Quote:
Originally Posted by renault_megane_dci
Improving engine breathing is the way to go in my opinion.
If you have done a freewheeling setup, a more efficient "Pulse" will reduce their duration, could help with mileage.
If you can not P&G, improving engine breathing can only return gains if you can alter gear ratios (maybe with a set of heavier than standard weights in your CVT ?)
Taller gear ratios (through closer front pulley)s means for a given level of acceleration, your throttle body is opened more meaning less pumping losses.
Obviously, using more air means more fuel so it seems counter intuitive.
But it has been the recipe for eco tuning vehicles for long : tall gear ratios.
Maybe you can play with inlet temperatures to further save fuel (and maybe offset the need for tuning it richer)
If you are after money efficient modification, then you can never beat a free mod ...
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I have been doing lot of adjusting recently, roller weights, needle height and so on.
What I have managed to do is to get scooter run lot stronger, I needed to enrich mixture quite a bit when I removed intake restrictions.
Roller weights provide interesting results, running engine around 7000rpm seem to provide surprisingly better fuel economy than when running it 5500rpm, that is perhaps because there are long 4-7% climbs I need to climb and at 5500rpm engine just don't have the grunt and speed is nearly half in climbs than with 7000rpm, time spend on climb starts to affect fuel economy.
6500rpm might be sweet spot for climbing, so I try to get 7000rpm rollers weighted and order bit heavier ones.
I have gotten two tanks with 110 and 115mpg now with 7000rpm setup, unrestricted air intake and modified exhaust, also mixture adjusted to be bit rich.
Problem with freewheel now is that when I let go from throttle, engine cuts off because mixture is too rich to burn, with leaner needle position I had less of that problem.
Lean stumble is pretty much away now, occasionally there is tiny bit of it, but mostly mixture is quite rich, I think that tip of needle could be bit different shape for it to work better for low to 1/2 throttle as that tends to be rich, even idle mixture is set to compensate that low throttle a little. I could put one size larger main jet I guess, but current is quite perfect.
Brakes like to bind slightly, that is causing some fuel usage, for longer trips I usually push calipers a little that brakes unbind, I did try to make pistons move more freely, but it worked only for week, might need new calipers.
Not sure if I keep freewheel setup, it is very handy in city and at parking lots, also on some hills, but because of issue with throttle close and engine shutting off and my typical riding being on rural roads, it might not give much benefit, transmission oil change is soon, so I might try without it for a while.