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7/3/2019
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Western NY area, NY
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geeZ177
4/13/2022 11:17am
4/13/2022 11:17am
So last year I got back into riding after 20 years off a bike. I bought a new ktm sx 250. I am a slow +30c / mid pack D guy to date. Since buying this bike I have thought the front end feels nervous/ twitchy. Then I got the chance to ride my brother's 22 crf 250 and this confirmed what I felt. His bike is like an arrow and mine feels all over the place. Everything is stock, but I did adjust the front and rear clickers to ktm's comfort settings. I'm sure at around 200lbs I am too heavy for the stock stuff. But new springs and this and that aren't on the table at this time. I just need some basic chassis/suspension tuning help to try and tame the front end down. Thank you for any help!
Also where is your fork height set? You could drop the forks down if you have the room to get more stability. The problem you are going to run into is you can set your forks for your weight but the rear will be way to soft and your bike is going to be unbalanced. Hate to say it but you really will probably need a rear spring at minimum and maybe a revalve to get it right. The shock really has to be dialed in to get the forks feeling good.
Somethings that help me-
Run 14/48 gearing to get the rpm’s down to take some of the load off the chassis. Run the axle back in the swingarm(once you get the right spring) Green pv spring and jetting with a smooth transition to take the “edge” off.
And you definitely need to go up a spring rate or two in the rear
22 GasGas MC250, Slow 55 y/o Vet C- !
The Austrians need the correct rear spring if you want the front to work.
If the rear is too low, the forks don't get the load to work properly regardless of air pressure and clickers adjustments
I'm 215 lb and put a 48 because could not get a 50 right away but got one finally on it's way
Give the front and rear some time to break in too. Forks in particular are tight brand new.
I added a flywheel weight, unplugged the connector under the tank to get the "soft" map, put the Green PV spring and used AJ's specs to jet the Mikuni.
https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/KTM-HUS-125-150-2…
The Shop
Pit Row
200+gear, if you are a taller rider you might need 48nm rear spring since you move a lot of weight back and fwd.
38mm static, if you can't get the bike to corner with that spring and sag, go up a step more.
Example:
Sag is at 35/103 with 8-9mm preload. Have 2" of Travel left on fork, Difficult to turn, jumping out of ruts, harsh in front. First thought: let's make frontend softer.
Reality: you have a bike that oversteers and fork is pushed to low in the stroke. This also affects bottoming since it is harder to drive the fork through its complete stroke when it starting from a harsh point. Solution: Go to 38/105 and go up a spring rate to drop preload in to 6-7mm range maximum.
You need to be at 38-40 for static. On sand it can drop to 42-44 even if myself like it more around 40.
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