I'm looking for chain and sprockets for a klx 140 and am having a hard time finding a place that lists them online for that bike. I do not want to buy stock- is aftermarket available yet? Thanks. Also-this is a bike for a younger kid, are most people keeping stock sprocket size?

Ive not been having much luck finding anything for this
bike yet.

As far as sprocket size goes, I have left my 12 year old
sons bike stock so far. I am actually going to gear down
a bit though. Proabably over the winter. No hurry right now.

I would like to find a 12t front for the wife's bike. I wonder if the 110 front sprockets cross over?

I thought that I read that the wheels on the kx80 are  the same as the 140, so is that how people are finding aftermarket rear sprockets --just order one for a kx80 and it should fit a 140? Thanks-if anyone knows

kx 85 has 420 sprockets but if you buy the conversion 428's made by jt and renthal, and a few other companys, they bolt on allthough not sure on the fronts, have a 1 tooth bigger rear on hers now

What is a conversion 428 sprocket?

I beleive the KLX 140 comes with a 14 T front and 50 T rear.  The 140 L comes with a 13 T front, and possibly a 51 T rear?  I'm going to try putting the 140L 13 T in the front of my wifes 140 to see if it helps.  I beleive there are a few aftermarket rear sprockets available

Yup, I just got a set for one of my customers.  You need the 428 conversion sprocket from JT for a KX 100.  The 428 "conversion" lets you run the larger 428 chain on the kx80/100(stock is 420 chain on these bikes)  The KLX140 uses the larger 428 chain like the XR 100.

Just because I am lazy, does anyone know how many links in the stock chain?
I am thinking of +2 on the rear and a nice new Gold chain for my sons bike.
Any reccomendation on suppliers?

Expat said:

DID chain is what I use.

Last weekend I put the 13T 140L sprocket on my wifes KLX 140.  The smaller front sprocket helped, but not nearly as much as I thought it would.  Her last bike was a 2001 XR 100.  I'm not sure if it had stock sized sprockets or not.  I never really looked as it was her first bike, and we had little experience at the time.  I will assume it was stock as everything else on the bike was stock.  Seems even with the 13T in the front and stock 50T in the back of her 140, it has no where near the low end power of the '01 XR.  When she'd stall out on a nasty hill climb on the XR, I could jump right on it in the middle of the climb, and it would tractor me right up anything.  I'm about 6'4", 200 lbs so I was impressed with the XR climbing power.  Even with the 13T in the front, when we went out to the hills yesterday, if I ever stopped the bike on any decent climb, it still didn't have the power to even get the back wheel spinning again with me on it.  I'm thinking of putting a 54T rear sprocket on (this would be a KX80 428 conversion sprocket) and seeing if that fixes the problem.  Does anyone else have any input on this issue?  Is there something I don't know about that makes the XR a better trail / climbing bike than the KLX 140?

Do the sprocket.  The XR100 is a great engine in a crappy chassis.  I'm doing a conversion right now for my wife.  2003 CR85 that I'm putting her XR100 engine in.  We are doing a 120cc big bore, cam shaft and a valve job.  I think it's the way to go.  I'm not very impressed with these newer super heavy bikes like the 140 and the CRF150f and 230f.

I'm not nearly as impressed as I thought I would be either.  I wish we'd of hung onto her XR 100 to use as a trail bike,  and used this klx 140 for out in the open desert when she needs more speed for the sand.

dwilliams1 said:

Yeah for the $800 or $1000 you got for the XR it's totally worth hanging onto it instead.  Maybe buy another one!

The 54T Rear sprocket is on back order, as soon as I get it I'll post the what kind of difference it actually seems to make.