Right cylinder firing less than left

[Super Dave]

1973 rd350 barn find- sitting 25 years. Seems to have a bottom to mid range stumble. Right side is definitely not firing as much as the left. Checked coils, rectifier, regulator, timing, condenser, and points. All are within spec. Spark plugs seem to be a little sooty, and appear about the same. Carbs have been throughly cleaned, and synced, new float valves installed. Unsure about exhaust, (DG expansion chambers) seems to be smokey upon startup. Will check to make sure they are clear. (Plan to have them hot tanked) Removed the light checker unit, it runs much better without it. (Took a while to figure out thst issue) I've gone through everything ad nauseam.. Can anyone put a little meat on the bone?
Super Dave

[1976RD400C]

Maybe try a compression check. Sooty plugs should be replaced. Voltage reading while running? Spark plug cables ok?

[m in sc]

if the coils are original, change them. they can test ok but not be. also plug wires and caps. 

[Super Dave]

Cylinders still show cross hatching from a very recent bore before storage. Spark plugs are new, but dirtier than normal."Sooty" was the most accurate means to describe plug condition. Have not tested voltage while running, I am assuming the hot lead on coil? (Both coils have resistance within specs) I have access to some original coils, I used CM 11-50's. (It had some funky coils (cracked) mounted on the frame rails) spark plug wires look new, but appear to be automotive (built in plug caps) Thank you both for the input, I'll be back at it after the holidays.

[m in sc]

few things to look at:

charging voltage. its needs to be over 13v over 2k. if not, it can be an issue.

the carbs.. all original brass inside? im assuming so, but if you used a kit and used the supplied slide needles, they are incorrect. also assuming the jet tubes were removed and thoroughly cleaned. if not, can be an issue.

the ignition: use copper core plug wire. If the coils are suspect, i posted a link about using SV650 coils int he tech forum. would recommend.  as far as plugs and caps: since non resistor plugs aren't being made by NGK anymore, economy cycle lists non-resistor caps.

since you're saying BOTH are sooty, its more of a macro issue affecting both.  In MY experience, and i cant explain why, when battery voltage is low, it seems to affect the RH cyl 1st.

good luck w it. you'll def get is sorted.

[Super Dave]

Thank you for your advise. Brass is original, the floats are the closed cell plastic type. Both floats weigh 2 grams. The emulsion tubes were checked, no corrosion. Since the plug wires and caps are suspect,I will replace them, (and the coils) before startup. (Will check the charging circuit then) The battery of course, is new, and well charged before the test ride. I felt that the plugs were dirtier than need be for such a short ride, they appeared a little "damp" (25 pilot/150 main) I didn't really get to row thru the gearbox, as the clutch was slipping. Parts are on order.

[teazer]

May not be relevant to your issue, but unleaded gas tends to leave the plugs looking sooty especially if the bike is not run hard enough to get the plugs up to self cleaning load levels.

[Super Dave]

Update: Installed copper core plug wires and non-resistor caps. Fired bike up, it is now misfiring on the left side instead of the right.(right side is running fine) Rechecked timing, and carb synchronization. I have not replaced the coils. Has anyone out there experienced this type of malady? Any input or information would be appreciated I haven't seen this before. I'm about ready to get some bongos, put on a grass skirt, headdress, and see if I can excise the Gremlins from this bike.

[Super Dave]

Update: There is 13.4 volts going to the battery while bike is running. Replacing Springs on clutch was inadequate, must replace clutch pack. In spite of misfiring, and the clutch slipping,  it feels like the bike is capable of making great power.

[m in sc]

timing wont cause a misfire.. but 50 year old coils will. 

[axldk6]

Update: There is 13.4 volts going to the battery while bike is running. Replacing Springs on clutch was inadequate, must replace clutch pack. In spite of misfiring, and the clutch slipping,  it feels like the bike is capable of making great power.

SD, I've had my bike for 5 ? months now and haven't made it out of the garage yet. But this community on here is great at helping out. And I'm getting close. But what is the light checker unit and was it shorted out and what were the  symptoms if I may ask.

[Super Dave]

It has been taking forever to get my parts in. A light Checker unit is simply a 12 volt light bulb connected to a couple of wires, ending in alligator clips. (It's easy to make one,as I did) The bike seemed to idle fine, but when RPMs were applied, one of the sides would misfire. At first it was just the right side, then later it switched to the left. This was pretty damn confusing. I am still using the same coils, they are stock, but they are not original. In the interim, I discovered that the autolight spark plugs I was using were equivalent to a br-9es. I found the champion equivalent to a b-9es, which is an 805. When I fired the bike up, it seemed to be improved running on the bench. Received the fiber plates for the clutch last night. When I took the clutch apart, I discovered there are no rubber dampeners in between the metal and fiber plates. (7) I am now hesitant to reassemble without these parts. The local Yamaha shop wants $21 a piece, which I think is out of hand. Question: are these rubber Parts in between the plates really necessary? Could the source of the misfire malady been caused by using plugs that were too cold of a heat range? My RD has the DG heads  (which is why I'm using an ES instead of an HS plug) and expansion chambers.

[Super Dave]

A light Checker unit on an 73 rd350 is located in front of the coils, behind the steering head.  There are three wires coming from the dash that plug into it.

[m in sc]

they are not. most people remove them. when you use a FZ600 set of plates they dont even fit anymore. just throw em in the trash.

[Super Dave]

Thanks for the reply. I had no idea that FZ600 fiber plates would fit. They are probably far superior to the aftermarket reproduction ones I had bought. I am anxious to see how the RD will run. What year FZ? Will the metal plates fit as well? (Most likely I will end up replacing the clutch pack)