Dommie 99 ignition timing

With modern fuel, I would recommend 30 / 28 degrees. A cam ring with a difference of 2 degrees is acceptable. If you really want to even things up, lots of careful work on the cam ring with a fine stone is required.

My K2F mag has just had a newly wound armature, new condenser, bearings and seals and been generally refurbished.

When setting the ignition timing to 32 degrees BTC on the left hand side I get a reading of 30 degrees BTC on the right hand side. This being within the tolerences of the refurbishment

Is this an acceptable discrepancy (giving an average setting of 31 degrees BTC which some may prefer with todayâs fuels) or should a different setting be used.

Alternatively is it strongly recommended that the cam ring be adjusted to achieve the same reading on both cylinders.

If so, any pointers on how best to do this would be most welcome

Iâm not sure if I should be worrying too much over the original readings

your correct timing its 32 Degress fully advanced , Before TDC, on the Left hand side only, do not worrie too much about the right hand side, and set your magneto points to the nearest too the battery box pick ups of the igntion leads so the points should be looking down set the points too 12 thou, and a cig paper comes in handy this goes between the points from tdc turn your engine back to 32 degrees so you feel on the paper the points open and then close its is a fine point you feel the paper come lose as the points just opens and that 32 degree now lock of the locking bolt you should have you bob weights fully open for advance , now you should have the right timing once locked off on the ADT bolt now remove what ever you put in the bob weights to keep them open , then turn your engine over to tdc the points should fully open at 8 degrees after TDC hope this help yours Anna J

Do indeed worry about the timing on both sides. My first magnetohad such a bad slip ring that when the LHS was set to 32 degrees btdc, the RHS was at 57 degrees btdc. The fact that you know the timing on both sides shows that you are being both correct and meticulous.

32 degrees is fine if you have 4 star petrol.I would seriously suggest that with modern lower octane fuels you set no more advanced than 30 degrees btdc.

Thanks Gordon and thanks Anna.

I too have experience of incorrect timing between cylinders.

I had my first Norton, a 650ss in the mid 70âs and a neighbour offered to set the timing for me as I was mechanically inept at that time.

Having travelled about 10 miles two up on its first journey, the engine made a lot of clonking noises, cut out and petered to a halt.

Kicking the engine over the whole lot locked up. Suspecting the primary chain had come off and jammed I removed chain case only to find everything as it should be.

Having got it home I removed the cylinder head to find the right hand piston missing!

I found it in bits lying in the bottom of the engine with some of it trying to escape through the crankcase. A right mess. Iâve kept most of the piston remains as a souvenir!

A chat with my neighbour revealed that he had timed the left hand cylinder and assumed that the right cylinder would be correct.

Still, £15 bought me a replacement motor (£60 paid for the engine and the remains of the original sold for £45). Those were the days!

I have another mag which fires 180 degrees apart but suspect a problem with the armature windings.

The bike runs fine with this mag but has a tendency to randomly cut out, usually when slowing down to stop at junctions, traffic lights, etc and will not start again until it has cooled down, usually after about 20 minutes â very frustrating. Iâm not sure what else would cause this to happen.

I have had the condenser replaced but this doesnât seem to have made any difference.

Anyway, Iâm hoping the replacement mag will prove more reliable.

Hello your engine symtoms are like the condencer has failed or its not been fitted in the right way have it cut out and fit easy end caps from brightsparks, that sould sort it, time her up has before, hope this helps

yours anna j

Is 32* BTDC the correct timing for a 650SS too?

Yes, but see my posting above.