Sorry... 74 TX650A
The bike has points
Thank you
With Points I would do like this.
I am not exactly sure about 1974 but on my 1980
Stock there are 2 Coils under the thank ..where the cable goes out to the spark plug caps.
I would put the spark plug caps on both
Please inspect that the one with problems looks OK at the Bottom .No dirt or so .
I use a bit of Copper grease to ensure that there are contact.
And that the cap is screwed on the cable properly..
And check that the connection at the top of the spark Plug is OK not loose
Then I would take the cable and Plug ( going from the coil) on the right side and move to the left side
And the cable on the left side with spark plug to the Right side..
Trying to start again .
At this point in time I Suspect a defect spark Plug cap.Or bad connection.
In that case the problem is now at the left side.
If so make the same test as in the first place.
After that test I would move over the right side spark Plug to the left side and the left to right.
Please try this then we reevaluate Paying attention to the spark plug cap status that are perhaps old cracked or so
If you have a spare spark plug cap One way forward is to put it on directly and test.
Or can get one or two close By
Not moving anything else.
Please report success or failure or what else happens