys don't. I am in the "really like" camp!
 
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#14
Another 'really like' from the steahly camp!

Mine's great! What I like best is the huge improvement in keeping the bike running on downhills. No longer does just a touch of the brake at the wrong time (about the time you get a bit of air over a rock/root) kill the engine. Try one! I have no experience with the 220 (I thought it had more bottom end than you'd know what to do with...), but I certainly like it on my 200.

re: lowering.

Downside? What would that be?

At 5'8"+, you should be fine. Some saddle time will sort that out. Still, if you want a bit of a drop with the additonal benefit of improved shock leverage, a set of devol pull rods should work fine. Note that KX bolts are required with their rods.

If you're 200lbs or so, they might make the rear spring a bit too light.

BTW...if you haven't set the shock spring sag yet, you should do it now. That will tell you if the spring rate is correct for your weight, too. Don't bother doing it if you're buying some pull rods, cuz you'll have to do it over again after you put the new rods on (in the 'longer' position).
 
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#15
As for lowering, go to koubalink.com
I just had to lower my wifes CRF, and the kouba link works VERY well. It will maintain correct suspension action, is fairly cheap (I think $75 for a KDX), and easy to install. I could not be happier with the results of my wifes bike.