Bike started running wierd all of a sudden...

[Buzz Bomb]

I was playing around on my bike today, and all was fine. Then out of no where it started running strangely. The motor was pinging (this was still the same tank of gas that I used when starting the bike and it ran fine). I drained this gas and got new gas, but the bike runs the same. Does being too rich make the bike pop or knock when the engine decelerates? It's pretty humid outside today and the bike seems to be loading up. I'm lost, as the bike has run fine all summer. I have a clean filter and all... Any ideas? I'm running 420 main, S-7 nozzle, stock needle in 2nd clip from top, and 2 turns out on air screw. Oh yeah, and a 25 pilot. (2001 CR250)

 

[Buzz Bomb]

Oh yeah, I repacked the silencer the day before. Could incorrectly packing the silencer make the bike run funky? I mean like too much or too little packing? It may have been on the tight side.

 

[dell30rb]

I dont think the packing should make that much of a difference.

I'll bet that your carb has got some gunk or water in the float bowl that is messing with the jets.

 

[Buzz Bomb]

Nah, that's clean man.

 

[MXP1MP]

What does the plug look like? Does it do it at all or only certain throttle settings? Is it hard to start at all? Do some runs and plug readings if that checks out okay might want to check for air leaks next. Pull the plug cap and make sure its clean and check the kill switch maybe its grounding out on the handlebar but I doubt it. I really doubt over packing the silencer would cause it besides it doesn't sound like you really over packed it.

 

[Buzz Bomb]

It's definately rich now that I think about it. Yesterday was blistering hot and very humid. The pinging is occurring after I blip the throttle and let off. I also fouled the plug later yesterday. The plug was wet fouled.

 

[Rockey5000]

I had the exact same problem with pinging, but the jetting was spot on and all of a sudden the bike started pinging. It turned out to be a shot wristpin bearing. The extra play in the bearing caused the piston to have the ability to move up even farther in its stroke creating more compression and causing the pinging. I replaced the top end and the bike ran fine. How long do you have on your top end?

 

[Buzz Bomb]

Only about 20 or 30 hours. I don't know how it could be worn out this early because I haven't ridden a whole lot this summer.

 

[GMX]

My freind had the same problem on his mini(kx80) and we ripped the carb out and he forgot to fully tighten one of his jets and it was running like ****