Ignition timing and points setup

[olliegbr]

I have acquired a project bike build, 1973 import that has had an engine and carb rebuild.
The bike would fire but not start.
I'm checking the points and timing using the excellent method from Hackaweek;
Hackaweek CB750 points

I've set the points to 0.35mm - check.
I can set 1&4 by adjusting the large backing plate - check
I can set 2&3 by adjusting the smaller plate on the RHS - check

However, when I go back to 1&4 this is out again, by some margin.

Very new, (my first post) and not sure where I should be checking to solve such a problem.
The points don't look new, but have cleaned up well.

Thanks
Ollie.

 

[Robert Frere]

Let me get this right you are setting the points gap for 1+4 you do that via the small adjusting screw where the points attach to the back plate.and the same with 2+3 you then set the static timing using a inline bulb starting with 1+4attach one lead to the points and the other to earth turning the crankshaft clockwise the bulb should light as the f mark just comes to the static mark on the crankcase.move the backing plate to achieve this then 2+3the same only you only move the 2-3 points little mounting plate

 

[olliegbr]

Let me get this right you are setting the points gap for 1+4 you do that via the small adjusting screw where the points attach to the back plate.and the same with 2+3 you then set the static timing using a inline bulb starting with 1+4attach one lead to the points and the other to earth turning the crankshaft clockwise the bulb should light as the f mark just comes to the static mark on the crankcase.move the backing plate to achieve this then 2+3the same only you only move the 2-3 points little mounting plate

That is correct. I've tried the bulb method with the battery connected, then removed the connectors and used an Ohm meter instead of a bulb.
I can can get 1+4 correct with the back plate fully anti-clockwise.
I can only get 2+3 within a few degrees of 'F' (light on before F is at the mark). This is with the points fully clockwise. (Zoomed picture attached)

 

[1975 750]

I have acquired a project bike build, 1973 import that has had an engine and carb rebuild.
The bike would fire but not start.
I'm checking the points and timing using the excellent method from Hackaweek;
Hackaweek CB750 points

I've set the points to 0.35mm - check.
I can set 1&4 by adjusting the large backing plate - check
I can set 2&3 by adjusting the smaller plate on the RHS - check

However, when I go back to 1&4 this is out again, by some margin.

Very new, (my first post) and not sure where I should be checking to solve such a problem.
The points don't look new, but have cleaned up well.

Thanks
Ollie.

i understand if u want to keep it stock , I bought an electronic ignition from Dyna tech and never looked back … one less problem ….

 

[olliegbr]

I removed the tank and checked all the wiring. Then went through the whole process and reduced the points gap. Managed to get 1&4 spot on and 2&3 were a few degrees late static. Bike has never been started since the previous owner rebuilt the carbs and engine, (plugs were still brand new after I checked them as part of this process).

Bike fired up first turn, sounds ‘OK’ and quickly ran out of fuel left in the carbs.

Perseverance and stubbornness win the day!

Thanks, (there will be many more questions as I continue this learning journey).

 

[danadalis]

I have the exact same issue. What points gap did you end up with?