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2013 KTM 250SX Fork Spring change - HELP!

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Hi guys,

 

Just bought a 2013 KTM 250SX, but the previous owner weighed over 200 pounds and so it has stiffer springs on it for his weight. I only weigh 170 pounds Without gear so I want to install the standard fork and rear shock springs. 

 

I saw the video on youtube on how to change the fork springs but I read a post on here that said you don't need to remove the forks and drain the oil etc just to change the springs. Can someone post that process for me as that is much simpler and faster? That would be much appreciated. 

 

Thanks in advance!

 

 

Edited by adamdf

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You could leave the forks in place and swap springs very easily back when they were the old cartridge design, but that's not going to happen with the newer style twin chambers. You'll need to pull the forks and take them apart. If you've done seals in cartridge forks before, it's not really any harder, just different.

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You could leave the forks in place and swap springs very easily back when they were the old cartridge design, but that's not going to happen with the newer style twin chambers. You'll need to pull the forks and take them apart. If you've done seals in cartridge forks before, it's not really any harder, just different.

 

Really? I could have sworn I read a post where someone was saying you could just push up the front wheel allowing you to remove the spring without removing the tubes and emptying the oil etc.

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On the old cartridge style, you could unscrew the top cap and then unscrew the top cap from the rod/tube and then just pull the springs out, easy peasy since the springs were right there. Modern forks have the springs captured in the lower tube and you have to remove the fastener in the lower tube to get the upper portion of the fork internals out to get the springs out, this will dump all the oil out. The only thing you could do is leave the upper tubes in the clamps, but that would just make so much more work for yourself.

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On the old cartridge style, you could unscrew the top cap and then unscrew the top cap from the rod/tube and then just pull the springs out, easy peasy since the springs were right there. Modern forks have the springs captured in the lower tube and you have to remove the fastener in the lower tube to get the upper portion of the fork internals out to get the springs out, this will dump all the oil out. The only thing you could do is leave the upper tubes in the clamps, but that would just make so much more work for yourself.

 

Okay, and would I need to replace the fork seals or do they go untouched in this procedure?

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You should be able to do this without needing to install new seals. Make sure you clean the forks really well and are working on a clean surface. With the inner chamber of the fork removed, it would then be possible to slide the upper and lower tubes farther apart from each other than the normal range of suspension travel, don't do this. Keep the upper and lower tubes within the normal range of suspension travel, keep things clean, and you should be fine.

 

Also, removing the inner chamber requires a special wrench. You could maybe get away with a huge adjustable wrench, or huge pliers, or maybe a vise, but you'll wreck the anodize and it will make you wish you would have just ordered the tool.

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Its not a complex process, however it can be tricky without the right tools.

The most tricky part is having to unscrew the base bolt from the cartridge stem because it requires the fork to be upside down and you need to physically put force on the fork cap to expose the retaining nut. Without the proper tools, its very easy to scratch/damage the bottom of the cartridge. Its also very easy to damage the cartridge cap because its now upside down and you need to put a great deal of force on it.

So no, its not an easy process for someone who hasn't done it before and doesn't have the right tools.

You will need:

- 50mm WP cap tool

- Cartridge holding tool

- 19mm socket

- Adjustable wrench to hold nut

- Vice to hold assembly whilst working (though not required, it just makes life easier)

I also suggest whilst in there, to change the oil.

Here is a good break-down on how to do it, without special tools... though I've never been this successful without them before. This guy must either use very light springs OR be a beast because I can't push down hard enough to do what he's doing.

http://www.ktmforum.co.uk/technical-how-tos/51419-changing-seals-wp-closed-cartridge-forks.html

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Its not a complex process, however it can be tricky without the right tools.

The most tricky part is having to unscrew the base bolt from the cartridge stem because it requires the fork to be upside down and you need to physically put force on the fork cap to expose the retaining nut. Without the proper tools, its very easy to scratch/damage the bottom of the cartridge. Its also very easy to damage the cartridge cap because its now upside down and you need to put a great deal of force on it.

So no, its not an easy process for someone who hasn't done it before and doesn't have the right tools.

You will need:

- 50mm WP cap tool

- Cartridge holding tool

- 19mm socket

- Adjustable wrench to hold nut

- Vice to hold assembly whilst working (though not required, it just makes life easier)

I also suggest whilst in there, to change the oil.

Here is a good break-down on how to do it, without special tools... though I've never been this successful without them before. This guy must either use very light springs OR be a beast because I can't push down hard enough to do what he's doing.

http://www.ktmforum.co.uk/technical-how-tos/51419-changing-seals-wp-closed-cartridge-forks.html

 

Thanks for that tip Ty.

 

After doing some research on race-tech's website, it seems like the previous owner went up one spring rate on the forks, and at my weight (170lbs) and skill level, B/A riding motocross only, that I may be able to get away with the fork springs currently installed ( but we will see).

 

The main concern now seems to be the rear shock spring, race tech recommends the stock spring at my weight but there currently is a blue 5.7kg race tech spring installed and I think this may be the main culprit for me. There's no way i'm going to reach the right sag numbers with that spring on there. 

 

This raises my next question: What markings or numbers are written on the stock spring, the previous owner shipped the bike with a stock orange KTM spring but I want to be certain that this is the stock 5.4KG spring that I have as I know he owned a 150SX as well and am a little worried that there is a possibility he could have sent that spring instead.

 

Any help with here would be appreciated. Thanks. 

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If it is a wp spring it will have writing on the rear shock spring that says something like 54-260 and it means 54N/mm and 260 mm uncompressed length of the spring.

Ps. 54N/mm is equal to 5.5kg/mm

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If it is a wp spring it will have writing on the rear shock spring that says something like 54-260 and it means 54N/mm and 260 mm uncompressed length of the spring.

Ps. 54N/mm is equal to 5.5kg/mm

 

Thanks for posting this, this confirms that I do have the correct shock spring, thanks again!

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