classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: Kiwikeith on April 25, 2011, 02:08:50 AM
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I have just started work on my 1960 BSA C15, which has been sitting around not running for a good few years since the clutch apparently disintegrated.
Before starting to restore anything or hunt missing parts, I decided to check out the guts of it!
First concern is the big-end bearing of course. I do not know what it sounded like when it was running, so I started the dismantle. There is 1.5 to 2.0 mm (0.060 to 0.080") movement from side to side at the little-end. Does anyone know if that is going to work or is the big-end already at the end of it's life? I don't want dismantle the flywheel/crankshaft assembly or get it re-built if I don't really have to.
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What is important in big-ends is the up-and-down movement.
There should be none.
While that does sound like a bit of sideplay, if there is no metal in the sump or oil it should still be OK to use. Or thats what the manuals say, not knowing C15's or your engine personally..
P.S. it should also feel quite smooth when you turn it over, holding onto the top of the rod or the piston. Any roughness anywhere is not good...
Opethiselps.
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If it,s 1960 it possibly has a plain big end bush which is not good. If you want to make a good job of it I would remove the bush and fit the later needle roller type and it will last for ever. It,s false economy to build it all up only to find that the big is no good. All the best.
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Thanks guys. As it's not much of a bike yet, my first thought was exactly like yours R.
However, my natural instinct is to follow Goldy, but I have hesitation about parting the flywheels as the set-up instructions in my manual are a little vague & I do not have micrometers or vee-blocks, etc.
I saw a guy in Israel selling a complete big end assembly on e-Bay for $80, but could not be sure about the part number he had, and it could be even worse than mine!
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It,s not too difficult, the big end pin is "stepped" and so the flywheels are pressed on from both sides. To remove you need a small press and put a piece of steel plate between the flywheels so that one of them can be held whilst the pin is pressed out to one side. It,s easy to make a pair of vee blocks. Two pieces of 50 x 50mm angle with a vee cut into one leg then file them to a knife edge. Bolt them onto a base and you only need a dial indicator gauge. Go on have a go?
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I know, I know, I have looked at pictures in the manual.
Will need to get out the trusty arc welder & an old hydraulic jack to make a press!!!
I seem to spend more time making tools than taking it to pieces and at this rate I won't be riding for another couple of years!
Can you point me towards a source for the roller bearing?
Thanks again, Keith
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Alpha Bearings supplied them originally and still do today. http://www.alpha-bearings.co.uk/home.htm
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Wow! thanks.