Super Noob here- Take it easy on me. So after melting the corner of the airbox on my 2009 KLX 250S , I eventually realized that the PO had put the wrong FMF Q4 Slip on on the bike. He had put one on that was intended for an '06, and after talking to FMF, it sounds like these two have different bends. Found an airbox used on ebay for $50, and have the new Q4 on order. I have never looked to see if the PO had rejetted the carb after taking the airbox snorkel off and putting the FMF Q4 on. Spark plug is black, which contradicts my thought that it was running too lean (exhaust getting so hot). SO my question is, do you guys suggest a jet kit, or will I be able to just adjust the needle and use the same jet that came stock. It will be my first time diving into a carb. A little intimidating. Any thoughts?

 

...And I ride at an elevation around 1500-2000ft.

 

I used the Dyno jet kit. The instructions are easy and will walk you right through it. My bike runs perfect @ sea level.



Also deleting the air injection will lower exhaust temperature. Mine is still hooked up and no airbox issues.

 

The stock needle is not adjustable. Get a kit.

Ride on
Brewster

 

In regards to the melted air box, my Q4 was a TIGHT fit as well. I silicone some hi temp aluminum foil against the airbox and it's been fine so far. But yea, was 2 - 3mm of clearance if that. I know others have had issues as well so I don't think it's a year/model mismatch thing specifically.

DynoJet kit is 50 bucks or so - pretty hard to go wrong and there's a bunch of proven set ups kicking around (mine in my signature).

You can also save 10 bucks or so and go with the OEM Kawi needle (N1TC), it's adjustable and then find an OEM jet that's the right size for your elevation (klx678 or someone else might be able to speak to that, I'm not much of an N1TC tuning guy).

 

Thanks Guys. Got the Dynojet kit, new can, and heat tile all on order. I'll let ya know how it goes!