Magneto magnet strength

[Tigercub]

For a very long time now my G80 has played up warm starting. Starts first or second kick when cold and the same when hot. If I start it and run it for 5 mins on stand then try and start it...no chance. I've stripped the mag now. All looks pretty good for a 1952 magneto...all though it was supposedly rebuilt early 90's. I've bought an easycap and am about to strip the rotor to chop out original condenser. I just wondered how strong the magnets should be. I can't hang an M10 spanner of of mine.

[bitza]

Have a chat with Tony Cooper, he's in Halesowen West Mids, magic on fixing mags, Dynos.

[Tigercub]

I've emailed brightspark now. I can replace the bolt on parts myself, I don't need someone else to fit new bearings or undo some screws. I can't magnetise the original body. I find it hard to believe a 65 year old magnet is as strong now as it was when made. I don't want to put it back together without checking the magnets...they are after all very key to it working properly.

[aobp11]

Gareth, the magnets probably repel metric spanners
How did you test the strength? A spanner flat against the open side of the magneto body will drop off for sure since the actual magnets are deeper inside the body. I tested several spanners in a know to be good N1 body. Open end of body downwards and flat side of spanner head against the middle of one magnet pole. Spanner doesn't drop off. Not even with spanner head perpendicular to pole surface.

Albert

[Andy51]

Hi, My 18S and G80 (both '54, SR1 mag) have the same issue - great starting cold or hot, not so good warm. I find they start OK when warm if well flooded. Sorry to sound if I'm teaching grandmother to suck eggs, have you tried flooding the engine (tricky to differentiate between flooding and drenching, I know)? The carb could be at fault too, I fitted a replacement new carb this spring and it makes starting much easier. Andy

[Rob Harknett]

Something to consider? With manual AR you need to start with the lever retarded when cold. Or it will kick back and be difficult to start. Once warmed up, you just leave the lever fully advanced. If fully retarded, the engine does not want to start. Now on to SR1 mag with auto advance. Which is always in the fully retard position upon starting. OK when starting from cold. However, if it is sticking closed, or almost. The bike will not want to start when hot. Check that first, open it by hand and see if it snaps shut quickly when released. If that's OK its quite a simple job to fit a new condenser. I assume points and lead have been checked. Pull the cover spring clip out a bit and clean + the contact stud on the coil. Perhaps also remove the lead from the cover, cut a bit off the lead and replace the pointed screw in a new part of the lead.

[Tigercub]

Thanks for replies. I guess the mag is just something I want to eliminate. I've tried every method of starting it possible. Flooding it, putting a choke on carb, all positions of the advance lever, you name it I've tried it. Just a single phut would be nice but I get nothing, it's like its completely dead. Leave it too cool and whumph...first kick. Take it out for 20 mins, stop at a shop or for petrol..whumph..first kick. Go to a bike meet, have 2 cups of tea and a chinwag...clasp hands together and pray...25-30 kicks later maybe a phut. Then it will go. I now need a shower and a lie down though before I can go anywhere..haha.

[clive]

Have you actually checked the plug to see if it has a good strong spark when your problems occur? This may help you to establish if the mag is at fault.

[Rob Harknett]

I lost my way a bit, somehow thought we were dealing with SR1 mag. I have never had a problem with N1 mag. I have had similar problems with a car. But with the car the engine has died, then will not start again until cold. The condenser needed replacing. If you have not changed the plug, I would certainly try that option. Todays plugs are rubbish, no good if you have been cleaning them.

[Tigercub]

I bought 4 brand new plugs, i'm a 2 stroke nut, plugs are the bain of my life. I agree, once they've been 'oiled' these days then cleaning them seems to be a waste of time. Something in modern petrol seems to destroy them. I've just had another go with a steel rule on my magnets...hopeless... one is better than the other but both seem very weak. Any way it's getting boxed up now and sent to Bill in France...see what he says.