Gyrobob wrote on 02/09/13 at 11:07:01:Max cylinder temp happens with a perfect stoichiometric ratio, approx 14.7:1. If you are rich (maybe 12:1) or lean (maybe 16:1) of that point, the cylinder temp goes down.
The danger from lean mixtures is from detonation, not heat. Lean temps can burn unevenly, or even too rapidly which can lead to detonation, even though the temps are not as high as with a 14.7:1 ratio.
Lean temps can burn unevenly, or even too rapidly which can lead to detonation.
Im thinking Bob meant to say Lean Mixtures can burn unevenly blahdeblaaahblaah & so on,,
Im gonna step out on a limb here & TRy to explain the part about detonation. Im just takin a shot at it, based on my understanding of how an engine is built & what happens & when in the power cycle.
While the piston is coming up on compression the air in the cylinder get hotter, Boyles Law, IIRC, Halve the volume doubles the pressure & temperature. Compress stuff 9 to 1? Shazzam,, gets Hot, grab the line coming outta the compressor head,,
Anyway, if the fuel gets hot enough to catch on fire before the spark plug fires, thats detonation. If its doing that while the piston is still headed up, then thats pounding the POO outta bearings at the very least. What other damage mite it cause? I Dunno,, Thats just MY imagination at work there.
What does it matter that flame front propagation is uneven? I can see it affecting power, but I dont see it hurting equipment. Bob may well correct me on that.
I hope others will explain further the problems detonation can cause.
Exhaust gurgle,, its worth buying a bike just to hear it.