magnetos

ddunderdale · Post by **ddunderdale** » Fri May 04, 2007 1:18 pm

Please can someone help me i have a 1954 AJS twin 500cc model 20 .Fitted on the bike is a K2F 42413 A mag ,in the B M S Spares book it says K2F 42230 A,can anyone tell me which is correct,Also as mine seems to be giving me problems can you tell me how much a new one will cost .The previous owner must have had trouble as there is a certain amount of damage inside ,ie the grease guards are broken and the bearings are shot.Hoping someone can help.Thankyou in antisipation. please could you email me as i am a novice on the computor and sometimes get lost on the site. my email is ddunderdale@hotmail.co.uk.THANK YOU.

Don Madden · Post by **Don Madden** » Sat May 05, 2007 3:01 am

The most accurate source of Lucas info is their equipment manual which lists the magneto as part no. 42230B/D.

The 42413a was used by 60-61 BSA twins, is CCW, manual adjust so should work as well.

Please get someone to help you navigate this site. The value of the information is incalcuble.

Cheers, Don.

ddunderdale · Post by **ddunderdale** » Tue May 08, 2007 10:03 am

Thankyou very much for the information Don i will now proceed to get the job done.(sorry for the delay replying but i was away the weekend).Thanks again. david dunderdale

Don Madden · Post by **Don Madden** » Thu May 10, 2007 9:10 pm

Hi, David. I receive a delayed PM as it was sent to our moderator, Eamonn Townsend instead of me.

The correct setup for the HT leads is for the rear lead to go to the off-side plug since the procedure is to turn the mag shaft such that the distributor, called a slip ring directs the spark energy there.

As the magneto sparks one of the leads each 1/2 turn, it can be timed to fire either side depending on the position of the armature.

The procedure to setup to fire the R/H side, (off-side to you lot), is handy as you can remove the rear pickup, and using a small mirror, turn the armature until the brass segment of the slip ring can be seen. This brass segment is what passes the high voltage to the pickups. & you can connect that lead to the cylinder that is at the top of the compression stroke & ready to make noise.

I remove a plug & place a thumb over the hole while turning the engine slowly. When my thumb is pushed off by pressure I know that piston is on the compression stroke.

Cheers, Don.

lawrence · Post by **lawrence** » Sat May 12, 2007 12:04 am

quote:

I remove a plug & place a thumb over the hole while turning the engine slowly. When my thumb is pushed off by pressure I know that piston is on the compression stroke.

Cheers, Don.

What an excellent tip!

ddunderdale · Post by **ddunderdale** » Wed May 16, 2007 11:10 am

the bike is up and running now so thanks to all who helped all i want now is a bit of decent weather to go out for a spin.thanks again. dave.