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Re: Magneto oil leak

38x20x7(or8)
Is the normal one who can installed.

Roy

Re: Magneto oil leak

Roy is correct but the oversize seal may get you out of trouble without machining the case or resorting to 'glue'...They are cheap so I would get both and experiment a bit....Ian

email (option): ian@wright52.plus.com

Re: Magneto oil leak

Thanks all for your comments and help. I have examined the seal housing and it is oval. A 38 seal will rattle around unless I glue it in place. I may have to grind a bit to get a 40 seal to fit. The mag platform slots are also worn, so the mag pulls to the side. It also rocks a bit. This does not affect the gear meshing but the seal won't be happy.

So my plan is to get the mag to sit firmly on the platform, on the correct center-line and without sideways movement, then shim to get the right gear mesh.

Then I can experiment with seals, failing which I make up the external screw-on seal flange (drawing 65-2136). I have a few thoughts on modifying this slightly to make it easier to make and fit. This is the subject for another post and if it comes to that I will keep you posted.

email (option): pvlietstra at gmail

Re: Magneto oil leak

On my B33 the hole that the seal sat in was worn. I made sure that the mag-dyno was sitting right, then I smeared J B Weld around the seal and pushed it into place. Once this was set I was able to use the bike without oil leak. That was done about 10 years ago.

Re: Magneto oil leak

My bike came to me with a wobbly mag, which allowed oil to blow all round and into the mag itself. I idiotically overtightened the mag strap and broke it. When I finally got round to fixing it properly I used gasket paper under the mag and cut an extra piece for under the outboard end to get the mag shaft to line up properly with the engine seal. I can take no credit for this, I was advised to do it. Anyway it worked.
The magneto was wobbling on it's centre by the way and the seal housing was worn unevenly but fillable with a tiny bit of non hardening sealant. I think the case had been welded

email (option): jeremy@clogmaker.co.uk

Re: Magneto oil leak

The problem with completely machining away the recess for the seal to do the REME mod is accurately locating the correct centre of the newly machined hole into which the brass/aluminium seal holder will fit...

I made a jig for doing this job using a NOS set of crank cases to determine the correct location of the centre...
Another way which might determine the centre accurately enough would be to clamp the mag in place and then fit the mag gear...After adjustments to produce the correct gear mesh and with the mag straps fully tightened the gear could then be removed and the outside diameter of the magneto shaft clocked true...

This would require half the crank case to be mounted on parallel blocks with the mag attached and to be clamped to a milling machine table I would have thought...Obviously once the shaft is clocked the crank cases can't be moved in relation to the milling machine spindle..Ian

email (option): ian@wright52.plus.com

Re: Magneto oil leak

To find the center, I plan to fit the mag, mesh the gear, strap down and then remove the gear. I will machine a dummy sleeve to fit snug on the mag shaft and with the correct OD for the mod cutout. I will mark out around the OD of the dummy sleeve.

email (option): pvlietstra at gmail

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