E: Engine Plug problems

[Howard]

Has anyone had plug problems lately?

Couple of weeks ago I rode about 10 miles in traffic and parked the Egli. Half an hour later I started it and it would only run on one cylinder - duff rear plug.

Saturday I went to the club shop (80 miles each way) travelling about 50/60 mph with Comets in tow. I left them about 10 miles from home for a quick thrash to blow out the cobwebs, and about 2 miles from home the rear plug packed in.

First one was a well used AC, the second one was a brand new old stock Lodge.

Have I just been unlucky? I'm now carrying spare plugs for the first time in 30odd years.

H

 

[greg brillus]

I'd be looking at other items on your engine, either ignition or carb related.

 

[Bob]

Is the rear plug fouling with carbon/oil deposits, and then when cleaned will it do another few miles before fouling again?
I had the same problem with my Rapide and tried hotter plugs, re-installing restrictor wires in the oil feed, all to no avail.
I cured the problem by installing new valve guides, in this case the sealed type from VOC spares, using tips and instructions from this forum.
I've had no problems since.

 

[chankly bore]

As a stop-gap try parking the machine on the right-hand stand, and perhaps only going on roads with right-hand bends. This cuts down pooling of oil around the lower valve guides. Seriously though, sealed valve guides are brilliant. What's the compression like?

 

[Albervin]

What sort of ignition system are you using? A repetitive problem like this surely must lead to the source of the problem being other than the plug.

 

[Howard]

New valves and sealed guides about 5000 miles ago.

Same grade of plug I've used for 40 years.

Carb settngs the same for 3 years. No obvious running problems anywhere in the rev range.

Only got a left side prop stand

Pazon ignition with single double ended ignition coil.

And I haven't changed anything else lately.

 

[erik]

sorry for my english ,but i would Change the Piece between the sparking plug and the high Tension cable. (in german :zündkerzenstecker).in this part a resistor is mouted and over the time you will have a weak spark.regards erik

 

[vibrac]

As a stop-gap try parking the machine on the right-hand stand, and perhaps only going on roads with right-hand bends. This cuts down pooling of oil around the lower valve guides. Seriously though, sealed valve guides are brilliant. What's the compression like?

That RH side stand parking was originally recomended by one George Brown recounted in a old MPH he said it also kept the cams lubricated I suppose when you are testing them every day winter and summer.....

 

[Howard]

sorry for my english ,but i would Change the Piece between the sparking plug and the high Tension cable. (in german :zündkerzenstecker).in this part a resistor is mouted and over the time you will have a weak spark.regards erik

That's an interesting one, Eric. When I changed the first dead plug, I replaced both non resistor plugs and both resistor plug caps.

I had wondered if it was the too much petrol/lack of insulator glaze problem, but I've never had chokes and always flood the carbs for the first cold start.

I'm going to give the dead plug a good looking at, followed by a good talking to, and a sound thrashing (maybe the sound thrashing was what caused the problem in the first place).

 

[Simon Dinsdale]

I know of several people who have had double ended ignition coils pack in. Initially they keep going but start to misfire at high revs and then slowly get worst. If the spark is weak at high rpm then that wouldn't help. One owner ended up with the ignition coil melting. Sorry i don't know what make the coils were.