Preparing a KTM SX 150 for enduro

I just bought a used KTM SX 150 for my 15 years old son.  He wants to go riding with me in the woods and trails (and maybe some enduro racing) but it was virtually impossible to find a 125/150 cc "enduro" used bike for him (well yes, but, a new the Husky TE 125 for 7,000 US$ plus...too much money!).

Anyway, I bought a used KTM SX 150 and my project is to adapt it as much as possible for trail/enduro riding.  I was thinking to re-gear it from 14/50 to 13/52 (thus increasing the gear ratio from 3.57 to 4, almost half turn) to increase the bottom-end.  Then I plan putting a flywheel weight (8 oz) on the rotor.  The idea is to make a much more friendly engine for long rides.

I may modify the front suspension, but I really don't know what to do there as "suspension" always has been a sort of "black science" to me.

I would be very grateful for your comments and tell me if in your opinion I am on the right path and if possible, give me some guidance on what to do with the front suspension.

Thank you!

I'm currently turning a 125 sx into a wood's bike. I also have a 200xcw to compare it to.

The suspension is definitely the most important mod to make.

1st revalve both the forks and shock,re-spring if needed. The stock sx suspension is way to harsh for the woods.

13-52 gearing is perfect. On my sx 13-50 was stock it works fairly well to.

The 2nd big issue I had was the carburetor. The 38mm carb sucks for woods riding. Very poor off idle response and easy to bog.

I could never get the jetting dialed in .

So I put a 36mm carb on and it helped a lot . If you're 150 has the 36mm carb then just jet it to work better in the lower rpm range.

I would also say try it without a flywheel weight, I don't think you need one.

Get a skid plate,hand guards and a spark arrestor if needed and you should be set.

I had 2.5 weight fork oil put in my forks, made a pretty big difference. The bike tracks better and handles chop great.

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