What is a ping ?

Hey guys, I am experiencing a ping or bing or what ever you want to call it.
No really , just what exactly is a ping ?
Are there different kinds of pings ?
What is the damage a ping can offer one ?

Here is my gremlin, explained.
Start the bike and ride in first gear to warm up slowly, no ping sounds normal.
After bike is warm 5 minutes or so here it comes, ride bike in first or second gear around yard and as you let off throttle to make a turn there is a very distinctive ping and it surges a little forward.

What do you think and where should I start ?

Pinging is usually detonation and require more octane in your fuel. If you are getting this using 93 octane unleaded blend fuel with race gas 50/50. If you are using lower octane like 87 or 89, try with 93 octane and I would suggest Shell or Mobil.

With the symptoms you listed I would also do a leakdown as it may be an airleak.

Check your intake manifold for cracks and do the leakdown for the rest

My idea of ping is under load the fuel mixture does not go off as desired. Instead of starting with a kernel of flame at the spark plug and spreading out to burn all of the charge some portion goes off by some other process. Increasing ocatne generally cures this. I had ping back in the days of automobiles with points and centrifugal and vacuum advance. You loosen the bolt at the bottom of the distributor and rotate it so it stops, I never bought more expensive gasoline.

On some bikes chain slap can be identified as ping. Not these for me, I never had ping issues at least that I recall on these bikes.

What you describe seems more of a jetting phenomenon. Four stroking is a term often used when it doesn't fire every time. I don't feel that what you describe at idle speeds will pose a damage issue. I have not worried about the strange things that happen going down hill with no throttle. Some of it may be along the lines of the activated radical combustion Honda experimented with and never brought to market.

Don't mix up ping with fin ring. The pipe can ping at times too.

I use high test gas in everything. Maybe rejetting is needed.

+1. I had a ping in one of my Trials bikes when it got hot. Lots of stopping and waiting at sections. Switched to Cam2 50/50 with 93 Sunoco and it was gone.

Ok, I will start with better gas as soon as I can. I have read about the down hill ping thing but don't have to many hills around here.
I will start with the 93 and go up from there.
I did not know if I was doing any damage by going the trial and error route.
Thanks guys.

In order to improve efficiency, the spark is advanced or fired during the upstroke of the piston. If the advance is too soon or if your fuel burns too fast (low octane fuel burns faster), then the fuel will be too far into it's burn before your piston ever reaches the top of the cylinder. Hot spots on the piston can also self ignite fuel prior to spark ignition or self ignite on two surfaces, compressing the fuel in between causing a detonation as well. Raising your octane level with better fuel or adding a fuel additive will help eliminate the problem.

Also check around your base gasket, if it is leaking, the fuel mixture could be leaned. Adding a thicker base gasket will reduce your final compression, also eliminating a detonation issue.

Sounds like you are on to something there ,
Base gasket is new
intake is new
But I will check, what is the best product to spray around those areas for leaks ?

Quick starting fluid

Sounds like you are experiencing "four-stroking" not pinging. The key word you said is "surge". Mine did that when it was too rich at the pilot jet. Ran great otherwise. Has anyone else felt this surging while decelerating or low rpms?

kinda a bitch to start when its cold to and you have to have the throttle cracked open a little to start.
I usually run the bike just a little after I turn the gas off and it gets louder then not so much of a surge then tho ?

"four stroking" doesnt cause a surge, or cause anything when the throttle is closed. four stroking is simply when the bike fires every 4 turns of the crank, instead of just 2. this is usually caused by a rich condition. when the bike runs rough because of too large of a main jet, and cant reach the intended rpm, four stroking will result. the roughness you feel from being rich is usually "four stroking".

Ok, just rode it tonight. I have been starting it rufo style, and it works pretty good. It only likes to start with throttle open even warm.
I tried to video it but you can't even hear it in the video. It only does it when you gas it in gear and let off and let the rpm's die down to go into a corner or just coast. It's really not surging like I thought it was , sounds more like a purng instead of a ping tho. I will try the higher gas tomorrow.

what bike is this on?

the 79 wr 250

so what does it do exactly when the you let off the gas?

The motor whines down for a second or two and then there is a nice distinctive ping , just one nice big one . throttle is closed at this time, just coasting .

and when it does this the bike lurches forward? they all do this do a certain extent, just not real forceful. i would venture to say it may be jetting related, or perhaps float height setting. would explain always having to open throttle to start. i doubt this is an octane problem. pinging would be a spark knock under load at larger throttle openings, not with the throttle closed.

on a 250 this should not really be felt much tho. those old motoplats do have alot of inertia but i wonder if that would almost minimize this instead of amplify it. the big 500 will pop occasionally and kind of shoot you a foot sometimes. i know ive felt that. have you set the timing with a dial indicator? or at least know right where its at?

Found some cool stuff on the web tonight , although I am not sure this is my problem but could be seeing how mine only does this when its nice and warm. So here goes I hope this don't open a can of worms, lol
Detonation , knocking, and pinging is caused by heat of compression in the cylinder and when left over un burned fuel air mixtures ignite by themselves from the heat (not your spark plug) this is called auto ignition and this causes the sound we here.

Octane rating is the measurement of the gasolines ability to resist auto ignition and basically the higher the octane rating the greater the gasolines ability to resist detonation , knocking or pinging . So the hotter your cylinder is firing the closer you are to auto ignition, like from over boring a cylinder to create more compression which means more air to squeeze into a tight spot which makes more heat.
Options are add a higher octane rated fuel or you could also retard the timing some because your already loosing power.

This is just what I have found and I am relaying the info for others to read and maybe they wont start a thread and then answer it themselves like I did after doing the research. lol
I will keep you informed on my progress