2004 KX 250 getting set up for Tight Goat Trail style single track...

[Charlie500]

Ok, what I have done so far... IMS tank, 9 ounce fly wheel weight, FMF gnarly pipe/turbine core silencer, hand guards, Pro Tapers cut half inch off both sides.... Now, Gearing... Stock is 13 49 which is way to tall for some of the crazy 1 track hill climbs I need to get up. I found a 12 tooth front sprocket I tried out and now it will only go like 20 miles per hour on fire roads... Does any body have a 04 250 2t they ride gnarly 1 track with? I'm also thinking about tossing in a v-force reed valve and possible a reed spacer. Do these help out on the 2-fitty's as much as the 5-hundos? My main concern with the bike is the close ratio transmission... I don't know if I will be able to get it set up correctly for what I need it to do...

[KevinTwoStk]

One tooth difference on the countershaft is supposed to be equal to about 3-1/2 teeth on the rear sprocket. So 12/49 would be equivalent to 13/53.

I think 13/50 and/or 13/51 are worth trying. One of those is probably just low enough without being too low. The added benefit to keeping the 13-tooth countershaft is that it's going to be easier on the chain compared to a 12-tooth.

[Charlie500]

One tooth difference on the countershaft is supposed to be equal to about 3-1/2 teeth on the rear sprocket. So 12/49 would be equivalent to 13/53.

I think 13/50 and/or 13/51 are worth trying. One of those is probably just low enough without being too low. The added benefit to keeping the 13-tooth countershaft is that it's going to be easier on the chain compared to a 12-tooth.

That's what I was thinking to try next was 13-51... I'm hoping it wont be too low.

[TJXK]

I have read that a 12 tooth will wear your chain prematurely.  I'd stick with changing the rear if that's true.

I think that suspension work and the right set of tires would be the biggest upgrades.  Maybe even run an 18 rim in the rear which is supposed to be best for single track (I haven't tried it) and would further lower the gearing(wrong).  

Refurbish the brakes if needed.  A kickstand is a nice upgrade as well.

[Charlie500]

I have read that a 12 tooth will wear your chain prematurely.  I'd stick with changing the rear if that's true.

I think that suspension work and the right set of tires would be the biggest upgrades.  Maybe even run an 18 rim in the rear which is supposed to be best for single track (I haven't tried it) and would further lower the gearing. 

Refurbish the brakes if needed.  A kickstand is a nice upgrade as well.

I got the suspension dialed in... There's a really great suspension tuner near my home town that got that set up for me... Brakes are fresh with new fluid... I don't know about switching up to an 18, seems like a waist of money... The only thing I would gain is having a bigger side wall... My main concern is getting the gearing set up. I understand a smaller counter shaft would wear the chain pre maturely, but it is the cheapest way to make a big step in the gearing. Now I know I will try 13 - 51 and if that doesn't work I'll trade the d**n thing in for a 300 xc-w...

[Enginerd]

I run 13-52 on my 05 KX250 with a Steahly 11oz. flywheel weight.
It transformed the power characteristics of the engine.
It is a joy in technical singletrack now.

[KevinTwoStk]

I used a cheap chain/sprocket set to find my gearing, then replaced it with better stuff when the first set wore out.

[TJXK]

I don't know about switching up to an 18, seems like a waist of money... The only thing I would gain is having a bigger side wall...

The rim is harder to damage, you can run a beefier single track tire, less flats, lower gearing(nope),  plusher ride and better traction.  That extra little bit of sidewall on a dirt bike tire is huge, relatively speaking.  You also get more off road tire options, even trials tires.  Those are all pretty important for what you're doing.  It's the same idea as off roading a truck.  You wouldn't put 22 inch rims on a jeep and go wheeling with no sidewall.  

Rims are expensive though.  

[Ims Roll]

I used a cheap chain/sprocket set to find my gearing, then replaced it with better stuff when the first set wore out.

cheap chains are nice, only takes one

I don't know about switching up to an 18, seems like a waist of money... The only thing I would gain is having a bigger side wall...

The rim is harder to damage, you can run a beefier single track tire, less flats, lower gearing,  plusher ride and better traction.  That extra little bit of sidewall on a dirt bike tire is huge, relatively speaking.  You also get more off road tire options, even trials tires.  Those are all pretty important for what you're doing.  It's the same idea as off roading a truck.  You wouldn't put 22 inch rims on a jeep and go wheeling with no sidewall. 

