Plug leads '54 Dommy

Previously wrote:

I have hadthe magneto overhauled on my 1954 Dommy, its a few month since I took it off and have forgotten which lead goes to which cylinder

Hi Michael,

First of all I'm assuming that the magneto has been timed and the valves are set correctly. Remove the spark plugs to make it easier to turn the engine (minus the compression strokes), remove the rocker covers and the magneto pick-ups. Slowly turn the engine while watching the rockers and set the engine at a point where the both valves on one side are opening/closing. At this point these valves should both have zero gaps while the valve clearances on the other side should have a normal gap (the rockers should rattle up and down freely). The side with the clearances is now at approximately 'top dead centre' before the ignition stroke. Check through the hole where the mag pick-ups fit and look for the copper insert which is set into the slip-ring (you may need a small torch and a mirror). If you can see it then that HT lead goes to the cylinder with clearance on both valves. If you cannot see the copper insert it will be on the other side (the one that is impossible to check due to it's position) so that one would be the lead to the cylinder with valve clearances.

I hope that all makes sense, Rob.

Previously wrote:

Previously wrote:

Hi Rob,

Many thanks for the clear guidance, I have set the timing using a long stemmed dial gauge for TDC and a degree disc for the 32degrees BTC for the points opening.

Again, many thanks,

Mike.

Previously wrote:

I have hadthe magneto overhauled on my 1954 Dommy, its a few month since I took it off and have forgotten which lead goes to which cylinder

Hi Michael,

First of all I'm assuming that the magneto has been timed and the valves are set correctly. Remove the spark plugs to make it easier to turn the engine (minus the compression strokes), remove the rocker covers and the magneto pick-ups. Slowly turn the engine while watching the rockers and set the engine at a point where the both valves on one side are opening/closing. At this point these valves should both have zero gaps while the valve clearances on the other side should have a normal gap (the rockers should rattle up and down freely). The side with the clearances is now at approximately 'top dead centre' before the ignition stroke. Check through the hole where the mag pick-ups fit and look for the copper insert which is set into the slip-ring (you may need a small torch and a mirror). If you can see it then that HT lead goes to the cylinder with clearance on both valves. If you cannot see the copper insert it will be on the other side (the one that is impossible to check due to it's position) so that one would be the lead to the cylinder with valve clearances.

I hope that all makes sense, Rob.

Hi Mike,

I,m sorry to be a harbinger of bad news but the timing data for the Dominator '88' is 30 degrees before TDC and 32 degrees for the '99',

Regards, Rob.

Previously wrote:

Previously wrote:

Hi Rob,

Many thanks for the clear guidance, I have set the timing using a long stemmed dial gauge for TDC and a degree disc for the 32degrees BTC for the points opening.

Again, many thanks,

Mike.

Previously wrote:

I have hadthe magneto overhauled on my 1954 Dommy, its a few month since I took it off and have forgotten which lead goes to which cylinder

Hi Michael,

First of all I'm assuming that the magneto has been timed and the valves are set correctly. Remove the spark plugs to make it easier to turn the engine (minus the compression strokes), remove the rocker covers and the magneto pick-ups. Slowly turn the engine while watching the rockers and set the engine at a point where the both valves on one side are opening/closing. At this point these valves should both have zero gaps while the valve clearances on the other side should have a normal gap (the rockers should rattle up and down freely). The side with the clearances is now at approximately 'top dead centre' before the ignition stroke. Check through the hole where the mag pick-ups fit and look for the copper insert which is set into the slip-ring (you may need a small torch and a mirror). If you can see it then that HT lead goes to the cylinder with clearance on both valves. If you cannot see the copper insert it will be on the other side (the one that is impossible to check due to it's position) so that one would be the lead to the cylinder with valve clearances.

I hope that all makes sense, Rob.

Hello The Timing for a 500cc Twin Is 30 degrees before top dead center a timed from the drive side left hand cylinder and the plug lead for the drive side is the back lead or the one nearest the battery box Hope this Helps ! Yours AJD

The book timing should only be considered a guide. Get her running and then adjust appropriately.

Cheers

Alan

Now this may sound a bit stupid, but, you only have two choices. Forget which lead goes where. Set up the timing (As if you DID know). Connect the leads, if the engine does not start, or you get an explosion in the exhaust, swap them over. Bingo! I too have a '54 Dommy ( A nostalgia trip to my distant teens, when I owned a '53 model).

Hope you get it running OK, and enjoy many happy miles.

All the best, John.

Previously wrote:

Hi Rob and Anna,

My Norton manual says 32 degrees BTDC the timing disc says 30 degrees BTDC, thanks for clearing that up, fortunately I had not replaced the timing chain cover so it was easily rectified.

Again thanks so much for your help,

Mike.

Hello the manual is wrong If you read it this reefers to the big twins 600. 650. 750. Not the 500 it as a shorter stroke too the other twins so its 30 degrees before top dead center and all twins fitted with a magneto are timed from the drive side So that means the left hand plug lead is the nearest to the battery box and the right hand is the nearest to the barrel base if you keep this in your head you can not go wrong ? I have two 54 dominators

I once had a 1954 88 but sold her in 1969. She had a good reg. no. RTA88! Didn't bother about things like that then.

The timing needs to be reconsidered if running a non-standard compression ratio. Retard the ignition if higher CR. I think RTA88 ran at about 29 BTDC on a CR of 9.5.

Check the timing on both sides. I have never had a Norton twin that was the same on both pots. Average them out and it's near enough for a road bike.

You are probably using the automatic advance mechanism. I always prefered the manual set up used on the later SS machines as it's easier to get the timing right by road testing.

These days I use electronics but then I don't care a fig for originality!

Good luck

Alan