Fuel Consumption

[JimKamenidis]

I've recently changed to a NGK spark plug and I did some plug chops.
I finally decided that it was too rich at idle so I lowered the needle the full two notches. Now I think it is running pretty great and idles with idle screw not as far in as when it was rich.
My main question is do leaner mixtures consume more fuel than richer ones because I think I have noticed a difference.?
My other question is don't leaner mixtures rev higher? Doesn't that mean an increase in speed??

 

[JimKamenidis]

thanks really!!

 

[HseLoMein]

to answer both your questions, No and Yes

A rich mixture ill consume more gas than a lean mixture. Rich = More gas less air, Lean = More air less gas

and Yes a leaner mixture will rev higher than a rich mixture, Yes you do get more power.

 

[JimKamenidis]

thank you very much!
have you ever tried 100 octane fuel??

 

[motorpsycho]

don't forget that with a leaner mixture you will get more power, but you risk melting the piston (if it's too lean).
you may also experience a bog at wide open throttle if it's too lean, and your engine will run hotter.
100 octane fuel is a waste of money because the compression ratio on these engines is too low.
you will get best results using 87 octane fuel, and you will save a little money.
using high octane fuel in one of these engines is the same as throwing money away.

 

[JimKamenidis]

I guess you're right..
thanks for responding

 

[dmfelicia]

I guess you're right..
thanks for responding

yup.

 

[HeadSmess]

i love all the blab about hi octane fuel

the reality is... the higher the octane....the SLOWER it burns!

it doesnt "explode" so easily when compressed... the flame travels slower...more time to burn completely...

so in a low compression 2 stroke, its only partially combusted by the time the exhaust port opens. wasting it...

lo octane, on the other hand, wants to explode.

faster flame front, more burn, more energy released, more power

UNTIL you

A; add a GOOD pipe.

a well designed pipe can increase a STATIC compression ratio of say, 8:1, all the way up to 16:1 or more (a diesel is this high. and they dont need a spark to light their fuel!) whilst running in "the band"
hi performance 2 strokes require hi octanes.

B; shave the head/cylinder.

increase the static comp ratio. but may be too much, if you fit a pipe...


just like lowering comp ratios in turbo/supercharged cars