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Re: Kick Start Return spring

Posted by hendred on Apr 02, 2021; 10:49am
URL: http://silk-motorcycles.221.s1.nabble.com/Kick-Start-Return-spring-tp5002147p5002154.html

One step forward, one back.  Have you tried reducing the spring pre-load by turning the housing back one third? I have just checked my kickstart and there isn't much spring tension when the crank is upright.  The greater the pre-load the more coil bound the spring will become on using the kickstart. With the kickstart mechanism off the bike does the crank move freely and return ok? A thought on the kickstart spring - if there are any sharp/rough edges on the spring it could bind when the spring is wound up.  
 
The Silk gearbox is based on the Velocette gearbox as used in Venoms, etc. laid on its side. If you don't have access to a Velocette manual there are several sources on the web such as this one

https://dunhackin.com/index.php/velocette-documents/mac-manuals/mac-service-guide-1965/118-the-gearbox

It is for the light weight MAC gearbox but the principals are the same, the main difference is the cam plate is at the front of the box and on a Venom it is at the back of the box (on a Silk it is at the top).  To remove the end cover take off the triangular plate in front of the kickstart crank housing and remove the circlip from the end of the mainshaft.  Then remove all the caphead screws round the edge of the cover.  The end cover should then pull off leaving the gears, etc. in place.  The two rods which the selector forks slide on may come out with the cover. Not a problem, just hold the selector forks in engagement with the camplate and slide the rods back in.  

The outboard end of the layshaft runs in a bearing in the kickstart mechanism gear.  The layshaft runs "backwards" and will try to turn the kickstart crank.  On early bikes the bearing is a bronze bush and on later ones a needle roller bearing.  Several of us have found the cage cracked on the needle roller bearing.  It is worth replacing it if you are in the gearbox.  The spec for the bearing is in the bearing list on the Technical Data / Downloads page.  They are readily available from Simply Bearings and are very cheap.  I use the best quality ones, the difference in price is minimal.

If you type "layshaft bearing" in the search box you should find several threads on gearbox and kickstart bearings
 
Hope this helps.