KDXRIDER.NET

Anyone? I have been scanning all the old threads on gearing and am just wondering who on here has the tallest gearing. I am making my kdx street legal, an easy task here in monTana. I will prob be fifty fifty street dirt. My bike came with a 14/47 combo, which I am planning on keeping, just want to see who has the most ridiculous tall gearing. This is more academic than practical I know, but I am curious

Plug your numbers into here http://www.gearingcommander.com/ and you can see what you could expect.

My bike came with 14/45. Not so good in the woods. If I could ship the sprocket cheap enough I would send it to you.

It seems like a lot of people talk about hitting the 70s on stock or lower gearing, but according to the gearing commander the 68.1. Are people revving past the redline to get to this? Or are they just telling fish tales.

How is the 14/45 on the street?

Fish tails IMO. I have my 200 street legal. I run 14/47 gearing and sustained 55mph driving is not pleasant IMO. 45 mph is about tops for my comfort level both vibration and engine survivability wise. Yeah, you could probably do 70 mph with it but I sure would not!

I agree with SS109. Stock gearing is 14/47, I believe, which is 3.357:1 (the CS sprocket rotates 3.357 times to rotate the rear sprocket once). I prefer lower gearing for the woods, so for a long time I ran 12/47 (3.917:1) as this was the inexpensive way to get what I wanted. When I needed a new drive set, I wanted to get away from the 12 tooth CS sprocket because they would wear out pretty fast, so I purchased a 13/51 sprocket set. this gives me a 3.923:1 ratio, which was pretty close to the 12/47 ratio, but a tiny bit lower. This pretty much killed any dreams of normal street use - even though my KDX is plated and set up with directionals and all other street hardware.
I saw a KDX set up as a SuperMoto on one of my street bike forums, and I had to wonder what kind of gearing he was running.
A stock KDX may be comfortable at around 45-50 MPH, but sustaining anything over that will feel like you are punishing your engine. In its current form, my bike can get down the pavement to get from trail to trail, but I have to roll the throttle on heavily, then pull in the clutch and glide, - over and over again. It is in no way suitable for sustained pavement rides.
For your purposes, I would suggest finding a 15 tooth CS sprocket and seeing how that feels. With any luck, you will be able to cut/adjust your chain to accommodate swapping between the 15 and the stock 14 without even pulling the wheel off. In all honesty, I have never experimented with super tall gearing on the KDX's. Stock was the tallest I have ever ridden, and that is very good for recreational ice riding.

Yeah something that would allow a pleasant 55mph cruise would be great. Swapping cs would be easiest, does the 15 fit?

Rocky Mountain ATV sells a 15t for our machines (Primary Drive brand), so I assume that they fit.

I am running a 15/43 on my KDX240SM. Still wish I had more top end. It will cruise
nice and smooth @ ~45-50mph. Still not enough to hit the freeway for more than
a mile or two. Does nice in the canyons when speeds are 20-50mph, with short
bursts to ~60-65. I'd hate to hold it there for more than a few hundred yards.
I also have a GasGas EC250 SuperMotard. It is a whole'nuther animal. Must be
geared much diff. in the trans. It is running a 14/40 and will cruise all day between
50-55mph. Not even break a sweat. I think part of the problem is when the power
valve starts to open. At that point the bike either wants to take off and haul azzz
or back off and cruise. I don't know if an off road based motor can handle sitting with
the PV open and only partial throttle @ high RPM. Top of my head guess is that it only
takes around 10-15 HP or less to get one of these bikes to a steady speed with 6,000-7,000RPM.
Maybe some fine tuning of the jetting would help. I fattened up the pilot and the main just
to be safe. I don't foul plugs @ 48/160 with an 1173N needle on the 3rd groove.
I am running 40/1 Motul, btw.
Search "KDX240SM" here for a picture if you are curious.
Good luck, Jeff

Correction.....oops. I checked to be sure.. I have a 14 tooth countershaft sprocket on my kdx240sm not a 15. sorry.
I do not think a 15 will fit.....It would hit the plastic swing arm guard and possibly the cases.
Jeff