Pinging?

[mobrown]

What exactly is pinging? Is it kind of like the pre-ignition sound that cars can make if they have too low an octane or their timing is off?

I have a 91 CR250 that makes a sound when I'm really on it... usually at high speeds in the higher gears and when I'm on the throttle. I'm not sure if it is the infamous "pinging" or what but the bike has no loss of power. The sound however does bother me as I don't really know what the cause is. To me it kind of sounds like a ticking sound but at such a high frequency it almost sounds like... I actually don't know how to describe it but it may be what others are terming as "pinging".

Anyhoo... any suggestions as what to check, what to do, or how much I should worry about the sound? It does seem to be eminating from the cylinder somewhere but it's hard to tell because I have to be going faast to hear it and trying to tell exactly where it's coming from is difficult. I like things to be in good mechanical order so I would like to figure out what it is.

Thanks for any and all advice.

 

[gonzo843]

You should worry about pinging. It's bad for the piston. Pinging sounds like 2 pieces of plastic clicking and sort of grinding together. Might need to richen your jetting one tick.

 

[binthedirtnow]

I've been a little worried about pinging in my 2002 kx125 also, but I'm not sure what it would sound like in a two stroke. Sometimes I don't know if I'm hearing my FMF pipe ring-dinging or am I hearing pinging?? I haven't had the bike very long so I'm not sure. Is there another way to descibe the sound??
Thanks for the help in advance,
B.

 

[gonzo843]

Whenever you hear that sound, just richen the jetting up and see if it goes away.

 

[mobrown]

Richenening...

Gonzo thanks for the replies.

I'm pretty mechanically inclined but that does not include carbs. If I remember correctly the terms richen and lean are in reference to the amount of fuel relative to the amount of air... is that correct? So does that mean I need to have more fuel per the same amount of air (i.e. do not increase air flow only fuel)?

Is the needle the control for that or do other jets need to be adjusted? I would appreciate any further advice.

Thanks again.

 

[Chili]

Give this article a read to get the basics of carb tuning. http://www.ericgorr.com/techarticles/carbtuning.html

 

[binthedirtnow]

Again, could someone please offer some descriptions of what pinging sounds like in a 125 2-stroke?? Is it better to listen for it on any one side of the motor?? Will it be louder than the exhaust noise if I have a FMF Q-spark arrester silencer?? DO you think I will be able to hear it with the bike on the stand while I'm rapping the throttle open??
B.

 

[gonzo843]

Gonzo thanks for the replies.

I'm pretty mechanically inclined but that does not include carbs. If I remember correctly the terms richen and lean are in reference to the amount of fuel relative to the amount of air... is that correct? So does that mean I need to have more fuel per the same amount of air (i.e. do not increase air flow only fuel)?

Is the needle the control for that or do other jets need to be adjusted? I would appreciate any further advice.

Thanks again.

Well the carb is extremely easy to work on. The article on carb tuning is good. But if your riding wide open then change the main jet bigger. That's the big one hanging out of the float bowl when you pull the screw off, if your more mid throttle then you'll have to adjust the needle. That can be a pain with the spring. The best I can tell you is go at it and create your own way to put it back together. It's sort of tough but once you got a system down you can do it pretty quick.

How does the plug look?

 

[binthedirtnow]

Gonzo(or anyone else) I richened the jetting and the motor still sounds the same. Maybe it's not pinging, maybe it's just the sound of a crackling, snappy 2-stroke!! But, I would like anyon'es best description of pinging so when I hear it, I'll know what it is.
B.