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Michael Anderson
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30 May 2002 04:12 I'm looking for a source for shims and bearings for the cam box as fitted to a 1961 500 Manx. I've been advised that C3 bearings are appropriate. Are these specific to the Manx, or will any comparable industrial bearings work? Any comments or suggestions would be appreciated.
 
Ken McIntosh
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09 August 2002 11:40 Manx Float chamber height
To check the float height on any Amal racing carburettor it is worth making up a tool using a spare main jet cap nut.

This enables you to check without upsetting the 'in use' position of the floatbowl. Solder a 1/8" diameter x 1/2" long copper tube into the base, after drilling a hole to suit.

Push on a piece of clear plastic tube about 10" long, and hold it beside the hex cap found on the side all GP carbs.

Set the level to the bottom of the inscribed circle. Make sure the bike is level. Re-check several times, by turning off the fuel and draining the tube into a suitable container. You can do small rechecks by lowering the tube by an inch or so, and watching the level reset.

If the level 'creeps' at all, suspect the float chamber is not working correctly. You should be able to leave the fuel turned on for 10 minutes without flooding.

Over the years I have used all the types of Amal floatbowls, and have found they will all work well, if in good condition! The matchbox type is not suitable for methanol fuel. I have found little advantage in changing the level from standard. This normally only masks some other problem.


 
Rowan Bond
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26 July 2002 11:37 Cannot remember if I replied to this before but I found out that C3 refers to the clearance in the bearing from the factory. I restored an Adler years ago using standard FAG roller main bearings. Within a short period of time I found the motor tightened when hot. Having pulled the engine apart I noted signs of overheating of the mains. FAG were kind enough to test them and declared that I should have used C3 clearance bearings which were 30 micron looser (clearance between inner and outer track and rollers. The local bearing place actually supplied the new ones free of charge, which were fitted and I have had no trouble since.
So to answer your question, in my (admittedly limited) experience C3 bearings are specified for a particular reason and should be used if available. Obviously the bearings are the same size ie fit on the shaft and in the casing, but the C3 refers to the above clearance. My roller bearings were the stamped the same size, but after the size, C3 was stamped after the part number. Hope this helps

Rowan
 

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