Starting procedure

I take the piston past TDC for both singles and twins before kicking as it then allows you to get energy into the flywheel with least effort.

In my experience  magneto ignition starting procedures benefit from starting the kick from just past compression . This allows the mag to spin faster and produce better spark . If manual advance is involved be sure to retard . Some prefer to advance spark slightly.

I always started my twins (Domi 99 and Commandos) from compression. That seemed to work well but all were coil ignition. But I am quite heavy. Singles - definitely follow the traditional technique.

hello for one, you should not be able to stand on the kick starter without moving, It should easy to kick over my  650 is easy to start  and I have two bad knees so your model 99 has some very high compression pistons  in somewhere around 10.1  your correct compression should around 7:9:1  for a model 99 try taken plugs out and start on left-hand side  only  and  then the right  and by then you got things hot and try both   yours  anna j

I'll need to check my notes for exact values but I seem to remember getting about 150psi on my 88SS.  That is about 10 atmospheres, but it is 'adiabatic compression' so the air heats up, which increases the peak pressure by perhaps 30% to 40% - hence the reading does not tell you what the true volumetric compression ratio is.  Mine is certainly less than 10:1 (more like 8:1).

Incidentally - is it safe to kick over with one plug removed if you have coil (including electronic) ignition?  If the HT cannot discharge over the plug, can it damage anything else?  Maybe I should ask in the electrics section.

I do know my low compression 16H with magneto starts more easily than the Dommie with electronic ignition.  I'm not surprised electric starters started to appear as higher compression engines became the norm.

The compression tester won't tell you the CR George. It will tell you if you have good compression or not, but I think you already know that, if you can stand on the kick-starter!

As for having 10:1 pistons fitted, it is very unlikely, particularly if the bike is otherwise standard. I should forget that.

Presumably it has magneto ignition, with automatic advance & retard? If so, it may be that the ATD is a bit sticky, and not fully retarding at rest. This will mean the ignition is a bit more advanced at start-up, which can cause kick-back.

When warm the starting effort should be easier, as the oil will have warmed, providing less resistance to your kicking effort.

I would be inclined to ease it over compression before giving it a good swing, as has been previously suggested.

Ian

Just to add my two ha'pence. I have a 1960 Dommi 99. The procedure I used when it was magneto ignition was to turn over the engine one full revolution (until it was just past tdc on compression) then give it good boot full and it generally fired up. Once I fitted electronic ignition I found starting much easier but it still needs to be just past tdc on compression.

When I got the beasty it had stood for 'several' years so for interest I did a compression test and got around 110psi averaged across both cylinders. After a general inspection I decided to de-coke the engine and re-seat the valves. On reassembly the compression went up to an average of 150psi across both cylinders. By the way it still starts as easily as already described.

The 'younger sister' of my Dommi which is owned by my soon to be son in law refuses to start using the kick start, it will only start by using the run and jump 'bump' start method, but that beast has a competition magneto with manual advance/retard.

John