I ran the M20 today for about 15 minutes. Oil started leaking between the generator and the casing. I stopped the engine and on checking found the generator could be moved by hand. How is it secured in it's casing and what should I do to secure it.

email (option): araine11@hotmail.com

Arthur are we talking WM20? The generator (dynamo) is mounted on top of the magneto. So not sure what you mean. Can you explain your problem better. Ron

email (option): ronpier@talk21.com

The oil appears to be coming out behind the cover where the shaft from the driving gear goes through the back cover and into the mag-dyno. The whole mag-dyno assemble can be moved a little even though the strap appears to be tight.
What keeps the shaft tight onto/into the backing plate? Is there an oil seal in there? I have taken the timing cover off and checked the nut on the end of the shaft which appears to be tight. I do have a tool to take the timing wheel off if I need to. I would then have to set up the timing which I haven't done before. I do have lots of instructions for this exercise. If I move the assembly about it shows in the gear wheel moving so something has come loose somewhere hasn't it?

email (option): araine11@hotmail.com

Yes Arthur there should be an oil seal in the cover where the mag pinion shaft goes through into the timing chest. The only thing that keeps the magdyno tight is the strap with the trunions and 5/16" bolt. However there should also be four locating dowels on the bottom of the mag that sit in their four respective slots on the mag platform. It is not uncommon for the mag platform and slots to get damaged and out of shape by running with a loose magdyno. I suggest you remove it for inspection. Put your findings (with pictures if poss) on hear for analysis. Regards Ron

PS you can send pix to me, Rik, Henk or someone if you haven't worked out the white man's magic

email (option): ronpier@talk21.com

Thanks Ron will investigate Sunday.

email (option): araine11@hotmail.com

Just a couple of things the check before you remove anything Arthur. first thing to check is that the strap has not stretched and the 2 ends of the straps are touching each other when the bolt is tight.
The other thing is that when the bike is run with a loose magneto it wears the crankcase where the magneto sits, as Ron says under the mag there are 4 little dowels that locate in the crankcase. If the magneto is loose it will wear the crankcase and the bottom of the magneto, if this has taken place it will take up the backlash between the 2 gear wheels. So before you slacken the magneto take the timing cover off and check for backlash between the 2 gear teeth. If there is no backlash you are loading up the magneto bearings and the mag will not last long. You can buy shims to rectify this from eBay, you can also buy a new oil seal.
Once you have re timed it and the mag strap is tight check for backlash between the gear wheels.

Tim W

email (option): t.j.walker@btinternet.com

The local magneto guru down here, Peter Scott (www.dropbears.com/p/peterscott/rudge) fits new pins for mounting the magneto that have a bottom like a woodruf key so they fit tight into the old floged out dished shaped slots in the crankcases.
They are a little shallower , as if you got a key of the correct with & length then ground 1/4 off the front & back so you can still adjust the position along the axis.

He is also the local Rudge Guru since Rob Hart departed for his last ride.
So these could be standard Rudge fitments.

He did tell me what they were off when he fitteds them , they were not cheap but then neither are magneto pinions and crankcase repairs. been in there for about 8 years ( pushing 40,000 miles ) and not had a scrap of bother so well worth the money.

Bike Beesa
Trevor

email (option): wariron@tpg.com.au

It is great to have guys like you out there and I for one really appreciate it.
I have looked at this problem further and can advise that on checking the straps I was able to get a turn and a half on the nut which seems to have secured the mag/dyno and removed any play there was. there is a very small amount of play when turning the gear wheel but it looks to the untrained eye that there is no wear anywhere. I could put it all back together as I have a new timing cover gasket but with oil leaking from that rear oil seal even though it was only for a short period of time could it now be damaged. I do not know what the quality of oil seals there was back then. The bike has been standing since 1968 and I have only done a few runs down a lane next to me so I am still in the early stages of re-commissioning. What do you think?

email (option): araine11@hotmail.com