Kickstart loose

I have just had the same problem on my Velo. It had a 3/8 unf bolt in it - however the female thread was cycle. So check the thread carefully, runa tap down it if it is chewed and then fit a correct length of bolt. Should solve your problem. It solved mine.

I have a folding KS on my 99 , I think the bolt is 3/8th UNF , its a bit short and a longer bolt would find the unused threads. Has anyone else had this problem and how did you sort it.

Yes Well UNF is being used by the after market people has the right thred 3/8th 26pti CYCLE thead are getting hard to find or expensive too buy,

OK so you have a folding kickstart. Is it an original or a recent after market one.

The original one for a Dommie would have had a BSCY (Cycle) thread and was probably 3/8 dia x 26TPI.

The 3/8 dia UNF is also 26 TPI but the thread form is different and so the two threads do not hold securely, or even safely. Some amateur engineering types will argue that the thread form makes no difference. They are wrong and should get re-qualified or stop claiming to have an engineering qualification.

The 3/8 x 26 TPI BSCY threads are readilyavailable and not particularly expensive.I can recommend you to Acme Stainless (they have a web site)who supply standard bolts and will actually make you over length bolts if you need them.

If you have an after market kick start which has been made using a 3/8 UNF thread then again these are easy to get. i get mine from my local screw stockist in both plated steel and stainless steel. After market manufacturers are really interested in profit, obviously, and so will opt to use a cheap alternative to the BSCY threaded components.

Incidentally if you need taps and dies for BSCY threads try Tracey Tools (again a website exists).

As for your final question about length, well the bolt either needs to finish at the face of the kick start casting so simply measure it and get a bolt of that length. Alternatively, add on some length to the same as the thickness of a nut so that the bolt protrudes and fit a nut as a locking mechanism. HTH.

Previously michael_jobson wrote:

OK so you have a folding kickstart. Is it an original or a recent after market one.

The original one for a Dommie would have had a BSCY (Cycle) thread and was probably 3/8 dia x 26TPI.

The 3/8 dia UNF is also 26 TPI but the thread form is different and so the two threads do not hold securely, or even safely. Some amateur engineering types will argue that the thread form makes no difference. They are wrong and should get re-qualified or stop claiming to have an engineering qualification.

The 3/8 x 26 TPI BSCY threads are readilyavailable and not particularly expensive.I can recommend you to Acme Stainless (they have a web site)who supply standard bolts and will actually make you over length bolts if you need them.

If you have an after market kick start which has been made using a 3/8 UNF thread then again these are easy to get. i get mine from my local screw stockist in both plated steel and stainless steel. After market manufacturers are really interested in profit, obviously, and so will opt to use a cheap alternative to the BSCY threaded components.

Incidentally if you need taps and dies for BSCY threads try Tracey Tools (again a website exists).

As for your final question about length, well the bolt either needs to finish at the face of the kick start casting so simply measure it and get a bolt of that length. Alternatively, add on some length to the same as the thickness of a nut so that the bolt protrudes and fit a nut as a locking mechanism. HTH.

3/8" unf does not have the same T.P.I. as 3/8" BSC which is 26 T.P.I.

3/8" UNF is 24 T.P.I.

Tapping out a UNF hole to BSC thread (or vice versa) will ruin the hole. I would try to find out what the original thread is in your kickstart by looking up the hole from the back, hopefully when it was manufactured the hole was tapped right though enableing you to see what it is.

Regards

Peter

I take your point about the thread pitch and should have checked it before I wrote. Apologies for the oversight and thanks Peter for correcting me.

However I am slightly bemused by your suggestion that Robert should peer up the backside of the threaded hole and that would enable him to determine the thread. LOL indeed. The easiest way is to take a known threaded bolt and try it in the threaded portion of the kick start. As you infer the 26 or 24 TPI will allow only one bolt to pass right through. Simples really.

I have had this problem on all the Nortons I have ever owned! They were all very second hand when I bought them. Once the KS come a little bit loose both the inner and outer splines wear quickly. There is however an easy and permanent repair! Clamp the KS in the vice across the bolt hole and put a hacksaw cut through the existing split in the kick starter. Find out what your bolt thread is and purchase or have made a high tensile bolt of at least 60 tons tensile. Bore a 5mm hole right through the length of the bolt. This will strengthen it and give you a hole to put the easy out into when/if you break it. Since doing this to my KS ers I have had no further trouble. Current bikes being 2 Atlases and a 500 inter.