Magneto shaft taper.

Can anyone supply details of the standard taper fitting on magneto drive
shafts so that I can have a sprocket bored to suit?
Thanks.
Reply to
Nick Highfield
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Which one? there are three 'standards' listed in the Wipac Master Service Book.
Kind regards,
Peter
Peter Forbes Prepair Ltd Luton, UK email: snipped-for-privacy@easynet.co.uk home: snipped-for-privacy@easynet.co.uk
Reply to
Prepair Ltd
I think its the besa 'K' taper. Mag is a BTH MH1, similar to Lucas N1.
Reply to
Nick Highfield
After a quick measure with the verynears:-
Taper starts at 13mm dia and reduces to just under 11mm over a lenght of 12mm. Is that the 'K'?
Reply to
Nick Highfield
OK, I'll get the info out of the book later when we get home.
Kind regards,
Peter
Peter Forbes Prepair Ltd Luton, UK email: snipped-for-privacy@easynet.co.uk home: snipped-for-privacy@easynet.co.uk
Reply to
Prepair Ltd
Thanks Peter, that is the 'K' then. Just found out that commercial div'n of the company I work for sells sprockets (thought we only did plate wheels ie no boss) so I'll have a look at the catalogue and see if there is anything with enough meat in it to machine up.
Reply to
Nick Highfield
The sizes are as follows:
Small (Type M) 0.450" 29/64" -- 29/64" -- 0.359" 23/64" Medium (Type K) 0.519" 33/64" -- 29/64" -- 0.428" 27/64" Large (Type E & G) 0.591" 19/32" -- 19/32" -- 0.472" 15/32"
First dimension (decimal+fraction) is the largest diameter at the start of the taper Second (middle) dimension is the length of the taper Third dimension (decimal+fraction) is the smallest diameter at the finish of the taper.
The decimal and its nearest fractional dimensions are as given in the table.
Peter -- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:
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Reply to
Peter A Forbes
They also have a page of taper adapter units, 10 different types: I presume for adapting parallel shafts to taper key/drive.
Peter -- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:
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Reply to
Peter A Forbes
On a slight tangent ... but possibly helpful to someone in trouble.
I raced 250cc karts for years. Never had much money, so was adept at racing Sunday, rebuilding Monday in the local evening classes where we had the run of a school workshop.
One common problem was magneto flywheel coming loose on shaft. Eventually chewed up crank horribly. Far too much money to replace, so ground down damage so that magneto flywheel could be refitted. Filled the (severe) craters in the surface with a mixture of Araldite & metal filings.
Amazing. Lasted a couple of years until I went to twins, revved to 8k, did many races - all without any problem.
Horrible bodge to some, but would last for ever at our less demanding mechanical stress levels!
Colin
Reply to
Colin Osborne
Found following on Dave McCreath's site:-
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easy to read the dims but 1 in 5 taper is the important bit!
Reply to
Nick Highfield
"Colin Osborne" said
Far too much money to replace, so ground down damage so that magneto flywheel could be refitted. Filled the (severe) craters in the surface with
One man's bodge is another's ingenious repair ;o))
When I had the bike shop, a customer with no money at all came in with his mid seventies Honda 400/4 (lovely bikes!). He'd let it run out of oil and a big end was rattling. I felt sorry for him, it was a quiet week, so he did slave time for me doing stuff and I watched over his taking the thing to bits.
Amazingly, there was little sign of damage, the camshaft was OK but number three b/e journal had picked up and the shell had rotated in the eye of the rod. On the basis that I did it for nothing and, if it didn't work, I was to be held blameless, I filed the picked up steel off the journal and (yes, I did use a micrometer!) managed to get it pretty well round whilst maintaining size. There were horrid lumps missing out of the surface and it still makes me shudder to think of it revolving at 10,000 RPM, but it was round and fairly smooth. The same treatment was applied to the rod eye and a pair of second hand shells were obtained from a scrapper. The assembled rod rotated smoothly enough with no up and down play although the side to side wobble was worse than the other three rods - but not by much.
Well, you can see what's coming I'm sure. It fired up straightaway and ran like a clock. As I said to him, if it last an hour it'll probably last a year and he rode it for at least another year without problems until he got a job in Oxford (70 miles one way) which he did as a commute for a month until he moved there. I heard no more of it but I still wonder what became of it.
Regards,
Kim Siddorn
Reply to
J K Siddorn

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