Hello again, I keep hearing all of this back and forth argument about whether it is ideal or not to even put on an aftermarket header on a KLX. I've seen some argue that it kills low end torque, and others say that it just increased it across the board. I was looking into the PowerBomb header by FMF paired with a PowerCore slip-on. I don't plan on installing a bore kit if that's a factor.

 

It's not going to decrease any power, it's a matter of how much you gain for the cost. From what I've read I'm sticking with my stock one.

 

didn't notice any power gain...fmf powerbomb header...did notice noise reduction and better throttle response...reduced decel pop...

 

I'll probably just buy the slip-on and see how it goes, and than decide whether I want to cough up the cash for the header. And does anyone know the difference between the Q4 and PowerCore Slip On? I only really heard about a mention of the Q4 having greater noise reduction, but nothing about performance. Think it's really worth spending the extra cash on a Q4, considering that I don't really care how the bike sounds so long as it's loud enough.

 

I noticed a significant difference after installing the header. The stock one is just too small for a bike this size.

 

Make sure the slip on pipe fits OVER the header at the join between the two. You do not want restriction at this joint. No use if the slip fits inside the header and uses the thick OMC gasket packing. This will just reduce your airflow and restrict as per standard header.

As far as performance gains, mmmmm. I fitted the PowerBomb plus Leo Vince muffler and modified slip on to the 250. Maybe a bit more snap all round, but awsome sounding.

I then went with a 300 OMC kit, which costs less than the header and slip on.

Big difference. Roll on wheelies in second, pulls like a train up mountain passes.

The big bore is by far better value if you want power gains, but hey, a pipe looks good.

 

I did the powercore 4 first and it was far better than stock, I then jetted for my pipe and I couldn't tell it did anything at all but I lost all popping on decel., then I added a power bomb and it added grunt right off idle that was missing, made it alot easier to get the front end up in low rpm situations. Your results may vary.

 

When I installed mine...I did notice it got some snap back in it off the line,also sounded better...I got my whole system..Header/slipon/kdx air/fuel screw/jets...brand new in the box for...get this $280..CL..second day I had my bike.guy had two sets, and two new bikes,for sale...bikes were gone in a heart beat,$3500each..and get this...they didn't want the Kits...score

 

Back when I was selling bikes, the KLX300 gained the most by doing two modifications. One was a full exhaust, the other was to go to a slide carb for the bike. It made significant gains. The combination lets the engine breathe freer. Is the same true on the KLX250? Ask TNC who has, I believe, had expeirence with both the 250 and 300. If I scrounge up a few hundred I will try it on the 650, because I was amazed what simply pulling the snorkle and installing a pipe did to it, then the big bore... a carb might just pick up a significant bit more.

 

Full Muzzy, jetted, uni air filter... made measurable difference throughout the range.