Twisted development KTM 300sx

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6/6/2021 5:58 PM

I just had them build me a 300, I supplied the factory 300 kit and they assembled and decked the head for $420. This is an absolute game changer, I’m blown away with how much of an improvement this made for track riding. The only downfall I’ve found with racing two strokes against 450’s is I’m running 2nd-4th while most 450’s can just use third the entire track. Now I can roll all but the slowest corners in 3rd. Throttle response is insane, and it revs so much farther than the stock 250 did. The only downfall is I don’t see how I’ll ever be satisfied riding a 250 again, I’m gonna have to send off my new bikes right for the showroom now.

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6/7/2021 1:01 AM

Is it $420 for porting the 300 cylinder and decking the head?
Is the bike easier to ride now compared to the stock 250? I mean does it wear you out quicker?

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6/7/2021 1:47 AM

Or, just buy the TM MX300 :D

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6/7/2021 4:15 AM

So what’s done to it? Just a decked head?

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6/7/2021 7:32 AM

Really good article in MX a this month about the dicks racing 300 kit as well they rave about it just like urbanlift
Same sort of things deck the head checked the port timing etc.

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6/7/2021 11:16 PM

Yea just decked the head and assembled the motor, they offered porting and other work of course but they did not recommend that, said it was another couple hundred and really not worth it. They asked if I preferred more low end or over rev and went from there.

With it being a 300 and naturally having more bottom end I opted for more over rev. To me it’s way easier to ride as you can, if ya want, just roll third the entire track. It also comes to life instantly now, I find that much less tiresome you don’t have to rail a corner in second and bang third down the straight then back to second etc.

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6/8/2021 7:14 AM

Give us some more info on your setup. What carb and jetting are you running? What fuel, oil, and ratio?

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Powerband in every gear !

6/8/2021 7:51 AM

Stock jetting, and I run T2.

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6/9/2021 7:24 AM

I’m running a medium comp head on my 300 and it’s a nice easy mod with solid results

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6/11/2021 6:57 PM

I run an rk head also custom cut for more top end, and spaced the cylinder up 1mm. Still has more bottom than a stock 300 and feels like it pulls 1k rpm after the sticker signed off. Love it. Jetting varies depending on where I am, Jarvis carb mods (drilling out the main jet cup and baffles made a noticeable difference in top end pull). I run Sunoco 110 and the head is cut for that. I also found that I get noticeably more range than stock which is helpful off road.

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