Rims are expensive though. 

how does a 18 vs 19 lower your gearing? a 18 inch rims fits the same tire height as a 19, you can get a 110/100/19 and a 110/100/18 ect ect.

[KevinTwoStk]

It was still a Tsubaki chain. I said "cheap" not "junk."

No frills, no nickel plating, no O-rings. I regularly measured it to make sure it wasn't getting past the wear limit, and I replaced it well in advance of that limit.

Then again, maybe I got away with it because it went on a 125...

Point taken, though. Parts need to be at least over a minimum quality threshold or they shouldn't go on the bike in the first place. And yes, quite often "cheap" ends up being expensive when said part fails and causes collateral damage. Again, point taken.

[Foxx4Beaver]

Unless you're on a Ramen Noodle budget, and can't afford to buy a chain every couple years...don't be too worried about running a 12T counter.
I've been running 12-47 on my 00 250 all this year with absolutely no problems...I'm a retired "A" motocrosser, with an overly twitchy clutch hand.
I use the same chain as I run on my 500...RK MXU-RING..they're very narrow(reason I went this route was to help save my 500's sub-frame)...and they're 3lbs lighter than an average o-ring....and they have an average of 9000lbs tensile strength...(reason they last)

http://www.ebay.com/itm/RK-CHAIN-GB520MXU-120-UW-RING-RK-CHAIN-120-LINKS-MX-OFFRAOD-CHAIN-HEAVY-DUTY-/141100783742?hash=item20da43187e&vxp=mtr

...I bought one of these chains for my 500 a few years ago when I got it...and I've never had to adjust/touch it yet. Same thing with my 250 running 12-47....I went all this year, and never had to touch it. A $100 every couple years for a decent chain is peanuts...
Hell...I spend $100 a MONTH just in tires.

[TJXK]

how does a 18 vs 19 lower your gearing? a 18 inch rims fits the same tire height as a 19, you can get a 110/100/19 and a 110/100/18 ect ect.

You're right, it doesn't.  Blaming the wine!   

The rest of the points stand though...

[Charlie500]

Unless you're on a Ramen Noodle budget, and can't afford to buy a chain every couple years...don't be too worried about running a 12T counter.
I've been running 12-47 on my 00 250 all this year with absolutely no problems...I'm a retired "A" motocrosser, with an overly twitchy clutch hand.
I use the same chain as I run on my 500...RK MXU-RING..they're very narrow(reason I went this route was to help save my 500's sub-frame)...and they're 3lbs lighter than an average o-ring....and they have an average of 9000lbs tensile strength...(reason they last)

http://www.ebay.com/itm/RK-CHAIN-GB520MXU-120-UW-RING-RK-CHAIN-120-LINKS-MX-OFFRAOD-CHAIN-HEAVY-DUTY-/141100783742?hash=item20da43187e&vxp=mtr

...I bought one of these chains for my 500 a few years ago when I got it...and I've never had to adjust/touch it yet. Same thing with my 250 running 12-47....I went all this year, and never had to touch it. A $100 every couple years for a decent chain is peanuts...
Hell...I spend $100 a MONTH just in tires.

Hey man I hear ya... I'm not complaining about spending money on the bike... Trust me I know how expensive riding is, I've been riding all my life... I built Shlepy's 500 he can vouch for me. I'm just trying to get this thing where I need it to be. If it will never be there then whats the point of dumping more money into something that i'm not going to be happy with and just sell off any way? If I can get happy with gearing then I will have no problem investing in some new wheels... I will probably go with a60's/talon hubs.... but no sense in buying wheels for a bike that will never have good trail gears right?

[The Flyin Hawaiian]

Both my wife and I raced enduros on 04 KX250s. We ran 13-51 gearing and more recently my wife switched to 13-52. The 13-52 works very well. I went with 13-53 on my 07 KX250 since they are lacking in the lowend dept. The 04 will stomp the 07 into the ground when it comes to lowend and broad power.

[TJXK]

I hear ya.  I think any bike can be modded to your taste, but the cost combined with some informed trial and error can get old.

I'm still trying to get a better trail setup for my 03 KX250, but money is the limiting factor.  ...and sadly my 05 CRF450R is loads easier to ride in the tight stuff (Tillamook State forest) with just a 51 sprocket.  

My list includes a gnarly pipe, 04 spring mod, and fixing the squishy suspension.  Feels like I'm riding a spring board.