LTGTR
XS650 Addict
Im having a friendly dissagreement/discussion about the way the mixture screw works on our BS38 Carbs.
My friend says the early BS38's (he means up to TX) have a mixture screw that richens the mixture when you turn it out, and on later models (my 77D) it works the opposite i.e. it leans the mixture if you turn the screw out.
From my learning on this forum I beleive the mixture screw works the same on all BS38's i.e. you richen the mixture if you turn the screw out. I remember 5twins/Jim or Gary describing the mixture screw as a "real mixture screw" because what arrives, and is metered by the screw, is really a mixture of air and petrol and turning the screw out allows more mixture in.
My understanding is because the mixture screw is on the engine side of the throttle valve then its a mixture (or fuel) screw - on the air cleaner side of the throttle valve its an air screw. Did the design of the BS38's change over the models.
My friend did explain his opinion to me - he says its because of the different way the air mixes with the petrol in the bowl - early design the air mixes via the holes in the pilot jet - later models the air mixes with the petrol as it exits the top of the pilot jet.
Can somebody clarify this please,
Thanks Ray.
My friend says the early BS38's (he means up to TX) have a mixture screw that richens the mixture when you turn it out, and on later models (my 77D) it works the opposite i.e. it leans the mixture if you turn the screw out.
From my learning on this forum I beleive the mixture screw works the same on all BS38's i.e. you richen the mixture if you turn the screw out. I remember 5twins/Jim or Gary describing the mixture screw as a "real mixture screw" because what arrives, and is metered by the screw, is really a mixture of air and petrol and turning the screw out allows more mixture in.
My understanding is because the mixture screw is on the engine side of the throttle valve then its a mixture (or fuel) screw - on the air cleaner side of the throttle valve its an air screw. Did the design of the BS38's change over the models.
My friend did explain his opinion to me - he says its because of the different way the air mixes with the petrol in the bowl - early design the air mixes via the holes in the pilot jet - later models the air mixes with the petrol as it exits the top of the pilot jet.
Can somebody clarify this please,
Thanks Ray.