Over the last few days I've put the new FMF Q4 on and the K&N air filter. Yesterday I took the bike for a 40-mile ride and it ran perfect. Today I got the KDX snorkel and replaced the stock one. After replacing it the bike ran horribly. It was very jerky at anything over 6,000 RPMs. I stopped and put in half a tank of 91 octane hoping that would help, but it didn't.

It hasn't been re-jetted and the idol is set the same as when I drove it off the lot. I was hoping to get it re-jetting when I did the 600 mile service. But now I'm thinking I might have to do it sooner unless I can adjust the idol to help.

Hopefully someone can advice me on the best way to address the issue.

 

New high performance free flowing exhaust with increased air intake............you need to rejet, period.

 

You made a substantial increase in air flow with the filter-snorkel - muffler. More air without more fuel = too lean. Order up the dynojet kit, not too hard to install yourself. In the mean time put the old snorkel back in.

 

Time to rejet.... DynoJet Stage 1 & 2 Jet Kit for Kawasaki KLX 250 S 09-10

 

They come tuned pretty lean, opening them up makes it alot worse. Don't wait to long to richen it up some.

 

Lean starvation.

Also, unless you change your compression ratio, don't waste your money on anything higher than 87 Octane. "Octane" is NOT a quality rating, it's a rating related to the tendency for a fuel mixture to detonate prior to the spark plug firing. SOME higher octane fuels use additives that can actually contribute to soot buildup in the combustion chamber...which makes them lower quality than a less sooty fuel that has a lower Octane rating.

 

Liar !!! Oktaine = whorespower

I poured some NOS energy drink in the tank of my GSXR with the 110 oktaine aviation fuel and i was doing 200 mph 8th gears wheelies.

 

Thanks guys. I'll either cover some of the opening of the KDX snorkel with electrical tape or put the stock one back in until I can get it re-jetted.

I tried going to that jcmotors.com site to look for the Jet kit but the site is down. Any other suggestions. I'd like to keep this as simple as possible.

 

You're in too far to keep it simple now!

You can also order DynoJet kit directly from the manuf, or maybe from a local dirt bike shop. Or you can get the Kaw parts and keep it green.

In the meantime, plug up some of your air intake like you mentioned and save your piston.

 

When my bike is running lean, I get some exhaust popping at strange times when decelerating but the obvious way to tell for me is the engine runs noticeably hotter, around town & on longer runs.