Author Topic: manual k2f ignition  (Read 1044 times)

Offline Davmacb

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manual k2f ignition
« on: 10.10. 2015 17:25 »
I am totally confused.  Having had numerous problems with electronic ignition I have decided to return to the magneto system and have recently bought a rebuilt manual k2f.  There seems to be some confusion whether the ignition is fully advanced with the cable pulled tight or the cable loose.  I have read conflicting reports that the lever should be pulled towards you for the retarded position and others that it should be pulled towards you for the advanced position.  Can anyone shed some light on this?

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Re: manual k2f ignition
« Reply #1 on: 10.10. 2015 17:58 »
The vast majority of manual K2F's are 'slack advance'. When looking at the points the cable take off is usually on the left hand side, with the cable exiting upwards. The points rotate clockwise. The cam ring is attached to the cable via a plunger with a mushroom head which is spring loaded to force the cam ring into its fully advanced position. When you pull on the lever, therefore tightening the cable, you are pulling the cam ring in a clockwise direction which makes the heel of the points hit the lifting part of the cam ring later, i.e retarding the ignition. So, 'slack cable advance', 'tight cable retard'. Good luck with your magneto. If you need any help setting it up send me a PM or have a look at my website. Best Wishes.
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Online Triton Thrasher

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Re: manual k2f ignition
« Reply #2 on: 10.10. 2015 21:52 »
Is it any simpler to say that rotating the cam ring in the opposite direction from that of the rotating points is advancing the spark?


Offline duTch

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Re: manual k2f ignition
« Reply #3 on: 11.10. 2015 01:36 »

 
Quote
There seems to be some confusion whether the ignition is fully advanced with the cable pulled tight or the cable loose.  I have read conflicting reports that the lever should be pulled towards you for the retarded position and others that it should be pulled towards you for the advanced position.

 Assuming the lever is mounted on the left bar, what B-Macc says applies, in the unlikely event it's mounted on the right side, would be opposite... *eek*
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Re: manual k2f ignition
« Reply #4 on: 11.10. 2015 08:31 »
Hey Dutch! It doesn't matter which side the lever is mounted, you have to pull the lever to tighten the cable so it's still slack wire advance. Don't confuse the guy!
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Offline duTch

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Re: manual k2f ignition
« Reply #5 on: 11.10. 2015 10:02 »

 Sorry, just'm pointing out a possible oversight of the obvious...
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Offline Davmacb

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Re: manual k2f ignition
« Reply #6 on: 11.10. 2015 19:17 »
Many thanks to all you guys who answered my query.  Age does rotten things to the memory banks.  Time was when I would be answering problems instead of asking them.

Online RichardL

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Re: manual k2f ignition
« Reply #7 on: 11.10. 2015 19:35 »
Hey Dutch! It doesn't matter which side the lever is mounted, you have to pull the lever to tighten the cable so it's still slack wire advance. Don't confuse the guy!

This is interesting stuff and just about everyting I know about it came from reading Andy's explanation. So, you can be d*mn sure I am not debating Andy (you), but there is one point to what Dutch said that seems to need clarification (not by me). Looking at the available levers, it appears that if you mount the lever on the left, for thumb operation,  you draw it toward you to pull on the cable. If mounted on the right, again for thumb operation, it would need to be pushed away from you to pull on the cable. Am I missing something here, like, can buy left or right levers, or change the lever assembly depending on which side it is mounted on?

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Re: manual k2f ignition
« Reply #8 on: 11.10. 2015 19:59 »
Levers are handed, just like the brake and clutch (though the handing of these is more subtle), you pull on them to tighten the cable. Pic attached.
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Offline duTch

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Re: manual k2f ignition
« Reply #9 on: 11.10. 2015 22:00 »

 I didn't mean to complicate this, and I also not dissing B-mac, but Richard you did interpret that as I intended, in the case of mounting a lever on the other side for which it was intended(in this case L→R)...Lots of intent- none ill.....groan  ...I can see me digging myself in a hole here *conf*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online RichardL

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Re: manual k2f ignition
« Reply #10 on: 12.10. 2015 00:26 »
Levers are handed, just like the brake and clutch (though the handing of these is more subtle), you pull on them to tighten the cable. Pic attached.

Aha!
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Online beezermacc

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Re: manual k2f ignition
« Reply #11 on: 12.10. 2015 08:58 »
Actually, going back to the original question, I think the confusion arises from information relating to MO1 magnetos which are for singles like the B31 and Gold Star etc. These magnetos were available with either 'slack wire advance' or 'tight wire advance' in fairly equal numbers, the 'slack wire advance type' being generally later versions of the same magneto for BSA applications. The benefit of 'slack wire advance' is that the normal running position for the magneto (i.e. when the bike is cruising and in most normal running situations) is the fully advanced ignition position, so, if the lever is inclined to slacken off due to vibration or lack of friction the magneto defaults to its fully advanced position. Owners with 'tight wire advance' were regularly complaining that they found themselves having to check frequently that the lever hadn't slipped, causing the magneto cam to slide into a retarded position which causes the bike to overheat and blue the exhaust. K2F magnetos, for twins, nearly always rotate anticlockwise (so the points rotate clockwise), Royal Enfield and Vincent being the only exceptions which spring to mind easily. The popular, anticlockwise mags, have cam ring housings with the cable take-off on the left hand side pointing upwards so that pulling the cable turns the cam clockwise therefore causing the points heel to strike the lift later, i.e. retarding the ignition. Cam ring housings with the cable take-off on the right hand side are extremely rare and are usually intended for R.E. and Vincent models to enable 'slack wire advance' for clockwise rotating mags. I think I've probably killed this thread off now as everybody has fallen asleep and I'm going to get nominated for the 'Dull Men Calendar' - see other thread, very funny!
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Offline muskrat

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Re: manual k2f ignition
« Reply #12 on: 12.10. 2015 09:37 »
How could you be dull, playing with all those sparky things. :o
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