eratic ignition fault with 850 GT loop

[ray bear]

I occasionally read threads here about people that are having difficulty finding ignition faults, Have been helping a friend with erratic behaviour with his 850GT and done all the usuals such as condenser, coils, plugs caps rotors etc to no avail but this morning disconnected the tacho wire from the coil and Bingo  all good, the tach worked well but obviously some thing astray inside so hope this may help others from tearing what's left of their hair out. Incidentally when we replaced the condenser it run well for a little while then played up again but may have just been a coincidence Ray

[guzzisteve]

I had one that was going around w/issue, I never thought of that wire. I got rid of points & condenser and put in a lectronic ignition & that fixed it. Never thought of the tach being the issue. GOOD Catch.

[bigbikerrick]

These ignition issues can really be difficult to sort at times. Good find!
Rick.

[Don G]

The first thing I do when having ignition problems is reach under the dash and pull the wire off of the tach to see if it cheers up. DonG

[John A]

I remember that it was not uncommon for the electronic tach to make ignition problems on a loop. I don’t remember what made it happen but I think it was the first sign of a failing tach.