Videos are probably long gone since this thread is over four years old.

 

I did not take notice of the post date. Now I feel like an idiot.

 

You're not alone

 

Hmm... Well seeing that I appear to need a higher octane fuel I'm a bit worried now. I hope it hasn't caused some sort of damage while the engine is breaking in.

The sound is consistent, though it does seem like it's starting to lighten up a bit now that I have 100 miles on it. I've been using regular 87 octane, anti-knock index 2.0 fuel like the manual states (even though the information on the rear left fender says to use 91 octane fuel). I have been using an additive octane booster to see if it will lighten up the sound since I first got the bike because of the compression ratio. Being a little on the high side for normal octane fuel I figured it would be best to add a little extra in.

What does everyone here run? Is it pretty much a requirement to run premium in this bike? I just want to be sure I'm not damaging it by running it with the knock going on. It's "really" hard to avoid making it knock when I'm trying to adhere to the <=4000RPM limit for the first 500 miles of the break in. There's a lot of hills around here, so it gets load put on it a lot.

Does it make a noticeable difference in the sound when you have switched from regular to premium? Or does the sound pretty much just the way the KLX engine is. I just want to pull as much information as I can, because getting this bike serviced from where I am will be extremely difficult if something goes wrong from the fuel. I'm on a remote island in Southeast Alaska. It took two weeks and several barges just to get the bike here, so the better I can figure this out before a problem develops, the better.

I'll get some premium here in a week or so when I can and see if it improves it at all. I appreciate the feedback very much.

 

read thestill ticking thread...you'll be glad u did.

 

The stock KLX250 or even the 300 should be able to run on most regular unleaded fuels in most cases. I say in most cases, because some owners may have some pretty low octane regular in their given area. The KLX250/300 has an 11:1 compression ratio. With a well designed 4-valve head like the KLX has, and 11:1 ratio, 85-87 regular unleaded should usually run OK without damaging detonation depending on altitude. The BB351 kit has a 12:1 compression ratio, and I don't know if this too much for regular gas. However, I asked Bill Blue specifically this question, and he responded that he frequently ran unleaded regular in his 351/pumper carb setup and had no detonation. Of course, being that the KLX has a manual transmission, a rider can just about intentionally cause detonation by lugging the engine at super low RPM under load, but I don't think that's what we're talking about here. My '06 has an OEM 300 kit with 11:1 compression, and it will run on regular.

I still contend that the clacking that many hear on their KLX's is from the cam chain.

 

When I first started riding the GF's 250sf I kept hearing a rattling at low RPM takeoff. Finaly figured out that it was the whaletail/rear fender assy. I could reach back with the left hand and dampen out the vibrations to get no noise. I doubt this is what most are hearing but I thought I would throw it out there.

 

Hi!
The bracket holding the license plate has a corner facing the exhaust. Remove the license plate, and the support bracket. Flip the bracket upside down and secure it in place. Remove the two side reflectors, and move them down to a larger slot. You'll need to add a washer behind the nuts. Re-install your plate and notice how we've cleared the exhaust exit. naaaa!!! Didn't work!
What did work was that the plastic guard fender which protects the single rear suspension coil, passes between the rear tire and the inside of the fork. The plastic guard begins to oscillate at initial power and slaps against the frame. Creating a loud rattle. I installed a thick sticky foam strip on the plastic guard to take up the space between it and the frame. Completely cleared up the rattle.