Hey guys I've got 1200 miles on the KLX and have noticed that when I start the bike and it has been idling for a minute or two while I finish getting my helmet and gloves on and shut/lock the garage door, when I get on and rev it a few times to say 3-4000 rpms the first 2-3 twists will get some blue smoke out the pipe. At first I thought it was crap inside the pipe because I bought it off a KLX300 that lost its compression and the pipe was a bit oily but now I've got a few hundred miles on it. The oil was changed at 250 miles, 600 miles and I'm going to again when I get back from vacation in a week and a half. I broke it in sorta in between the book and the mototune method, pretty much I took it out and rode it the way I was going to anyway. Trails and some road jaunts varying between the gears and varying rpm the whole time, runs up to 6500-7000 but once I got there I'd let it coast back down, go down a gear or two and run it back up. I'm not overly familiar with full size motors but I've been tuning/rebuilding tweaking the 10th scale ones in my rc trucks, however those are 2 stroke and make 2.5 horsepower at 40,000 rpm so its a bit different considering its only .18 cubic inches (3 cc's).

 

Could be running a bit rich. Check your spark plug for the signs.

 

I checked it about 75 miles ago and it was a chocolate tan, borderline Hershey bar. Which is a tad on the rich side going on the sparkplug scale. So I rode for a bit the other day with the snorkel off and man did it ever pull hard but from a brisk run up into the higher rpms and then backing out of it for a corner or other obstacle it would let out a very audible exhaust pop, not the usual burble but a literal crack. It would not do it under 6K but if I made it up to 7500 at a minimum it would pop and crackle on the way back down, especially so if I was low in the rpm range and gave it a wristful to get up to speed. With the air screw at its current position I only have to pull the choke out partway to start it and can release the choke as soon as it fires. Here's the catch, I've been reading online and have a post from the f650 board in my other post that states that such an exhaust pop can be caused from the smog crap installed on those bikes as well as having an air mixture screw thats in too far. I had my mixture screw at 2.5 turns but it was so rich that it would start without the choke, however after riding a few miles, when I would stop at a stop light the idle would gradually get lower and lower and lower. So I set the idle speed when it was warm to ~1300, however when the bike was cold it wanted to idle at 2000 or higher. Right now I get a consistent 1300 rpm idle except occasionally it will sit closer to 1800 and a little twist on the throttle to bring the rpm up a tad and it will idle right down to 1300.

 

I've got the same symptom on my bike, does not really have a decel pop but when I shut the throttle closed I get an audible pop or cackle right on the bottom. My jetting specs are all the usual mods with 300 head/exhaust pipe, 40 pilot, 132.5 main, lid removed, 2 turns out. I had the carb all the way off today and cleaned it out, checked the jets, my next move will be to take off the smog junk. Otherwise the bike runs strong besides the bottom end pop/crack.