Triumphrat

Chief601 · 05-19-2009, 10:01 AM

I recently purchased a 1970 T120. After cleaning it up after its long slumber, it fired up but it's running rather rough. Giving it a close inspection, I noticed that the coils discharge into the spark plugs on the opposite side of the bike (left coil fires right plug, and visa versa). I checked the manuals for some reference here, but can't find any. Is this correct wiring, or did someone cross the plug wires? One would think the left coil would fire the left plug, just for simplicity's sake. Any advice would be appreciated.

GrandPaulZ · 05-19-2009, 10:39 AM

If it is an electronic ignition, it fires both plugs every time, so it doesn't matter.

If points ignition, you only need to swap primary trigger wires from the points, then swap the hi tension leads to thier proper sides.

Chief601 · 05-19-2009, 01:56 PM

Thanks. I'll check the trigger wire colors, but I take it that the spark plugs wires should not cross to the opposite side of the bike after they leaves the coil? Maybe just switching them to their own side will work.

thirdbike · 05-19-2009, 05:27 PM

"Switching" will not address the rough running you describe although the plug wires are not supposed to cross. You don't indicate if you have points or an electronic conversion.
Paul is right. If you have a Boyer switch away at will. If points, the wiring has to be crossed somewhere. Yellow/black should remain yellow/black and white/black remains... If you do have points, you'd be wise to replace these along with the condensers considering the long slumber. In all probability, this still may not solve the rough running but at least you can now problem solve down the list.

Chief601 · 05-20-2009, 08:16 AM

I didn't mean to imply that I thought switching the crossed wires would solve my rough idle problem. I just happened to notice (and start the head-scratching) when I was giving the bike a close inspection prior to my problem-solving steps.

The bike still has points, which I cleaned and gapped prior to starting the bike. One last question though, and then I'll go back to the garage. My wiring diagrams do not label the coils left or right, so I have no way of knowing if the wires leading into the coils have been switched. Could you tell me which color (yel/blk or wht/blk) should go to which coil.

Much thanks!

thirdbike · 05-20-2009, 11:37 AM

It doesn't matter which is which although only one schematic identified black/yellow as the right side. Good luck

Chief601 · 05-20-2009, 01:27 PM

Right you are, sir. I just found a note on a diagram in my Haynes manual detailing the contact breaker that states, "the left contact (blk/yel) fires the right cylinder."

Onwards...