Author Topic: Setting my mag. Dumb question  (Read 956 times)

Offline Dunney

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Setting my mag. Dumb question
« on: 18.04. 2013 19:00 »
I am sure this is a dumb question and I have scanned the previous mesages with no luck so forgive me if this has been asked and answered before.

On a K2F with a manual adv/retard the timing ring has a lift ramp to activate the points at the top and the bottom.  Looking from the points end of the mag you have the pickups at about 10'o'clock and 4 o'clock..  If  set the timing for the left hand cylinder based on the bottom ramp, is the correct pick hole for the left hand cylinder the one at 4 o.clock (the back of the mag)

Have tried leads on both ways and it won't start but does occasionally back fire in 2 into 1 pipe.  I have obviously done something wrong but it would help to know Ihave the leads the correct way around.  Obviously as I have a 2 into 1 I don't know which side is firing albeit int he wrong place.

Stephen
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Offline Beezageezauk

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Re: Setting my mag. Dumb question
« Reply #1 on: 18.04. 2013 19:54 »
Heyup Dunney,

I can't remember if I've officially welcomed you to our friendly forum.  I bid you welcome (again) anyway.

I've had to double check myself so the following is from the BSA Service Sheet no. 203 and I've tried to simplify the method.

Set your engine so that the right hand piston (gear side) is just before the top of it's compression stroke with both valves free.  You know the exact setting for your engine.

Now, looking at the contact points....set them so they are opening at about 10 o'clock and the rear pickup will be for the right cylinder.

Remember at the points end the magneto rotates in a clockwise direction and have your A/R lever in the fully advanced position as you set your points to "Just Opening".

Good luck with this and the weekend of the French BSAOC re-start!!

Beezageezauk.


Offline Dunney

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Re: Setting my mag. Dumb question
« Reply #2 on: 18.04. 2013 20:02 »
Fine, so it the top ramp is set to the right hand pot then the back pick up will be for the right hand side.  Great much appreciated.  Now to work out what I have done wrong.

Merci beaucoup.  Trying to get the fleet up and running before our rally over here next month.


Dunney
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Online groily

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Re: Setting my mag. Dumb question
« Reply #3 on: 18.04. 2013 21:11 »
Don't want to take issue with the service sheets Beezageeza, and I've been easy on the vin rouge today, but in fact the lower cam lobe - 4 o'clock-ish looking at the cb from the drive side - should normally operate the rear pick-up (gearbox side) on any K2F. So to fire the rh cyl from the rear pick-up, yup, get the timing side on compression and the points just opening on the lower lobe of the camring. Remembering the cb turns clockwise as you look at it face-on, so you get it on the opening ramp going the right way, not the closing one going the wrong way (which has been done a few times!). And, with a manual AR, to have the camring fully advanced (which will be with 'slack cable' if the cable enters the mag on the front (left, or engine) side looking at it from the left of the bike. It should.
You can see whether a cylinder is on compression or not, because towards tdc on the other (ie exhaust) stroke, the valves are visibly open through the plug 'ole. So your left hand cyl's valves should be visibly open while playing this little game.
Not a big problem, you can time it equally well on either cylinder, and swapping the leads from one plug to t'other will solve any problem (after the little backfire that may possibly occur from kicking it over the other way!)
Cheers, Bill
Bill

Offline Beezageezauk

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Re: Setting my mag. Dumb question
« Reply #4 on: 18.04. 2013 22:35 »
Hey Bill you may well be right. 

The sheet does state that you set up on the bottom cam but the tiny diagram within actually shows a couple of close lines that I've taken as the points gap and these lines are at 10 o'clock.  I'd need a magnifying glass to see it properly. 

Now if the heel is at 4 o'clock...will the points be at 10 o'clock?  I've had a bit of a gargle myself now!!

Dunney:- As Bill mentions, swapping the leads from one plug to the other will resolve it.

Beezageezauk.

Online Ted_Flash

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Re: Setting my mag. Dumb question
« Reply #5 on: 19.04. 2013 08:10 »
Lots of assumptions being made with these methods.

With the points just about to open, get a mirror & flashlight and check which hole the brass on the slip ring is visible at.  The lead from that hole should go to the cylinder that's at TDC with valves closed.
Ted Wilkinson, Ramsbottom, Lancashire
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Offline Dunney

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Re: Setting my mag. Dumb question
« Reply #6 on: 19.04. 2013 08:38 »
Ted, Good call. Obvious really but too obvious for my small tired brain.

Dunney
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