What about temp readings on the exhaust?

I would say #1 has a black spark plug.

 

Will check that Friday. Plugs have less than 1500 miles on them, you think it's a weak spark? No noticeable missing.

 

maybe running a tad too rich on #1. I have been wrong before.

 

this may explains my problem. I've got spark on 3 & 4. I know this becuase i've shocked myself a few times lol. I know it's got gas because the plugs are wet. My carbs were tuned by rickomatic so I know those are golden. But maybe I adjusted the 3 & 4 too rich. Would that cause a misfire?

 

Well, ... when you left we weren't exactly dialed in. There were some snags we hadn't worked-out quite yet.

What was troubling me was why the 4-Hole would fire the Colortune Plug and not Fire the Spark Plug.
That got me to thinking it was a Ignition related issue related to the Coil.

The 1-4 Coil Ohm'd-out in a funny sort-of way. The Primary's were giving me a Zero or a "Shaky" 2.0 ... intermittently. The Plug Wires were good right on 11,000 steady.

1,2 and 3 were hitting. But, all of those three were still Lean.
I had hoped you'd bring them to where they'd be colorized by monitoring the Plugs and tweaking.

But, now that the 3-Hole isn't firing I'm not too sure what the deal is.
I think the odds of BOTH Coils being bad on one side are two low to blame the Coils.

I'm going to go over to the Yamaha Dealership and take a close look at the Ignition Wiring Schematic for the Seca 750 and see it there's any connection to the Instrument Panel displaying the Warning and a possible Ignition Circuit fault that we don't know about.

 

Ok I have the time and the lazer temp gun, I need guide lines.

We do tune with fans running , right?

And this should be done with a warmed up motor, right?

And it's a given that all this will tell you is uniformity of exhaust temp across the cylinders. Basicly still have to use plugs to get color uniformity, equaling proper air/fuel mixture

And my bike is not dialed in but would love to establish a range for temp on exhaust. and just maybe I will get it dialed in, in the process.

And this almost has to vary due to different exhaust systems and to some degree tuning on any given bike. ie. some like it a little rich some like it a little lean
Because I can say up front my 1 & 4 are running hotter than 2 & 3

 

this is what i've been doing because i have a problem with cylinder 3 and 4 not firing. Rather than touching the pipes or pulling plugs to figure out which one is missing I can just shoot a beam on it and get confirmation right away.

 

just tried this for grins (so many toys at work, eh?). but i couldn't get a consistent reading off any of the pipes - i think the gun's "cone" changes too much with distance. i also think 2 and 3 (on a properly tuned engine) should still read hotter just because they're in the middle.

 

I've been playing around with this as well.

On my GPz, which has black headers, I get good readings. These readings vary considerably from pipe to pipe, but I know the bike isn't running right, so this is to be expected.

On the SECA, which is running well, and the plugs show it, I can't get good readings. The SECA has chromed pipes. I noticed also that on other reflective surfaces, like the clutch cover, I don't get a reasonable temp reading (way too low), but on matte surfaces, like the block or head, accuracy seems good.

 

i went out and measured mine pipe temps today. After reading rickcomatic's carb tutorial, i was a little alarmed to find that my pilot screws were very different from each other. like ranging form 1.25 to almost 5 turns. Not surprisingly i'm getting some odd pipe temperatures too. For the most part my bike seems to be running rich (the familiar acceleration lag, smell of unburned gas, and an occasional backfire after i've been riding around for over 10 minutes.

These were exhaust pipe temperatures taken at the first bend. I used the temp sensor on a craftsman multimeter 82337. No lasering or anything here. i physically held the temp sensor to each of the pipes. temps in fahrenheit.
1)265 deg
2)164 deg
3)204 deg
4)328 deg

What's the temp range of a properly tuned bike? I feel like 328 deg indicates lean, but where should it be? 250? 300?

 

Look at the Plugs.
(A ColorTune Plug would put you within Fine Tuning Range very quickly.)

But, without one ... look at the Plugs.
Adjust the Mixture to achieve a dark, tan color on the Ceramic surrounding the Electrode.

Once you get close to what you want.
The adjustment becomes a TWEAK
Not a Turn.
Not a Half-a-turn.
Not a Quarter-turn.
A Tweak ... you can go from too Rich to Perfecto ... within the width of a Nickel.
(Or less)

 

I think that this is a great way to diagnose a "cold cylinder", But I wouldn't use it as a method to tune the carbs. If you find one cylinder to be off, and decided to adjust the pilot screw to correct it, Wouldn't that throw off the balance and require a tune anyways.

Just my thought, does that sound right.
I really can't judge though, my neighbor tuned my bike by ear. Not sure if he has it right or not, but it stats and it runs and it doesn't give me any fits, so I am afraid to mess with it.

 

Nice necro bro

 

Rickomatic,
I wasn't aware the screws were that sensitive. Mine are 3 to 3-1/2 turns out now. You say tweeking them that little bit makes a difference? Looks like I will need to go out and tweek my screws today!