22 ktm sx 250 suspension help

geeZ177
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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!
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soggy
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4/13/2022 11:56am Edited Date/Time 4/13/2022 11:59am
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105 is a good starting point. I have a FC 48nm(I think) spring I would sell ya cheap if interested. I’ll have to check what it is when I get home.

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.
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suspensionguy
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4/13/2022 12:28pm
Soggy is right. You need a rear spring. The stock 42kg shock spring is WAAYYY to light for a 200lbs rider. You need a 50 but a 48 is a step in the right direction. I weight the same and race 250sx off-road and would consider it stable. Without the right rear spring you’ll be chasing your tail.

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.
opyguy
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4/13/2022 3:45pm
What air pressure are you running in the forks? If you’re running below 150 psi it’ll sit low and tend to wander
And you definitely need to go up a spring rate or two in the rear
mxstate
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4/13/2022 6:25pm
Soggy is right. You need a rear spring. The stock 42kg shock spring is WAAYYY to light for a 200lbs rider. You need a 50 but...
Soggy is right. You need a rear spring. The stock 42kg shock spring is WAAYYY to light for a 200lbs rider. You need a 50 but a 48 is a step in the right direction. I weight the same and race 250sx off-road and would consider it stable. Without the right rear spring you’ll be chasing your tail.

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.
+1
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

geeZ177
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4/13/2022 7:15pm
Guess I will have to pony up the coin for a spring. I run the fork about 151. She is broke in, has lik 12-13 hrs on it now.
AJ565
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4/13/2022 8:21pm
151 sounds a bit low to me. I’m 175 and ran them at 155. Granted I’m Vet A speed so that’s gonna play into it as well, but landing off jumps is still gonna have about the same response. For sure get a rear spring. The forks will feel like garbage because they are trying to hold the rear of the bike up. With the new spring set your sag between 103-105mm is the sweet spot for these bikes then the forks will work much better. I like them down around the 3rd line to get some more weight on the front end to help with the lack of traction. Another thing is the rear shock likes to pack up in braking bumps and is kinda harsh on rough tracks. Open the rebound up 2-3 clicks and open the high speed up 1/4-1/2 turn and it really makes a big difference on the bike.
geeZ177
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4/14/2022 9:24am
Dumb question but where is a good place to get springs and is there a weight chart or something to go by?
sandman768
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4/14/2022 10:27am Edited Date/Time 4/14/2022 10:35am
geeZ177 wrote:
Dumb question but where is a good place to get springs and is there a weight chart or something to go by?
Factory connection springs are good and they warranty them if they break… call them & they will,advise proper rate for your weight & ability. make sure you are bleeding both fork air screws before every ride…what line are you at on the forks within the clamps? As others have stated, you have to have the proper rear spring & sag in the rear before you can get your fork setup dialed in.
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geeZ177
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4/14/2022 12:17pm
I am at work so I'd have to double check which line. But the forks should are set where it came from the factory.
sandman768
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4/14/2022 12:42pm
geeZ177 wrote:
I am at work so I'd have to double check which line. But the forks should are set where it came from the factory.
It’s just another tuning tool to slide forks up & down the clamps to get desired feel. Usually long, fast, rough track you want stability, so first or second line works good, tighter track with a lot of ruts & tight turns, slide forks up to 3rd line to get quicker steering response.not sure what spring rate comes on your 250 stock, but often the 450 springs are stiffer, you may be able to get a take off stock 450 spring for cheaper than brand new…
AJ565
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4/14/2022 5:18pm
geeZ177 wrote:
I am at work so I'd have to double check which line. But the forks should are set where it came from the factory.
I had a problem with mine that the forks were really harsh the very first time I rode it. Pushing on the suspension felt like it was in a bind. Loosened the triple clamp bolts and the whole front popped because it was twisted from when they put the front wheel on the wrong way. Maybe double check that on yours too.
willbilly
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4/14/2022 7:20pm
geeZ177 wrote:
Dumb question but where is a good place to get springs and is there a weight chart or something to go by?
Slavens Racing has the best spring rate chart. Race Techs is too soft. Diverse springs makes low weight chrome silicone springs for the same price as the big companies.
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geeZ177
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4/15/2022 10:33am
So the biggest question I have is more about the basics vs. Modifying suspension to taylor my weight. Let's say I have my shock and forks set up for my weight and I am still having a nervous front end. Is it nervous because it's too light on the front end and I need to put more preload on the rear shock to help weight the front or am I off base on this?
Falcon
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4/15/2022 3:56pm
Lower the forks in the triple clamps until they are flush, slow down the rebound (forks) by going clockwise on the rebound clickers, and run the steering stem a little tighter. You can also experiment with raising or lowering the front tire pressure. (Sometimes this makes a big difference, but it will depend on your racing surface.)
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geeZ177
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4/15/2022 9:10pm
Falcon wrote:
Lower the forks in the triple clamps until they are flush, slow down the rebound (forks) by going clockwise on the rebound clickers, and run the...
Lower the forks in the triple clamps until they are flush, slow down the rebound (forks) by going clockwise on the rebound clickers, and run the steering stem a little tighter. You can also experiment with raising or lowering the front tire pressure. (Sometimes this makes a big difference, but it will depend on your racing surface.)
Thank you, this was the kind of info I was initially looking for. Lots of videos online telling you what clicker controls what part of the shock or fork. But they don't really explain the why's or the scenarios like I am experiencing.
geeZ177
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4/15/2022 9:19pm
soggy wrote:
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105...
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105 is a good starting point. I have a FC 48nm(I think) spring I would sell ya cheap if interested. I’ll have to check what it is when I get home.

