I'm considering modding my stock 2009 KLX250. I am 200#, and looking for more power and better suspension for aggressive trail riding here in the PNW. Currently not enough power on the uphills or throttle response out of the corners, and the suspension bottoms and wallows.

After digging around here it looks like Race Tech is the way to go for suspension and B & B cycle for a 351 kit. Anyone or anything else I should consider? Or would I be better off looking for a different, bigger displacement bike with better suspension? Not sure I would need to go all the way up to a 450 - my last bike was a modded YZ250F that go the job in the woods done just fine - wasn't street legal though. Would like to make my KLX work if it can.

 

That's a delimma. Pump lots of money into a 300, or get a larger bike for lots more money.
If I was in your situation, I'd simply get a larger bike with everything that matches already on it from the factory.
But if you can do mechanical work on bikes yourself, you might enjoy making a fun project out of it.

 

That is the dilemma. I would do the work myself, so I would save on some labor.

The big bore kit is $575. I’m not sure how much the suspension is. Maybe $1200 total for everything? The bike is maybe worth $3000. So total value $4200? Would the B&B 351 with Race Tech suspension tune make the KLX as capable as a factory woods 350 bike? And could I find a factory ready machine for $4200? (and licensing etc would add 10% tax and fees here)

 

You could go budget and get the AHL 299cc kit for under $200 on Amazon, pick up a Mikuni TM36-68 flat slide pumper carb for around $270 for much quicker throttle response. Check out D. Pippin's web site at KLX250S Home Page He has the work noted. He or TNC may have jetting suggestions for where you are located. The rear shock has the capability for revalving to work near on par with a high buck shock, same wit the forks. Personally, after finally retiring and having no more excuses I will be fitting my 299cc cylinder and flat slide on my 09 KLX this summer.

But you won't get KTM race performance and I doubt you can find a decent 450 KTM dual sport for four grand that doesn't need some work. But I could be wrong. I know TNC has stated he has no problem running around Utah with the KTM boys. Maybe he will post up here.

 

I'm glad you chimed in.
I have zero dirt experience and can only comment generally on the choice of buying or building. Buying a complete bike has an inherent advantage of being factory engineered as a complete wholistic unit. But that's not to say a rider couldn't improve on it.

 

I saw that kit on Amazon - wasn't sure about it because the price is so reasonable - good to hear a good review. Thanks for the link I will check out Pippin's build. May be the way for me to go.

I probably don't need a full blown woods race bike, just more power and suspension than my KLX is currently offering. The used KTM 350's go for $5k and up here. I'd need to add lights and licensing plus title transfer and tax so another $1k probably all in $6000 starting for a KTM350 level bike.

I have some more research to do now.

 

Your 200# and have never resprung your bike? I think the KLX is sprung for someone about 155#.
Get rid of that CV carb and get a flat slide would be the first thing to do and you wouldn't have to pop open the engine.
It will be a nice trail bike, but it will never match a 2 smoker racer. If that's what you want research plating and moding a racer, but it's going to be expensive.

 

Is this Amazon source a legit and reliable source for the Mikuni?

$247.00

 

I'm 135 and the stock suspension is stiff even with lowering links and the lockrings on the rear shock spun up to the top.

That's the big issue:

How much performance do you want and how much are you willing to pay for it?

Every biker addresses that in their own way.

 

Totally true. This is the hard part - figuring out how much is enough without being able to test these upgrades prior to spending the money. The reviews and experience here are helpful in figuring it out.