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Re: Engine shock absorber

The 2 lobe sprockets,cam and spring were introduced on later post war models...Springs for the 4 lobe set up were wound from flat wire and from round wire for the 2 lobe set up...The pressure exerted by the two spring types is quite different so parts should not be mixed...The spring nut also differs slightly...
The 4 lobe cams are quite pointed and do not move against each other readily when force is applied to them, so a lighter spring was used for these...The 2 lobe cam had far larger radii and was altered to smooth out the cam action...As a result the cams move against each other more easily, so a heavier spring was used for these to compensate for that...
As a point of interest there are two versions of the 4 lobe cam...Later 4 lobe cams had the width of the faces of the cams increased to reduce wear...

Engine sprocket carriers with the spacer machined as part of the carrier have the advantage that if the nut does come loose they are not subject to resulting wear as the whole carrier is hardened...If I make spacers up for the 'separate' spacer types I make them from silver steel and harden them....The main bearing spacer within the crank case is also better for being hardened IMO as that removes the potential for wear in the case of a loose nut...

When the 'one piece' sprocket carrier is fitted chain alignment is adjusted (if required) by the use of spacer shims..These are .005" and .010" thick....Part numbers for these shims are 66-1707 and 66-1708...Ian

email (option): ian@wright52.plus.com

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