2010 reliability(450-250)

Just curious,before i actually buy either bike,,,how reliable are these bikes?? Am i gonna be doing top ends all the time(halfway fast beginner)?? I do hare scrambles and mx,have been on ktm 300 and it just doesnt do it for me on the mx track..Im looking at both a 10-250f(kawi),,and a 2010-450f..be honest with ya, i dont know which would be best.i just dont wnna get wrong one.Ive heard the 250f's ya go through alot of topends..And the 450,well its a handfull in the woods.Both bikes have around 20 hrs and are in same condition and price.I know this should prob be in "what bike to buy" section,but i fig that the brand specific section may have usefull advice also!! Thanks...

On an MX track, I'd estimate that a typical pace rider would use a 250F at double the revs and 4 times as much throttle opening as a 450. So they get worked a lot harder.

I don't want to start a debate, but I'd say my 450 engine has been cheaper to run in the past 5 years than either of my friend's 250 2 strokes. All bikes done about 300 hrs. 2 strokes are great. But my point is that 450s typically dont get worked that hard. When I ride a 250F I feel the need to wring it's neck all the time, so I'd be spending a lot more to keep it running.

You decide.

i had an 09 KX250F for a year, in 150 hours i had to replace the valves 3 times, two pistons and by time i lost it the big end had started to develop some big end play so it was in need of a big end, was it reliable? yes, as long as you performed all the preventative maintenance when ti was due.

also my riding is all trail riding and A grade enduro with a hand full of B grade mx club days.

Dang,250 sounds outta the question..lol.No faster than I am, the 450 may b a better choice.And there will be alot of rooom to grow..I'd prob never ride it to its potential,but it'd be fun trying!

Yeah, 450 engines are typically reliable. To hurt one in typical amateur MX conditions, you either have to be real unlucky, or else really push it with a lack of care or maintenance.

I have friend's with '10 KX250Fs, and I really love riding them, but if I rode one all the time, I dont think I'd have the time or money to keep it going. As an extra bike for low hrs use, no probs with a 250F, but as a work horse I think it's either a 450 or else a 2 stroke.

450s can be awesome fun for the cost of running one. I'll share some of my passion for riding my 450 and a few others:

The thing about them, any make or model, is that you can take a corner basically two ways.

1) Dive in, brake, pivot, point to the exit, then use the motor to make up for the speed loss. Typical "lazy" 450 riding. You see the pros to this at times, but only when they enter a corner way too fast for whatever reason. The pivot part is boring and seems to take forever. Plus I don't get much fun watching riders who are heavy rear brake users.

2) Plan to flow with the power on early. Pick a line, pick your speed, pick your lean, front tire placement (when necessary), and then dial the throttle open. Sounds like a 250F technique, but there's less room for error because you commit to it, and what starts ugly often ends ugly. Get it right and it's the best feeling - to let the rear tire eat while you expend little effort. Get it wrong and you'll find the 450 will not change lean or line very easily, so you push wide, or drop it, or cross rut and crash or whatever.

Sometimes the motor response and power is too much. An ECU "remap" (or adjustable CDI for carb bikes) can tame it down a lot. But on typical tracks or technical offroad, the setup of a 450 MX bike is more important than for any lighter/smaller or less powerful bike where you can just muscle the bike to behave. 450 MX bikes (esp the 06, 07 or 10 KXs) can get away from you, but with good setup you can use more motor with much less effort. By setup I mean the usual: springs, heights, dampers, bars, gearing, controls, linkage, etc). Some people think screw all that, but 20% effort gets you 80% of the benefits.

I have found a 450 is much cheaper for me to maintain than basically any bike. When I was racing seriously I had a 250f, 250 smoker, and a 450. I rode both 250s HARD and had to rebuild them constantly, I even managed to crack a cylinder on my 250f one time...450's just chug along. No need to over-rev them

great thread so far - thanks!


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