03 KLX400 pinging

[uquackmeup]

I have an '03 KLX 400 with the 3" open air box mod, Dyno Jet/Moose needle at the 4th clip position, fuel screw open to 3 1/2 turns out, stock main and pilot jets, with an FMF exhaust. The bike pulls cleanly everywhere, the plug is tan, I feel no glitches other than the bike pings in 5th gear at partial throttle below approximately 5800 rpm. It will accellerate through this spot if I'm on the gas through the gears. Hi-test fuel around here is 93. I'm at sea level. Any jetting suggestions, or other suggestions besides race gas? I have a feeling knocking the timing back a couple of degrees would do the trick but I have no clue how to do that on this bike.

Thanks in advance,

Ron

[Wayward Son]

are you sure its pinging?sounds like your in to high of gear and your hearing the piston slap.

[uquackmeup]

!st, thanks for the response. I believe it's pinging as it sounds like bad static as opposed to any actual knocking. I guess my question would be what would be th lowest RPM to cruise in in 5th? This happens anywhere below 5.8k at partial throttle slow roll ons.

Ron

[Wayward Son]

what gearing?

[uquackmeup]

It currently has stock gearing for occassional freeway use. This bike is used as a canyon carver, and paved goat trail hauling. It's used as an alternative to a sport bike and is especially fun in the tight stuff but I have to be able to cruise at speed to get to my favorite roads.

[Wayward Son]

how fast in 5th gear when it makes the noise?

[uquackmeup]

This only happens at gradual roll on from partial throttle in 5th gear. I'm guessing that anywhere around 50 mph. Based on the tach, it's anywhere under 5.8K rpm's.

[uquackmeup]

I just got back from a ride. The rattle sound, which is closer to describing it, happens anywhere below 60 mph in top gear cruising speed. The mph is from my GPS, so it's more accurate than my speedo. The rpm's at 60 are right around 5800. I can't duplicate it in any other gear, or at least it's so minimal in other gears that I can't hear it.

Ron

[Wayward Son]

try disconnecting the tps and go ride.

[uquackmeup]

Unfortunately, no difference with the TPS unplugged.

[Wayward Son]

i dont think its detontion.your hearing the piston or drive chain rattle.maybe cam chain.

[uquackmeup]

I just bought this bike with only 900 miles on the clock and have only run 2 tanks of fuel through it. I'll try a new brand of gas tomorrow. I hate to think it's anything mechanical failing. The bike runs very well and I serviced it prior to riding it. I haven't seen any Mickey Mouse work by the prior owner yet, either. Thanks for all the help so far. I really thought the TPS might be the culprit as I went through a similar problem on my HD with adjusting the VOES.

Ron

[uquackmeup]

Just an update: I ran a tank of Chevron Super through it and even added some snake oil (NOS octane boost) with no difference. As a work around I upped the rear sprocket to a 47 which keeps me in the powerband a little better. I guess I can only use 5th as a high speed/freeway overdrive. I hate when things are not perfect, though. Sooner or later I will find a resolve.

Thanks again for all the help,

Ron