Carb Adjustment

[socaljeff3798]

Hey guys I need your help. I have rebuilt the carb and it now starts and runs but off idle is it flat. but seems ok at the upper end.
My questions is when I disassymbled the card I counted turns on the Idle Mixture screws and the air by pass.
I had 5 turns out on the idle Mixture and about a half a turn on the air bypass.
Can anyone give me an idea of what they should be?

Thanks, Jeff

[ducapaso]

Manual says to close one of the air bypass and open the other to have a correct balance. in the 750paso FAQ topicthere's a post of mine with the complete carb balancing suggestions

Have a nice job, and

[higgy]

mixture screws if the jetting is proper and there are no blockages in the carb should be 1 to 1.5 turns,air bleeds one closed the other about .5 turns out, assuming you have them balanced as per the previous post

[socaljeff3798]

Thank you that helps a lot.
I am confused as this is just a 2 throat weber with one butterfly shaft opening both throats. I dont understand the balance part?

[higgy]

The air bleeds allow you to compensate for minute differences in the flow of air in each throat of the weber caused by very small differences in tolerences between the two throttle plates and chokes. You need a u-tube manometer to measure the difference in air flow between the two,which is why you only need to adjust one of the bypass air screws to compensate. when you measure this difference with the manometer you will see that one side(could be either of the two) will flow less than the other so you will need to allow more air to flow into the other sides bypass circuit to equalize the two to the same level of flow....balanced air flow for both sides of the carb
Hey just to add confusion to all this Adjusting your cam timing between cylinders is in fact accomplishing the exact same thing, balancing airflow into each cylinder

[socaljeff3798]

Ok, got it!....sorta! so the it is measured on the vacuum port on each throat?

[ducapaso]

under the throats, on the maifolds, plugged with a 5mm screw

[socaljeff3798]

Can I use 2 vacuum gauges to balance the air bleed on the carb?

[higgy]

Yeah you could,a utube manometer is simple to make and much easier to use. All you need is about 6 or 8 feet of tubing, something to mount it on and the adapters to tap into the manifolds

[ducapaso]

have a look at my gallery to see how I made it

[jayh]

Look on Ebay for 'Synchrometer' .Much easier than messing around with the other stuff,very accurate and will fit webers ,dellorto's as well as many other carbs for $30.00. Jay.