r65 carb settings

[jimborbm65]

Hi all ,
I have a 1979 r65 with 29k on the clock . The manual says half a turn out for the slow run mixture screw .
I have always only achieved good running with one and a half turns out on both carbs . This I understand is a fuel quantity screw not an air quantity .I have just refurbished both carbs with new seals , jets and gaskets but still only get good slow running with one and a half turns out. There are no inlet port air leaks .
Do I live with it or look for some fault ?and where does the slow running air supply come from ?

Thanks all JIM

[Rev Light]

I though it was 2 turns out. However I have not got my manual handy. Half a turn seems too little.

[barryh]

1/2 turn out is normal 3/4 at most although I did hear recently of one R65 needing more than 3/4.

Is it possible a smaller pilot jet has been fitted than the stock 45 ?

It is a mixture screw and meters fuel although to be precise it meters a pre-mix of fuel and air which is then further mixed with the small amount of air coming under the throttle plate at idle. The pre-mix air comes from an idle air inlet jet (just a hole which is not replaceable) at the carb inlet and a cross duct which provides air to the pilot jet emulsion holes so that it mixes with the fuel passing through the pilot jet.

[SteveD]

Anything's possible on these aging bikes as P.O.'s have done all sorts of unknown things to them.

The BING manual confirms the 0.5 turn on the mixture screw, and the 45 idle jets, but I see the 325-326 carbs had 40 idle jets. Other R65's with different carb numbers had the 45's.

[vanzen]

Agree with the above advice.
The manual specified 0.5 turns out will be a preliminary setting only.
With the screw set to that position, the engine should start and idle –
a place to begin with tuning.
A significant deviation from the preliminary tuning position, however,
may indicate an idle jet that is incorrectly sized, dirty, carved out by improper cleaning, etc. ...
or carb body passages suffering from these same afflictions.
Also, as engines grow old and tired, their optimum fuel needs may change.