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.
Shoot me a message on what you're looking for on that 48 spring, thanks.
soggy
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4/16/2022 6:17am
soggy wrote:
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105...
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105 is a good starting point. I have a FC 48nm(I think) spring I would sell ya cheap if interested. I’ll have to check what it is when I get home.

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.
geeZ177 wrote:
Shoot me a message on what you're looking for on that 48 spring, thanks.
I just looked. It’s a 4.6kg spring. Not sure if that’s gonna cut it for you. But if you want it $60 and it’s yours.
suspensionguy
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4/26/2022 11:23am
soggy wrote:
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105...
Did you set your sag? You won’t get close to the correct preload on the rear spring at your weight but getting your sag close 105 is a good starting point. I have a FC 48nm(I think) spring I would sell ya cheap if interested. I’ll have to check what it is when I get home.

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.
geeZ177 wrote:
Shoot me a message on what you're looking for on that 48 spring, thanks.
I got a 4.8.. $60
wr74
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5/3/2022 2:27am
A lot of what you’re feeling is simply the difference between a two stroke and four stroke. This is accentuated by comparing a modern Honda four stroke with the Ktm two stroke. Honda’s have a heavier front wheel weight bias, Ktm’s are the complete opposite, they have the least front wheel weight bias. Add in the difference in feel between the air fork and a spring fork and this is what you get. Jumping onto a Ktm 250 two stroke after 20 years away from the sport is a game move. Even many regular Japanese two stroke riders struggle to adjust to the 250 Austrian smokers.
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geeZ177
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5/3/2022 5:51am
wr74 wrote:
A lot of what you’re feeling is simply the difference between a two stroke and four stroke. This is accentuated by comparing a modern Honda four...
A lot of what you’re feeling is simply the difference between a two stroke and four stroke. This is accentuated by comparing a modern Honda four stroke with the Ktm two stroke. Honda’s have a heavier front wheel weight bias, Ktm’s are the complete opposite, they have the least front wheel weight bias. Add in the difference in feel between the air fork and a spring fork and this is what you get. Jumping onto a Ktm 250 two stroke after 20 years away from the sport is a game move. Even many regular Japanese two stroke riders struggle to adjust to the 250 Austrian smokers.
Yeah that is what I was wondering. If besides being a two stroke, if the light front end is just a KTM trait.
geeZ177
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5/24/2022 3:33pm
So I was able to pick up a 4.6 spring from a vital member. Definitely had helped me with the overall ride and seemed to help the front end. But now a new problem, seems like the bike wants to stand up in any rut or corner. Any idea on this one guys? For what it's worth I have gained some speed so I'm sure part of it could be me. Thanks for any help!
AJ565
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5/24/2022 4:42pm
geeZ177 wrote:
So I was able to pick up a 4.6 spring from a vital member. Definitely had helped me with the overall ride and seemed to help...
So I was able to pick up a 4.6 spring from a vital member. Definitely had helped me with the overall ride and seemed to help the front end. But now a new problem, seems like the bike wants to stand up in any rut or corner. Any idea on this one guys? For what it's worth I have gained some speed so I'm sure part of it could be me. Thanks for any help!
What’s the sag set to? These bikes like the 103mm area.
geeZ177
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5/24/2022 6:20pm
I would have to double check but I believe I was in the 102-103 range.
aees
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5/25/2022 12:56pm
Sag, static and race + preload on spring?
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.
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geeZ177
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5/26/2022 5:35pm Edited Date/Time 5/27/2022 2:04am
But it cornered better for me with the softer spring...obviously I was used to that. But I have several hrs of time now with the 46 spring. Just looking for opinions or options. Like i mentioned beforehand I wish there were videos out there explaining if you feel this or that on a bike your should try this or that. Not so much explaining what the components of a suspension are. One thing I did notice the other night at practice was that I now that I am gaining speed I am dragging the rear brake a lot. When I raced as a young man in the 00s I used to be a heavy front braker and would lose the front end as well as a lot of motos. So I feel I may be over compensating for that with more rear brake.
aees
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5/28/2022 5:30am
geeZ177 wrote:
But it cornered better for me with the softer spring...obviously I was used to that. But I have several hrs of time now with the 46...
But it cornered better for me with the softer spring...obviously I was used to that. But I have several hrs of time now with the 46 spring. Just looking for opinions or options. Like i mentioned beforehand I wish there were videos out there explaining if you feel this or that on a bike your should try this or that. Not so much explaining what the components of a suspension are. One thing I did notice the other night at practice was that I now that I am gaining speed I am dragging the rear brake a lot. When I raced as a young man in the 00s I used to be a heavy front braker and would lose the front end as well as a lot of motos. So I feel I may be over compensating for that with more rear brake.
Difficult to give feedback without the above numbers/info. This is due to that if you pass a certain point in setting things up, it can drive you in the opposite direction of where you need to go.

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.
geeZ177
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5/28/2022 10:47am
Rider sag is right were ktm recommends at 105. But my static is light. They want 35 and I'm at 31.75. Also I'm 200 + gear and average height 5' 9". With the ktm springs I am at the upper end of the 4.6 spring and the lower end of the 4.8. I am losing weight daily so that should help lol. But once I'm on the bike and at the proper sag, what does static sag really have to do with anything?
aees
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5/28/2022 10:56am
geeZ177 wrote:
Rider sag is right were ktm recommends at 105. But my static is light. They want 35 and I'm at 31.75. Also I'm 200 + gear...
Rider sag is right were ktm recommends at 105. But my static is light. They want 35 and I'm at 31.75. Also I'm 200 + gear and average height 5' 9". With the ktm springs I am at the upper end of the 4.6 spring and the lower end of the 4.8. I am losing weight daily so that should help lol. But once I'm on the bike and at the proper sag, what does static sag really have to do with anything?
35 is to little, way to little. Unrideable on that chassi. Worse with 31.

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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