525 SX in the woods. Help!

I have an 04 525 SX. It has the 6 speed transmission swap done. It is converted to street, and is legal. It works awesome on the street, especially in SM trim :ride: Right now I have the stock wheels, full knobbies mounted up, and 15/48 gearing. It still works great.....except in the bush. Abruptly stalls a lot! I notice it's mainly when cresting a hill. I get near the crest, the bike slows abit, I back off the throttle somewhat for a moment, then try to get back into it, and it's there where I stops. Almost seems to flame out. I have to pull the hot start every time, and usually takes a few kicks to get it going again. I imagine that the small SX flywheel has some role in this, and I do turn up the idle when I go into the woods, which does help, but I would like better. Would adjusting the fuel screw, or rejetting the pilot circuit help at all. What about dropping a tooth on the counter shaft sprocket?

If you've still got the close ratio first gear (as opposed to the EXC first gear) then I'd definitely drop a tooth on the front. Also, I use a tach to set the idle on my '06 450 SX, as the recommended setting of 1800 rpm (for trail riding) sounds way too high if you're just going by sound alone.


Regards the low rpm idle speed for trail riding, I'd read on another KTM forum that the auto decompression will actually kick in if idle speed is too low, causing these flame outs.


Once I got my bike geared right and started setting the idle speed by a tach (at 1800 rpm), it worked much better for woods riding. But, I still rode it with a finger or two on the clutch, just in case.



Thanks for the advice. Regarding the finger on the clutch, I have tried that, but it just happens way too quickly. And about this clutch...this is the first dirt bike I have owned with a hydro clutch. Any way to set it up better? It's pretty much either in, or out, and it's right at the beginning of the lever travel. It's like a cable clutch, that's adjusted a little too tight

If you are running the close ratio 6 speed you will have to drop the gearing way down for the trails, i.e. something like 13/50 or even 13/52.  If the trans is the wide ratio 6 speed 13/48 should work OK.  

How can you tell the difference between the close, and wide? I bought the bike with the conversion. It does have a pretty long first gear. ALSO!!! I have just realized, that this bike is getting a little harder to kick over recently when warm. Any way to adjust the auto decompress?

05 450sx with the 6 speed tranny here myself. 1 thru 4th gear is close-ratio, 5-6th is wide ratio. Had the same issues as you, went with trailtech heavy wt. stator. It helped alot in the tight stuff- ride the woods of Oregon. 13/52 gearing will make a big difference also as mentioned before, am running it currently.


I'm running a 450 with 13 52 gearing and 6 speed wide tranny. Never stalls.  I think the secret is the 13 52 gear set.  It has the pull of my John Deere.

13/52 would probably kill the gearing for the road

13/52 would kill the engine on the road is wat too close for street. I have a 450exc with 13/52 for tiral riding and is ok will go to 12/52 while we ride extreme hard enduro and driving i 2 gear or even in 3 gear make a huge difference in wood. For street use i ride 13/42 and its for 450 perfect.

14, 48 myself. Properly adjusted valves, and jetting is key. If getting hard to start open up the head make sure your valves are good then tune the carb.

Bike starts good cold, even starts good warm. It's when its pretty hot, after riding slow in the bush that it can be hard to start.  I'm finding tecniques to fire it up quicker though

Bike starts good cold, even starts good warm. It's when its pretty hot, after riding slow in the bush that it can be hard to start. I'm finding tecniques to fire it up quicker though

Valve adjustment. No brainer. Should take you 20 min. Your bike should start easy warm or hot. Ur supposed to check/adjust these least every 20 hrs depending on abuse.

I've got an 05 MXC 450 dual sport and run 13/51. Tight woods I run a 12 and that really brings down that tall first gear.

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