Turns over use choke get backfire.

[ShadyBrady]

I have a 78 xs 650. New to motorcycles. I've been trying to get it running with just a makeshift gas tank. I have good spark and gas but it just cranks over. Add a lil choke and loud backfire from both sides. Any help?

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[scabber]

Welcome to the site. The timing might be off. 78 had points check point gap. A google search top left hand top corner of the page will give you how to.

 

[ShadyBrady]

Thanx. I did the timing and cleaned the points already. Any other ideas? I can do it again.


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[XSLeo]

Yes, the 78 has points, it sounds like at some point the wires from the points to the coils got reversed.
An easy test is to just swap the plug wires left to right.
If this makes it run, trace the wires up from the points. Where these wires plug into the wires to the coils. Just reverse them.
The upper set of points fires the right side coil. The lower the left.
Leo

 

[ShadyBrady]

K. I'll try that. Working right now but let you know. Thanx!

 

[scabber]

If timing and points set Leo solution should fix it.