How do you check the primary gear bushes for wear? Do you measure the crank then measure the bushes or initially is it just by feel. To me it seems like there is a fair bit of side to side movement on the front and back bushes but I have no idea what unworn bushes feel like.

If worn is replacement DYI job or can anyone recommend someone to replace them for me?

Thanks in advance.

On a 1275, the front bush wears first.
When new there is .003" clearance, you can check yours easily with a dial gauge above it.
Original replacement bushes need to be line bored after press fitting, however there is now a slip-in silicon bronze bush for 1275s made by Minispares UK. It's available here from Karcraft, and Minis Plus.
To fit it, you put the primary gear in a lathe and machine the old front bush out. Polish inside with some wet/dry paper, and the new one slips in.
You sometimes have to reduce the bush length slightly, so it doesn't stick out the front.

I am running these bushes in both my 1360 and the 1412, no probs yet and the 1360 has done 11,000 miles on one.

[edit] http://www.minispares.com/Product.aspx? ... 676&title=

http://www.minis.com.au/minis/catalog/p ... cts_id=975

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I 2nd the use of the floating bush

Thanks I'll measure it up and see what I've got.

Ok so I have measured the movement using a dial gauge above the primary gear above the front and back bushes. For the front I get 0.005" and for the back it's closer to 0.006".

What are your thoughts on the acceptable tolerances above the recommended 0.003"?

If both bushes need replacing it seems easier just to get a new primary gear from Mini Sport UK. They are about $180 landed. What do you recon?

I'd keep using it for a bit, it's not bad yet..
Measure the crank diameters where it runs, that may be part of the wear too.
Original diameters there were 1.625" and 1.500".

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks drmini. Just quickly measured the crank and get 1.625" and 1.500" so it's spot on. I'll use the primary gear as is (after I check the end float).