Whats the best ratio???

[davo5791]

Ive got a Zongshen 140cc engine, i was just wondering if anyone would know what the best fuel to air ratio is???

 

[sean01]

is what way mate... how are you measuring it?

 

[dadof2]

to answer this we would have to know so many factors i cant think of them all like air temp ,density can i ask why do you want to know
like as in are you trying to tune youre bike

 

[westy465]

stochiometric ratio. 14.7:1

 

[sean01]

high 12's is wat most people aim at.

but i still dont think this is his question

as he'd need it on a dyno or at least have an AFR guage

 

[davo5791]

fuel to air ratio on my carby???

 

[sean01]

yeah mate your still not being specific enough..

are you simply talking about how many turns your mixture screw needs to be or do you have some way of measuring the ratio out of the exhaust?

if its the mixture screw setting then that comes down to a proper carb tune to get the mixture screw @ or about 1.5 turns from closed...
but its not as simple as just screwing it to 1.5 and leaving it, you must have the correct pilot jet installed so the carby/engines likes that setting..

if its the AIR FUEL RATIO as measured on a dyno then this has already been answered..
12.5 - 13.5 is considered a perfect ratio

now please re-ask your question again with all the needed information that will help us help you..
cause at the moment this is going no where as you havent even told us what carby you have or or even what your trying to do

 

[davo5791]

Well i had a lifan 140cc and the carby was set up really nice for it. I havent changed anything on the carby, i was just wondering if it should be changed or not.

 

[dadof2]

how is it running as in
bogging down ,pinging or exhuast glowing missing at anywhere in the rev range wont idle clean

 

[fane]

what they are saying davo is that there isnt an electronic keypad on the side of your carby that you dial in the ideal AFR into - neither is there an easy way measure the AFR without proper equipment

you'll find that no one really uses AFRs to talk about the tune they have on their bike they talk in screw turns from being all the way screwed in for example mine is 1.5turns out