My 99 has a folding KS bought 15/20 years ago, probably SS or Atlas. . The Bolt is too short and only uses half the threads and is losing the plot, ideally it should be long enough to fit a slim locknut on the outside and a washer under the head and nut, it also does not need half its thread which just damages the box splines . should be waisted like a big end bolt. It also needs to be high tensile steel ,with a nice plated finish and no numbering on the head. If only. I can see I'm going to have to compromise, I think its likely to be BSF or UNF probably going to have to get one of each ,any ideas where?. Probably going to have to modify a hex head set screw.
That bolt is 3/8 x 20 x 1…
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The 11/2 bolt as usually s…
The 11/2 bolt as usually supplied leaves about 6mm of thread unused in the lever and no spare for washers. It also has thread in the spline area where it can do no good at all only damage the spline. A total bodge. If I am going to improve this area then I want it all. Full thread engagement in the kickstart plus a bit of spare on the outside for a locknut and washers both sides. Does not seem too much to ask ,a bit of thoughtfull design.Should have been done in the first place.
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15/20 years late?! Anyway,…
15/20 years late?! Anyway, the thread, and bolt shaft should not touch the splines. The most common fault, with the kick start clamping bolt, is the thread running out before the clamp is fully tightened (probably due to the wrong bolt being fitted, in the distant past). A Spanish friend had this problem with a restored model 50. A washer, under the bolt head, enabled the clamp to be fully tightened.
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Mine came Direct from our…
Mine came Direct from our Norton spares expert with bolt. The washer would have been good if supplied and did not reduce the already skimpy thread engagement. The orriginal (made by Shelley for Norton) fixed arm KS from the 1960 99 is still giving sterling service on the Atlas , It has outlived the modern replacement and although scruffy is the only one seemingly able to stand up to the job of starting a HC Atlas. A compression plate is waiting in the wings.
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As John says - the 'threa…
As John says - the 'thread in spline area' isn't an issue since the shaft has a groove to allow the shank of the bolt to avoid the splines completely.
A big issue is that any wear (or poor tolerance in manufacture) in the starter lever splines slackens the fit. Then when the bolt is tightened, the splines immediately either side of the slot go into contact first and prevent the lever from drawing up tight all round the splines. Then the lever wobbles and wears no matter how tightly it is clamped.
Looking at some old levers, I see that some owners seem to remove the splines each side of the slot within the kick starter for up to about one third of the circumferenceso as to give the lever a better chance of being pulled snug and fitting all the way round. But then obviously fewer splines carry the load.
Spline joints are horrible anyway. My old (car) wire wheel splines were eventually so worn that the rear wheels would make a 'clonk' noise as drive was reversed from acceleration to braking.
And as Robert hints - the 1960'sengines with increasing size and compression ratios out-grew the old kickstart concept - not helped by having no decompressor. The Dommie Model 7 made sense as it was only like kick starting a 250cc. But with the Atlas and Commando, it's like starting a 375cc single. ButBritish 350 singles had decompressors - with lower compression ratios.
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That bolt is 3/8 x 20 x 1 1/2 inch and ithas part number 040102. I have also found that there threads are not enough threads and it does not clamp the kick starter to shaft to the axel very tightly. I was going to cut some more threads so it will clamp more tightly. Steve Surby at AMC Classic Spares sells a high tensile version of that bolt that is plated and has no numbers on the head of the bolt so I got some from him. He has a stall at Kempton Park. What you are looking for the above company sells.