what causes detonation?

NORTHMANSX

NORTHMANSX

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hi guys, this maybe a dumb question but i don't know myself.

what causes detonation?

what will it do to a piston?

what symptions would i look out for?

thanks for your input, just trying to figure it all out.
 
Detonation is when compression causes the fuel in the engine to combust before the top of the pistons stroke (also before the spark occurs). On most engines you can hear a knocking or pinging noise which is (from what I was told) the head actually coming off of the cylinder and then slamming back down due to the tension of the head bolts. Detonation can really do some serious damage to a piston and other engine components.
 
it could be from alot of carbon build up ....the carbon gets super heated and ignites the fuel before the spark plug has a chance to do its job. try running super unleaded,and, or retard your timing a little to stop this problem ....has the head been cut ?;):D
 
the noise is caused from the two flame fronts coliding. one flame front started from heat built up enough to ignight the fuel at the edge of the piston/head, the other from the spark plug, they travel twards each other kinda bang together..

this causes vibration to travel to all points lower, crank, connecting rod bearings and your piston. when the front comes to gether the explosion will sometimes take tiny amounts of material off the piston and eventually destroy it.
 
what you guys are explaining sounds to me like pre-ignition.. is there a diference??

in the thread started by DoktorC, entitled motor mystery.. would detonation cause that? that is exacally what my pto piston looks like. somebody mentioned to me that maybe detonation, or bad fuel or a bad crank seal. anybody know for sure what?

in my case i have the stock headgasket and never cut the heads. i am at a loss to expain it. anymore info would be greatly appreciated..
 
You are probably to lean . Possibly vacuum leak ,partly cloged Jet ,Jets to small ,carbon build up increasing compression .or timing to far advanced ,leaking around the air cleaner boots . There are lots of things that can cause it but one thing is for sure two strokes don't ping for long with out blowing a piston .
 
i have never heard any pinging, the timing is stock, jets are clean, i am only one size down from stock, but i will check my carb boots and crank seals. oh wel it's done and soon to be fixed.
 
There should be a post from a couple of years ago where we went all through pre-ignition, detonation, and much more including octane ratings, etc. I don't know if you can go back that far on here, because that history may be at the 'other' site, but it has all that you asked for and more. Sorry, but I'm too lazy to attempt repeating it all.
 
excellent reading....

from that article I need little more convincing that I won't be arbitrarily peeling layers from my head gaskets anytime soon.....

Stock Yamaha is performance enough for me...(someone who has little tuning experience)...

TJ
 
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