Hello everyone!

I have searched for an hour now.....

Bike = 2006 KLX 250

Good News: 300 kit was successfully installed, and the bike runs!

The Not So Good News: Around 4000 rpm bogs badly, and pops really bad on deceleration.

I have: Supertrapp exhaust, NC1 needed second clip from the top. 122 jet.

What should I do with the fuel screw?

I am a real newb when it comes to tuning, so any help / advice would be great.

THANKS!

 

See where the fuel screw is now, don't seat it hard though. About 2,1/2 turns out is a good start I think. Try that before you do anything else. Your bike sounds lean so you want to try to change that. Maybe raise the needle one position.

 

+1 for lean, i wont know much more on tunning till i get my tax returns lol

 

I'm curious. I have an '06 KLX and did the 300 jug. Did you have all the mods you listed before you installed the 300 jug? I had a full Muzzy exhaust, opened up airbox mods, and Dynojet modded carb when it was a 250. It ran perfectly. I thought I'd have to do some carb tweaking when I installed the 300 kit, but even after going up on the main jet and experimenting with different needle positions, I ended up with exactly the same jetting as when it was a 250 with the same mods. This is not that unusual. So, I'm asking if you already had your bike set up in the same manner as it is now with the 300 jug. If you did, perhaps something else is amiss...unless it ran like this as a 250 also. The 300 jug does wonders for a noticeable power increase, especially at low and mid-range throttle positions, but I don't it affects jetting that much if any. And I also get extremely good mileage with my bike.

If your problem is jetting related, it sounds like the problem is within the needle position and main jet areas of influence...at least the 4000 rpm issue you mention.

 

mods were done before the 300 jug.... I am going to adjust the fuel screw 1 turn out tomorrow to make a richer mixture.

I will update.

 

That should have no effect on a bog at 4000 rpm.

 

The fuel screw is in the pilot circuit of the carb and is in parallel with the pilot jet. The two of those control fuel flow at idle to about 1/4 slide opening. Your problem sounds more like the needle position and/or main jet and the passages that the fuel flows through from them.

Ride on
Brewster

 

I moved the fuel screw out like 3.5 turns and I went down one notch on the NC1 needle. The clip is now in the middle of the needle.

I found that I have a 40 jet and a 122 which I swapped in a while ago.

It runs better, but it almost feels like it misses at 6500 rpm.

Any other thoughts?

 

Sounds like it's still lean. Up the main jet (keihin) to 128 or 132.

 

That could be the "better ground for the regulator" issue.