I have had my KLX for about a month now and really got it out for the first time this weekend. I did some of the performance mods: KDX snorkle, drilled slide, installed N1TC needle, clip, and collar, installed #125 main jet from Kawa, and went to the #40 pilot jet, also installed FMF megabomb with Q4 exhaust. Fuel screw set 2 turns out.

I rode both saturday and sunday. Both days were basically all trail riding down in KY on S-tree, Turkeyfoot, and Redbird crest. Saturday I hit reserve at 47 miles and put the bike on the trailer at 52, whin I fueled the bike up I put in 1.85 gallons (just about out). So thats 28 MPG. Sunday morning I took the air box lid off and rode without it as I was thinking maybe is was not getting enough air flow. I also checked the air filter and there was nothing unusual with it, a bit dirty but not terrible. Sunday I hit reserve at 52 miles, I have not filled up yet to see how much I put in but I still don't think I am getting much better than 30 MPG.

Now I know I was on trails and that performance mods will affect fuel mileage, but it shouldn't be this bad, I was expecting to get 45-50 even with the mods. Where should I start? What should I check and look for?

 

Wow that's low. I thought I was getting bad mileage, on average i'm getting 75m (120ish km) before hitting the reserve riding hard. This is with the Asian fuel injection model but I have got it running pretty fast (de-restristed etc) with most mods except a big bore or cams!

 

Landon,
I'll venture that your pilot jetting at least is on the rich side. Can you adjust the fuel screw while the bike is running? If so, that can help you determine if you have the correct pilot jet size by finding best/highest idle, preferably with screw between 1 & 3 turns out. When my pilot was too rich, I could turn the screw nearly all the way in with hardly a difference in idle speed.

I did mods similar to you and went #38 pilot, DJ needle clipped 3rd, and DJ 128 main (which if the conversion chart is correct is close to a 137.5 Keihin). Mileage was close to yours as I could get below 30 on the slower tough trails and into the upper 40's on the street (I also geared down to 13/49). Rejetted to #35 pilot (stock), clip 2nd, 124 main and haven't got below 30 since with most 45 mpg or better. My lid is off and elevation is generally 3000 ft +.

 

I bought the kuoba screw, so I can adjust while the bike is running. I just rejetted off the suggestion on these forums. A buddy actually did the work, could the clip in the wrong slot of the needle be a culprit to this? I am not that familiar with the workings of a carb myself as I have always had FI bikes. Are there any hoses that might have been undone with the carb was removed that if not hooked back up could cause it?

 

That's really low! 60 mpg is what I get with jetting and what not. Thats messed up.

 

I assume when you say you get 60 mpg that is on the street and not on rugged trails.

Sounds like I need to really top the bike off and go for a street ride and see how I do. Maybe something around 30 isn't all that odd for trail riding where your using alot of throttle and not really going very far.

 

Pilot and main jets, clip position, air box config (lid on/off, snorkel in/out) can all be issues. Also float level as mentioned in other forum. I'm not sure about any of the vent lines being an issue, but I'd check them anyway.

 

also get 60 mpg with jet kit, k&n, kdx snorkel, FMF exhaust and 15T front

 

You dont ride it hard enough.....

 

Well at 60 mph and 7 grand, that's still what I get on the highway. Its gonna get even better on the trails since I don't ride at 7 grand on any trail. And according to most people because I don't wreck I don't ride hard enough....whatever