I have a really nice 2009 KLX250s, jetted, pipe, cam timing moved, great shape, I really like it. My buddy wants to buy it. So I’m thinking about the ‘24 300s. Money not an issue.

is a stock 300 as fast as my modded 250? Because for what it is it runs right along. Just went an indicated 80mph and still climbing…..

The 300 is fuel injected of course, what happens if you take the lid off the air cleaner and put on a aftermarket pipe? Do you have to reflash it?

Thanks in advance!

 

You might be able to make a rough comparison if you have any dyno information either for your own 250 or for a similar one.
This is a dyno test of my 300. It was completely bone stock with only a slip on exhaust.

25 HP
16.5 TQ

 

Tooter, thank you for the reply, with just a slipon, did it run ok without a reflash?

 

It ran fine.
With the restriction of the stock airbox and snorkel it was impossible to get more air to lean out the mix.
The stock O2 sensor automatically corrected for any minor differences caused by the exhaust.

 

To shorten a long story, I sold my 250 to my friend and found a ‘23 KLX300D with 400 miles on it. The fellow that sold it to me was not the tallest guy and the seat height was beyond his comfort zone.

After some adjustments, I have formed in opinion about my moving up to the 300 from the 250.

My 250 was fairly well modified, no airbox lid, rejected the carb, moved the cam timing and installed an aftermarket silencer. And I should mention that it was a silencer in name only.

After riding the 250 for a lot of years, and now riding the 300, you wouldn’t think there would be a lot of difference, but there is. The fuel injected, 300 runs a lot nicer than the 250, the 250 might’ve had more power in the mid range but when the 300 is wound out it goes really well, 75 to 80 mph down the four-lane is very doable and it has some left.

The 250 on the other hand was pretty well out of gas by the time it hit 70, and if you were riding into headwind or up a steep hill, it did struggle a bit. The 300 is obviously what they originally designed the motor to be, albeit carbureted, but the fuel injected 300 is just a nicer engine to ride. It does vibrate a little bit more than the 250, but not objectionally

My plan is to pretty much leave the 300 stock, but I might remove the second butterfly in the throttle

My new to me KLX300
body. That should recoup some of the mid range that I think is missing. The other modifications, though expensive don’t sound like you get much for your money.

i’m glad I upgraded to the 300, I really like it and it goes well with my seven other motorcycles.