What jet kit company is the best? Also, I have a 09klx250sf and i'm not sure what kawi dd to make it's engine such a *****, but I don't like it lol. How can a 4stroke dirtbike with the same size engine have more than twice the horsepower of the sf? And how do I get it back to the horsepower it should have(around 50hp)?

 

4 stroke 250's don't make 50 HP, 2 stroke 250's do. The majority of performance enduro and MX 4 stroke 250's will make between 28 to 35 HP.

What source for your figures?

As for the jet kit, they're all made by Dynojet just branded JD or FMF etc. The 2206 kit (KLX300R stage 2) will give the best start to gain some more HP if you intend to modify the stock bike. (BTW the most serious KLX250 I've read about was making 40 RWHP and was campaigned and won the AUS Thumper Nats series in 2000. This engine in 250cc form will never make 50HP. Get a 2 stroke if that's what yo want. The new KTM 250SX makes 49 hp stoch off the shop floor.)

New muffler, jet kit, new (free flowing) air filter will be a good start. Should get change from $250 if you know your way around the interbaynetbook thingy.

 

I still don't get why people expect a street legal 4-stroke single to be some kind of fire-breathing monster right off the floor...and I mean a real street legal one, not a race bike that "can" be run on the street. Bikes like the DRZ400, WR250R, and KLX250 are bikes that do quite decently off road and can be driven a good deal on pavement without lots of wear and frequent service issues. And I'm not bashing those more aggressive dirt bikes, but you really need to know there's a difference between these types of bikes. If horsepower is your only priority, then your choice is easy. The KLX250, WR250R, and DRZ400 are all "corked up" to some degree for emissions, sound, etc. They are relatively easy to uncork to get a noticeable gain in power. I notice some states are starting to refuse some of the KTM's for street legal designation, and that's unfortunate.

On the rear wheel horsepower deal, I notice a Thumper Talk thread where a guy tested his KX450F and got 46 or 48 horsepower with an aftermarket slip-on. WOK, was that KTM250 horsepower at the crank or the rear wheel?

 

That info was just from a quick google search, and a friend agreed about that, but he prob doesn't know much more than me (which is basically nothing when it comes to bikes) I just expected better because the guy at the shop said it will do 80mph stock, and with an aftermarket exhaust it's hard to get it to 60mph.

Why is the klx300r jet kit better than the one that was made for the klx250sf?

 

2strokemotocross.com. The SX 2 strokes from KTM do come in a very high state of tune. Horses for courses really. The 2011 apparently makes more HP than the 2010 model (gulp) and the 2010 dyno result would indicate RWHP (Usual Dyno test.)

"Q: HOW DOES THE 2010 KTM 250SX RUN ON THE DYNO?
A: It’s a rocket ship! This is the most powerful 250cc motocross bike sold. On the dyno, the 2010 250SX made 49.05 horsepower at 8600 rpm and 30.95 foot pounds of torque at 8100 rpm."

The full article is here.>>>>http://twostrokemotocross.com/2010/0...sx-two-stroke/

 

WOK, sorry for my lack of attention. I see now that was a 2-stroke. Thanks for the info.

 

More aggressive needle taper (kit 2206) which translates to more fuel in the med to WOT (Wide Open Throttle.) The KLX likes a lot of fuel in the upper RPM range and the 300R needles abrupt taper reflects this. The needle in the sf kit will work and will still add some gains over stock but IMHO is outperformed by needle in the kit designed for the 300R.

 

Oh ok thank you. When my paycheck comes in I think I'll get that one. Also what are the rpms the klx likes? Like 6000-8000?

 

80 stock? Who wants do do 80 on a bike that gets blown around when a Ford Focus passes them? No thanks.

 

Im coming from a streetbike to the sf. And i love it. is it down on power of course. If i wanted more power/speed id go buy another streetbike. and before id spend 6-7k on a husky, ktm, etc id rather buy a streetbike. I paid 4k otd for my sf brand new. ive put maybe 500 into it. and i couldnt be more happy. Get a jet kit and get it tuned properly it will give you a whole new appreciation for the bike.