Ignition and valve timing 650SS

For cam profiles and lots of other timing stuff, have a look at Dave Comeau's web site. He lists the Dommie SS camshaft. A dial gauge over the cam followers is easier to set up than one over the valves - if you already have the head off. It goes without saying that valves should not hit pistons

Camshaft

Part No I.V.O I.V.CE.V.OE.V.CStandard06-108450 BTDC74 ABDC82 BBDC42 ATDC

This data above, from Norvil, looks to be correct for the camshaft your engine should have inside it. Your camshaft is called a stock or sports special or standard SS. Is it possible that somebody has changed your camshaft? Please send some photos of it. Especially any markings on the side.

Your valve clearances should be inlet - 0.006" & exhaust - 0.008" This is important as anything less will possibly let the valves touch the pistons.

Your timing should be 32* with standard 650SS 8.9 to 1 pistons.(17839 inside piston skirt). Possibly 31* if you are using substandard fuel. ie unleaded. The Atlas engine used 7.6 to 1 pistons with 32* of advanced timing. But with HC Commando type 8.9 to 1 this has to be changed to 28*. The reason for this being that the wider bore of this engine moves the centre of the pistons behind the crankshaft.

There are several reasons why valves can touch pistons. Worn out or broken valve springs. over-reving the engine, wrong valve clearances and also if there is too much bore wear and the pistons can move sideways or rock. Perhaps the barrels need a rebore after 50 years of motoring?

Check out the attachment. It gives information about your camshaft (SS - Sports Special) and others fitted to Norton engines.

Attachments
camshaft-data-jpg

Previously janhakon_hansen wrote:

I have a few questions I hope someone can answer. The bike is a Dominator 650SS - 1964 with matching numbers, sold new to the European marked. It runs OK, but I do not get the power out of it that I think it should have.

Ignition timing: Shall fully advanced ignition be set to 28 og 32 deg BTDC? According to âHaynesâ the correct is 32 deg BTDC on all models except the Atlas with 9:1 pistons - 28 deg. The 650SS has 9:1 compression ratio and the same stroke length as Atlas. What is correct timing for 650SS with factory spec?

Camshaft and valve timing:

I have removed the head due to a broken exhaust valve spring. The timing is set according to the timing marks, but I notice that the inlet valves have just barely touched the pistons.

What is the correct valve lift in mm on a 650 SS camshaft (06-7817) and for the standard dominator camshaft?

What is the correct valve timing for a 650SS with the correct camshaft?

Ref.: http://www.norton.norvil.net/tech03.htm

Hi - assumong that the crankshaft sprocket is correcly lined up with the intermediate gearwheel, is the camshaft sprocket in the correct position, ie there should be 10 rollers between the marks at the top of the intermediate sprocket and the cam sprocket, the timing mark for which should then be at approx 11 o'clock.

I have a 1963 650 ss and these figures are as quoted in the worksop manual, and my bike runs fine and definitely does not hit the pistons!

Have you got a "Hot"camshaft fitted?

Good luck

Regards Terry

Previously janhakon_hansen wrote:

I have a few questions I hope someone can answer. The bike is a Dominator 650SS - 1964 with matching numbers, sold new to the European marked. It runs OK, but I do not get the power out of it that I think it should have.

Ignition timing: Shall fully advanced ignition be set to 28 og 32 deg BTDC? According to âHaynesâ the correct is 32 deg BTDC on all models except the Atlas with 9:1 pistons - 28 deg. The 650SS has 9:1 compression ratio and the same stroke length as Atlas. What is correct timing for 650SS with factory spec?

Camshaft and valve timing:

I have removed the head due to a broken exhaust valve spring. The timing is set according to the timing marks, but I notice that the inlet valves have just barely touched the pistons.

What is the correct valve lift in mm on a 650 SS camshaft (06-7817) and for the standard dominator camshaft?

What is the correct valve timing for a 650SS with the correct camshaft?

Ref.: http://www.norton.norvil.net/tech03.htm

Well you have the wrong camshaft , for a start the part number you should have for a 1964 650SS is part number 22729 witch is the Norton Manxman Camshaft As the Norton manxman was the first 650 to be built by Norton at Bracebridge street this Cam was use until 1969 where it changed to part number 061084 this was used until 1974 , part number 062608 was its replacement, and they all have the same timing , 50/74/82/42 . these are the correct camshafts from my parts book , and I see you have the wrong pistons as well the part number for the right pistons are numbers 24022LH &number 24023RH these where used to 1966, where they changed to part numbers 25387LH& 25388RH these would of been BHB pistons and replicated by Hepolite of the day the Ignition timing with a Lucas Magneto KF2C fitted should be 32% Before Top Dead Center , timed from the Drive Side with the ignition lead nearest to the Battery box is the Drive side OR Left Hand Side , The points should be facing up ward and point cam on the bottom of the cam ring please note you should have *8% degrees fully retarded and , please lock of the ADT to full advance before doing any timing , and recheck both cylinders Left and right hand-sides Before locking off the Center ADT locking sleeve Bolt this as a double thread Note I find that Bosch W7DTC spark plugs work the Best good hunting yours anna j

Previously janhakon_hansen wrote:

Thank you for helpful information so far. I will probably do the measurement next week. The engine had a rebuild before I bought it, and the pistons and barrels looks very nice. Re-bored and +060 pistons. I have not removed the barrels yet, and have no picture of camshaft available at this point.

The problem seem to be that the marked teeth on the intermediate and camshaft sprockets are positioned in the tenth spacing in the chain, ie only 9 rollers between the marked teeth. I will reposition and do the measurement of valve lift and timing.

Well at 60+ your barrel is over bored for a 650 , you should never bore a 650 barrel behoned +40 . as you risk splitting the barrel or cracking the bottom spigots and top spigots get very thin, Do take My advise and Get the Barrel re-sleeved back to Standard pistons BHB Yours Anna J

Previously anna jeannette Dixon wrote:

Previously janhakon_hansen wrote:

Thank you for helpful information so far. I will probably do the measurement next week. The engine had a rebuild before I bought it, and the pistons and barrels looks very nice. Re-bored and +060 pistons. I have not removed the barrels yet, and have no picture of camshaft available at this point.

The problem seem to be that the marked teeth on the intermediate and camshaft sprockets are positioned in the tenth spacing in the chain, ie only 9 rollers between the marked teeth. I will reposition and do the measurement of valve lift and timing.

Well at 60+ your barrel is over bored for a 650 , you should never bore a 650 barrel behoned +40 . as you risk splitting the barrel or cracking the bottom spigots and top spigots get very thin, Do take My advise and Get the Barrel re-sleeved back to Standard pistons BHB Yours Anna J

I suppose that it is a bit late to respond to this thread, but I will any way. I ran my 650 SS for decades on +60 pistons with the cracked spigots removed with a cold chisel as the cracks already went round half way round the bores. I didn't fit any flame rings in the spaces where the spigots went.

Regards,

Dave