No Spark

rakehill · June 15, 2014, 09:34:59 AM

Thanks Guys, you are correct, I spoke to Tony who diagnosed a shellac problem. The magneto is now with Dave Lindsley who took it apart while I was with him to confirm the diagnosis. Dave is going to repair it for me but the episode has scuppered my plans to bring the bike to the annual rally for the first time.

Davetom · June 13, 2014, 11:43:33 PM

Sorry didn't intend to sound negative about Tony Cooper, nice bloke and did a great job on the Lucas KNR1 mag on my Ariel HT, so he was first choice with my Sunbeam mag, but he said he said he hadn't got the parts to repair it so went to Dave Lindsley

phutton · June 13, 2014, 02:16:20 PM

I think your machine has a Best & Lloyd pump. If it has, you will need to remove the pump internals to be able to get at the third screw holding the pump body on. It took me ages to find why I couldn't get my pump off first time!

Paul

VicYouel · June 13, 2014, 07:51:33 AM

The old windings used a shellac varnish to insulate the coils...... have to withstand anything up to 20,000 volts! With heat and age the old materials simply decay and break down. They finally melt and solidify after a long hot run.

Tony Cooper has a very good reputation......... could try Dave Fisher at Moathouse magnetos........ he knows what he is doing. APL in Shaftsbury tend to concentrate on magnetos from the thirties and onwards. Prices can vary widely.

Some times you are almost persuaded to dismantle the bike on both sides to fit that magneto and its inaccessible studs. Even the tool kit contained a special bent spanner.

Davetom · June 11, 2014, 05:08:36 PM

Just had a great job done on mine by Dave Lindsley, Tony Cooper didn't want to touch it as he said he didn't carry spares for them

rakehill · June 10, 2014, 10:30:22 PM

Thanks Vic, it seems that the magneto is solid and unable to rotate no movement in the slip ring or at the face cam end. I've got the mag off and you are right it is a bit of a job! I think I will take it to Tony Cooper and ask him to look at it for me. I'm already thinking that it will be a fiddly job to fit it back on the bike, there's hardly any room to access the studs beneath to fit the bolts on. I still don't get why it would fail after the Banbury ride, good job that I didn't stop it en route I suppose!

VicYouel · June 10, 2014, 08:23:10 AM

Might be just the points closed up so worth a quick check. It is a classic symptom of a failed magneto though. Failed winding or bearing insulator.

What a pain it is getting the magneto off the bike though!!!

Vic

rakehill · June 09, 2014, 09:36:41 PM

I completed the Banbury Run yesterday on my 350 cc side valve 1929 Model 2. The bike went great even pulled up Sunrising Hill! My problems started at the finish when I stopped the bike to sign in. When I went back to it I couldn't get it going to get back to the van. The plug looked great but still no spark, petrol ok. At home today I swapped plugs and checked the HT but still no spark. I began to take off the magneto which is a CMA ML type but couldn't move a couple of screws holding the timing case cover. The screws are the two that also look as though they hold the oil pump as well. Rather than do any needless damage i decided to leave it for a bit and think it through. Any advice from fellow club members would be really appreciated. Is the magneto likely to fail as soon as the bike stops after running for 3 hours without any trouble?