detonation

Even with 93 octane fuel I can hear the ping of detonation when accelerating hard. Ive checked timing its fine and doesn't over advance. Is detonation caused by lean conditions when everything else seems ok. Motor is stock compression and has 24,000 miles but runs strong and has good compression. If not lean what could cause the ping ?

Which engine and what mods are you talking about.
Steve

I doubt very seriously if your engine is going into detonation.... a diesel engine runs on detonation.
Detonation means more like the fuel mixture charge fires off all by itself by high pressure and internal heat....with no electrical ignition system... such as spark plugs. Or the fuel "explodes" uncontrollably right after the plug ignites the mixture.
If you hear anything that makes you think of detonation in a stock engine, especially at less then 9.5:1 compression ratios.... I can almost guarantee it is preignition or maybe a mechanical noise like valve train or piston slap... etc.
If your timing is correct and you're using the right grade fuel... 87-91 octane, a common issue with old engines is preignition due to a lean mixture at WOT and carbon glowing white hot in the combustion chamber or piston crown or even the tip of the spark plug elements glowing white hot.
That can lead to preignition.

Your engines combustion chamber could be coked up, there by raising the compression too high for the fuel you are using. Try upping the octane and or change gas stations. Your ignition could be advancing too early, 30 + year old springs will do that. Detonation occurs after the spark plug fires and pre-ignition occurs before the plug fires. Different causes, different sounds, both bad for the engine.

How has nobody mentioned Seafoam yet?

These days you can buy a USB borescope camera for under $20, with it you can see clearly just how much carbon is on your pistons. Although Seafoam and the like won't really get a combustion chamber "clean", they (and pretty much anything, including water, carefully injected into the intake) can knock off the big flakes of carbon that tend to glow and cause preignition.

Maybe try giving it a couple of degrees less ignition advance?

The 550's can be bad for that, if using slide carbs and you gas it at low rpms. The 1100 have a lower CR form the 10:1 on the GPz550.

Pinking and detonation can be engine wreckers, I recently took a piston out on my 550...

I think the deal with CV carbs is you can wind it to the stop and the engine will only take what it wants, as opposed to slide carbs. Controversially, I quite like Cv carbs for road use.

I think they're right, carbon build up.
Steve

Very lean fuel mixtures will cause detonation. Richen the part of the throttle where the knock is evident.