[djw]

My '76 TR7RV has developed a curious little miss on one cyl like a conga dance. It has a good ol' stock points ignition, the only electrical deviation over the years was a 3-phase alternator 15 years ago thats never been a problem.

The problem:

Doing a little bit of debugging by pulling the plug leads, its apparent that every few seconds the right cyl drops 2 or 3 beats - no spark then normal spark for a dozen, then no spark for 2-3. Continues like this.

Any tips on easy way to isolate the offending component? Or likely suspect? Seems like it would be connections or wire, coil, condenser, (points look ok). Its rideable but the missing makes ya nervous.

I suppose I could start to swap left-to-right coil, condenser, wires one at a time to see which one makes it move (if any).

• If the problem doesn't move then it must be wiring.
• If it does move it's the component.
• If it goes away it's a bad connection somewhere that got fixed fiddling with the wires and spade plugs?

Its always something...

 

[Rathlindri]

First place I'd look:

Coils
Plug leads
Plugs

swaping over one by one to see if misfire "moves" from one cylinder to the other will tell you quickly if one of these components is "duff"

 

[pushrod]

i had a similar situation last year on my 78 tr7v. pulling the plugs and kicking over showed loss of spark on the left side. replaced the plugs and wires but still no good. looked at my coils next and found one original and one replacement... replaced the old coil and shes been good since.

 

[djw]

Both coils are original equipment lucas on mine. 34 years on coils is not too bad.

Out of curiosity, since I will get to fiddle this weekend, is there a readily available original style replacement or is it internet order time if I need a new coils/condenser?

Not interested in changing to electronic ignition, btw.

 

[pushrod]

i picked mine up at the annual virginia british motorcycle club rally. its an emgo. ive seen them on ebbay. originally i bought one on ebay but when it came it was a 6v so watch out for that.

 

[Rathlindri]

Both coils are original equipment lucas on mine. 34 years on coils is not too bad.

Out of curiosity, since I will get to fiddle this weekend, is there a readily available original style replacement or is it internet order time if I need a new coils/condenser?

Not interested in changing to electronic ignition, btw.

I'd bet on a duff coil, you should have no problem getting original spec replacment(s)