Re: BING balance via manometer.
Posted: Sat Dec 22, 2012 9:35 am
Um , as Berryh has pointed out in his post and Bing confirm, the whole point in tuning carbs is to get them as lean as the machine will tolerate, anything else is a waste of fuel.
Phil Irving covers the subject well in his book Tuning for Speed , which at one time was considered essential reading for anyone who intended dabling with a motorcycle.
Maintaining a sufficiently rich mixture in transition is the determinant to how lean you can go , as confirmed by Bing.
The weakest mixture the machine will run cleanly on is the one which makes most power, so the statement that a Colortune sets the mixture too lean for maximum power is, err, stuff and nonsense.
There is no problem with combustion on any of my airheads, the mixture is a uniform colour throughout, so I don't know where the claims that the mixture is too uneven to get an accurate read from a Colortune come from - probably from someone who has never used one.
When tuning the mixture in transition on a well designed CV carb like a SU, apart from picking the right needle from the 600 odd SU supply, careful selection of one of the many piston return springs which SU offer is the secret to success.
Bing offer two springs. The latter spring is much the stronger and will enable you to set the steady rate mixture lean for maximum power and economy, while maintaining good drive-ability in transition.
Set up this way my 1000cc 37/11 G/S will do over 600 km before it needs around 30 litres sloshed in, and it is a real flier too, keeping up with my mates original old one owner Suzuki GSXR 750R , if I wring it's neck!
FWIW my 1600 cc car which has fuel injection which leans the mixture right off when cruising also does 600 kn from 30 litres ,at a steady 110 km/hr , so there is probably a bit more to come with the bike.
But only if I could find a couple of good MC type SUs ( or commission a batch of 100)- these Bings are a crude and inefficient copy of a Stromberg, which was a crude and inefficient copy of a SU !
Phil Irving covers the subject well in his book Tuning for Speed , which at one time was considered essential reading for anyone who intended dabling with a motorcycle.
Maintaining a sufficiently rich mixture in transition is the determinant to how lean you can go , as confirmed by Bing.
The weakest mixture the machine will run cleanly on is the one which makes most power, so the statement that a Colortune sets the mixture too lean for maximum power is, err, stuff and nonsense.
There is no problem with combustion on any of my airheads, the mixture is a uniform colour throughout, so I don't know where the claims that the mixture is too uneven to get an accurate read from a Colortune come from - probably from someone who has never used one.
When tuning the mixture in transition on a well designed CV carb like a SU, apart from picking the right needle from the 600 odd SU supply, careful selection of one of the many piston return springs which SU offer is the secret to success.
Bing offer two springs. The latter spring is much the stronger and will enable you to set the steady rate mixture lean for maximum power and economy, while maintaining good drive-ability in transition.
Set up this way my 1000cc 37/11 G/S will do over 600 km before it needs around 30 litres sloshed in, and it is a real flier too, keeping up with my mates original old one owner Suzuki GSXR 750R , if I wring it's neck!
FWIW my 1600 cc car which has fuel injection which leans the mixture right off when cruising also does 600 kn from 30 litres ,at a steady 110 km/hr , so there is probably a bit more to come with the bike.
But only if I could find a couple of good MC type SUs ( or commission a batch of 100)- these Bings are a crude and inefficient copy of a Stromberg, which was a crude and inefficient copy of a SU !
