carb spacer

[1608]

I'm fitting a new carb to my 1960 G12 and thinking of using a thin paper gasket and sealant in place of the 'O' ring as I believe the ring encourages constant checking and over tightening.I am reliably informed that the carb body material 'mazak' suffers from what is commonly known as 'creep' ( distortion ). As I believe the ring also acts as a heat barrier I want to use a fibre type spacer.
Looking at the photos many, in fact most, of the singles are fitted with a carb spacer, as is my own 18s, but hardly any twins.
Any wise words of advice most welcome.
I'm not given to over tightening bolts/fitments etc, but am afraid of spoiling a new carb.
Old carb is distorted and causing weak mixture cos' of worn slide, new slide wouldn't even look at it!Edited by - 1608 on 04 Aug 2010 3:18:41 PM

[dave16mct]

You will find that your new monobloc comes with a very thin O ring which won't distort your carb like on the old monoblocs. Use a short spanner and only just nip it up. A smear of silicone will hold the thin O ring in place. The twins do have a thin heat spacer.

[1608]

Thanks Dave, very to the point. The thin 'o' does make sense.

[petert120r]

When I fitted new Concentrics to my Bonnie Surrey Cycles advised me not to bother with paper gaskets as a new rubber ring is sufficient sealant. That was 1000 miles ago and no problems.

The fibre spacer acts as the heat insulator and is specified on twins. I've used 1/8" or 1/16" thicknesses depending on the model plus an "o" ring on the carb flange. Use the paper gasket between the manifold and spacer. I've never had to use additional sealant.

As you suggest the main thing is to avoid overtightening the screws to avoid flange distortion. I was taught to do them up hand tight and then one turn only.

[1608]

Great! hope new one arrives in time for IOM, or its back to the old one which I haven't been very kind to!!