Who has one? What mods work the best? And want to do a rekluse clutch in it. I have a four gallon tank on it now. Has the stock four speed box. Thinking about the close range 5&6 gears. Any takes on this? This is my first bike build. Just want to do it right. Thanks
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2003 ktm 525sx snowbike build
- Thread starter Curt_T
- Start date
Sx525
Did my exc 525 up last year ,570 kit stage5 cam ,ported an mxc trans also have the recluse clutch .,it's nice but not must have had to put 9 tungsten balls in it to get it to hold an not slip ,the trans was a big plus over exc trans
Did my exc 525 up last year ,570 kit stage5 cam ,ported an mxc trans also have the recluse clutch .,it's nice but not must have had to put 9 tungsten balls in it to get it to hold an not slip ,the trans was a big plus over exc trans
R
Rush44
Well-known member
My buddy just picked up an 03 525sx... couple things you should know:
1. The 525sx had a factory recall for the CDI. The problem was the original CDI allowed for the bike to over-rev too much causing valve train failures. The part number you want on the ECU (the updated one) is 590.39.031.100 in combination with an adapter 590.39.033.000 (Dummy TPI sensor). The 525sx has steel valves instead of titanium and can't pull the high rev's of the 450 motor the 525 is based from. The CDI box update lowers the limiter from 10,800RPM to 10,100RPM. No other changes.
2. The added 5th/6th gears are very tall if you decide to add them. When I rode his bike this weekend I couldn't tap out 6th hardly on a long downhill dirt road with about a 3/4 mile run out. I doubt you would ever use 6th on the snow... 5th when you are down the road and already hauling ***. First bit of pow you hit you'll most likely have to downshift to 4th. The 4th to 5th jump is pretty wide.
3. The electric start kit for $700 is probably a good idea. We've both had a hell of a time starting this bike when it gets warm. We had to resort to bump starting it several times and that kick start is hard as hell... one of the hardest I've ever encountered. You need to get good with that decomp lever timing.
4. I'm not sure what the stock front forks have for springs/oil, but the valving seems very soft for stock. Prepare to upgrade those forks for winter riding. You will want something stiffer.
5. Write down Timbersled's fit kit number since their website lists it wrong. The correct fit kit is SB-563.
Based on these issues my advice to him was to sell the 525sx and find a different bike if all he cares about is snowbiking. It does seem like it would be a great off road bike in the summer minus the starting issues.
1. The 525sx had a factory recall for the CDI. The problem was the original CDI allowed for the bike to over-rev too much causing valve train failures. The part number you want on the ECU (the updated one) is 590.39.031.100 in combination with an adapter 590.39.033.000 (Dummy TPI sensor). The 525sx has steel valves instead of titanium and can't pull the high rev's of the 450 motor the 525 is based from. The CDI box update lowers the limiter from 10,800RPM to 10,100RPM. No other changes.
2. The added 5th/6th gears are very tall if you decide to add them. When I rode his bike this weekend I couldn't tap out 6th hardly on a long downhill dirt road with about a 3/4 mile run out. I doubt you would ever use 6th on the snow... 5th when you are down the road and already hauling ***. First bit of pow you hit you'll most likely have to downshift to 4th. The 4th to 5th jump is pretty wide.
3. The electric start kit for $700 is probably a good idea. We've both had a hell of a time starting this bike when it gets warm. We had to resort to bump starting it several times and that kick start is hard as hell... one of the hardest I've ever encountered. You need to get good with that decomp lever timing.
4. I'm not sure what the stock front forks have for springs/oil, but the valving seems very soft for stock. Prepare to upgrade those forks for winter riding. You will want something stiffer.
5. Write down Timbersled's fit kit number since their website lists it wrong. The correct fit kit is SB-563.
Based on these issues my advice to him was to sell the 525sx and find a different bike if all he cares about is snowbiking. It does seem like it would be a great off road bike in the summer minus the starting issues.
Did my exc 525 up last year ,570 kit stage5 cam ,ported an mxc trans also have the recluse clutch .,it's nice but not must have had to put 9 tungsten balls in it to get it to hold an not slip ,the trans was a big plus over exc trans
Steve how has the big bore held out? How well dose it pull 5&6 in the dirt and snow. Any issues with the clutch and which one are you running?
Rush44. Thanks for the info. Plan on using this bike for one season and getting a brad new power plant for next year and going all out with one. This bike is a monster in the dirt and power that never ends.
Big bore held out just fine rode hard all last winter still good for next ,the 5th -6 th where good not as much top end as the exc ,but 1st- 2nd way better would of liked to have more top end for on the trail but the close ratio was much better in the trees