Topic: Educate me about points gap range

[Pecantree]

Posting this here cause it applies to any bike with points.
But I'll use the 750 for illustration.
The range given for points gap is .012 to .016.
I just split the difference and set them at.014.
How does using a smaller or larger gap affect the engine.
Will using .012 make the engine run leaner or richer and setting at .016 make it the inverse.
What difference does it make?

Not trying to be snarky, I want to know why!

Thanks Ya'll
Steve

[Bailgang]

I split the diff at .014" as well but it has to do with dwell or the amount of time the coil has to re-energize between firing. Hopefully TT will see this and explain it better than me.

[dave500]

the gap closes up over time as the rubbing block wears,set them too small and the gap closes up quicker,set them to the wide side and you get more time out of the gap,the timing will shift as the blockwears aswell,you can get away with resetting the timing only and leaving the gap alone.

[2wheels]

I thought it has to do with the points themself getting hot, but here is a description I like.

Correct points setting involves both the opening moment and the fully-open gap. Because the points are opened by a cam, the gap determines how long they are open and how long they are closed. The closed time, or dwell, can be thought of as the 'charging time' for the coils, where too much will overheat them and too little will result in a weak spark. Dwell is not specified by BMW, but a proper points gap will result in about 78° dwell for most bikes, 110° for some early ones.
-this came from here (many thanks to the author) http://www.largiader.com/articles/ignition/

[Pecantree]

Because the points are opened by a cam, the gap determines how long they are open and how long they are closed. The closed time, or dwell, can be thought of as the 'charging time' for the coils, where too much will overheat them and too little will result in a weak spark.

THIS^^^^^^^^^
Explains succinctly.

Would some one set the gap smaller or larger for a specific reason? Racing?
Different coils?

Thanks.