Barstock single cylinder in metric

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coulsea

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When it comes to stating a new engine the only way I can do it is with an electric drill, sometimes the cordless drill is not fast enough and I have to resort to the plug in type.
IMG_2236.JPG
I have 3 sizes 6, 8 and 12mm, they are made by drilling a hole a couple of mm below the top and then with a round file the same size as the hole file a grove half a hole out, when it breaks through to the original hole it will naturally work its way around to give a curve.
 

coulsea

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Johno1958

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Congratulations
Very nice engine
 

Maksi

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Very nice engine. Congratulations.
What is the TDC spark time and the BDC exhaust valve time?
Thanks.
 

coulsea

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Very nice engine. Congratulations.
What is the TDC spark time and the BDC exhaust valve time?
Thanks.
Timing can get very complicated if you want maximum performance from an engine but an engine like this is just for display and self satisfaction so whatever I say is going to be wrong to someone somewhere.
my view is that for getting it running the first time the ignition timing should be at or just before TDC, this will give the spark at the highest compression even if the valves and rings are leaking a bit. the exhaust valve should open at BDC and close at TDC, the length of time that the valve is open can be adjusted a bit by changing the rocker to valve clearance. I think that the most important time is when the valve closes because you really want the full intake stroke to maximise air flow through the carb particularly if you are already losing a bit through leaking valves and rings.
once it is run in and everything seals properly the ignition timing can be advanced to after TDC which will reduce power and make it run a lot smoother with less bang and less heat generated.
one day I will try an adjustable timing setup, the timing should be different for starting, just ticking over or producing power.
 
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