Quote:
Originally Posted by Bob KellyIII
I have been re-reading these posts and I see what you are saying Danno....
hotter air occupies more volume than cold air therefore the warmer it is the less air is in the cylinder.... meaning it would be richer ...your right !
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there's a problem with that theory though... Richer FAR will ignite well up into the 20:1 ratio's where as leaner FAR's only do down to about 15~16:1 max
what I'm experienceing is the cylinder cutting out entirely not blubbering
it's missing a beat or 3 and then hitting again meaning to me it is running lean in that area.... I guess the way to tell would be to pull the plugs and do a color check
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You're getting numbers mixed up. AFR = Air Fuel Ratio... Air is much larger component...
rich AFR = 14,0:1 to 10,0:1. That's 10 parts air to 1 part fuel, which is super rich factory mixtures.
stoich AFR = 14,7:1 meaning 14,7 parts air to 1 part fuel. Note that this is more air and less fuel than rich mixture
lean AFR = 15,0:1 to 20,0:1 for lots of air to 1 part fuel.
Lean mixtures still burns and bike feels lazy and weak. Rich mixtures causes cut-outs and stumbling. Don't bother reading plugs unless you put in brand-new plugs just before ride and chop throttle and turn off engine just at point you want to analyse mixtures. Even then, plug readings aren't that useful or indicative of mixtures with modern unleaded petrol. You won't be able to tell difference between rich 13,5:1 mixtures vs lean 15,5:1 mixtures. Maybe between 10,0:1 vs 16,5:1 which is HUGE range.
You need to be less haphazard about your mods. Take a more methodical scientific approach and write down your procedures and data.
1. record morning cold-start temp, 2 shims, how's it run?
2. record hotter afternoon air temp, 2 shims, how's it run?
3. record morning cold-start temp, 1 shim, how's it run?
4. record hotter afternoon air temp, 1 shim, how's it run?
5. record morning cold-start temp, 0 shim, how's it run?
6. record hotter afternoon air temp, 0 shim, how's it run?
