Ignition circuit diagnosis.

[5twins]

Sounds like the right cylinder isn't running at idle, or running much slower than the left. Not firing at all would be an ignition problem. Running much slower would be a carb sync problem.

The type D cam chain tensioner you have is the worst of the lot, lol, because it doesn't have a lock nut. Yamaha used it for only a few years then went back to one with a lock nut.

 

[Jan_P]

I am thinking still ignition problems For me it is much simpler finding it there than taking the carburetors out
Has it been running through any heat cycles and getting carburetor float valve moving .
Not having heard it run If there is sparks looking the same at the points Now
I Would try to run a little perhaps tapping the outside of the carburetor with a screwdriver handle
If possible closing the fuel flow and when it stumbles open it again getting the float valve moving.
It sometimes can take a little time before things settle 2 or 3 tanks even

 

[gggGary]

The left side is running a lot hotter than the right side. I can still touch the pipe right out of the head about 3 or 4 min after starting. Any ideas?

Only run at idle or at all operating speeds?
A cylinder needs three things to run; compression, spark, and fuel. Your right is missing at least one.

 

[Kevin Werner]

I have limited experience. My Red Bike ran a very cool cylinder when I got it running decent. My sync was way off. An aside... You can do a remarkable amount of carb cleaning with out removing carbs. Bowls come off and back on in 6 or 7 minutes and add a minute or two clearing passages with spray cleaner. With the spray cleaner straw you can shoot most jets and passages in another minute or so and see the results if the air cleaners are out of the way.

 

[The Phantom]

I have limited experience. My Red Bike ran a very cool cylinder when I got it running decent. My sync was way off. An aside... You can do a remarkable amount of carb cleaning with out removing carbs. Bowls come off and back on in 6 or 7 minutes and add a minute or two clearing passages with spray cleaner. With the spray cleaner straw you can shoot most jets and passages in another minute or so and see the results if the air cleaners are out of the way.

I had the top end apart to replace a broken exhaust valve. I put new rings, honed the cylinders and cleaned the carbs through complete disassembly and parts bath.I didn’t sync the carbs though. I take them off and do a rudimentary sync then reset the valve clearance on that side. Thanks for the info.

 

[Melnic]

Going back to your spark,
One way to divide and conquer is to swap the orange and white wires from the points where they connect to the harness.
With tank removed, the points wires each go to a junction where it has a 2 connection bullet female where the condenser caps connect to each side. White goes to the right coil and orange to left coil. If your getting spark on one side and not the other, swap the white/orange there. If the problem remains on the same side, problem is the coils up to the plug. If the problem switches, its the points.
If its the coils, you can measure resistances. You could have a bad cap, a bad wire, a bad plug etc. Are these resistor plugs or non resistor plugs?
I had a loose cap on another Yamaha as well as a failed Resistor plug for a bike that had resistor caps and the higher resistance kept the spark from happening.

 

[The Phantom]

Going back to your spark,
One way to divide and conquer is to swap the orange and white wires from the points where they connect to the harness.
With tank removed, the points wires each go to a junction where it has a 2 connection bullet female where the condenser caps connect to each side. White goes to the right coil and orange to left coil. If your getting spark on one side and not the other, swap the white/orange there. If the problem remains on the same side, problem is the coils up to the plug. If the problem switches, its the points.
If its the coils, you can measure resistances. You could have a bad cap, a bad wire, a bad plug etc. Are these resistor plugs or non resistor plugs?
I had a loose cap on another Yamaha as well as a failed Resistor plug for a bike that had resistor caps and the higher resistance kept the spark from happening.

This thing came with no spark plug cap on the right side, so I just wrapped the wire lead around the plug terminal. I know it’s getting current, it bit me once when o got too close. New plugs. I don’t know if the spark plugs are resistor or not.

 

[Melnic]

stock bike will have a resistor cap so if you don't have the cap, then you are lacking the resistance that the coil expects. I recommend verifying spark.
post the plug part #
caps are not expensive.

 

[The Phantom]

stock bike will have a resistor cap so if you don't have the cap, then you are lacking the resistance that the coil expects. I recommend verifying spark.
post the plug part #
caps are not expensive.

Ok

 

[The Phantom]

Ok

Plug # Champion N9YC