Mikuni CV BS34 lean but rich?

Thus spake Zarathustra.

My 2 cents;
You probably have, but Compression test? If not running on all this needs checking, along with valve clearances.
Pods = PITA to set up on CV carbs but can be done. Better to fit the stock air-box.
But stock pilots and needle jet settings with pods will be too lean. Put in some 40 or 45 pilots, shim up those needle jets, 127 mains might be pretty close. Use the clear tube method to check the fuel level in the carbs not just a float height measurement.
Again as everyone mentioned, it has to run on all 4 with the Ignition and engine in good working condition before messing with carbs.
Stock air-box would most likely need no further re-jetting, Pods will, your choice.

Don't screw with the pilot jets!!!! That is the biggest mistake people make with these carbs. Keep them stock.

jga2z wrote: I rechecked the coils, 2.6-2.7 ohms primary 12.3K ohms secondary, batt voltage @coils, will jump 5/16-3/8 air gap on all 4.
Doesn't this seem like it should work?

Am I beating a dead horse?
To move on from ignition I need this question resolved.
Clymers says coil specs are 1.8-2.8 pri, 10.4K-15.6K sec, and I saw a post which said air gap test should be about 1 cm.
Can I move on to fuel/carbs?

I would say so. At this point just leave the ignition alone.

jga2z wrote:

I rechecked the coils, 2.6-2.7 ohms primary 12.3K ohms secondary, batt voltage @coils, will jump 5/16-3/8 air gap on all 4.
Doesn't this seem like it should work?

Am I beating a dead horse?
To move on from ignition I need this question resolved.
Clymers says coil specs are 1.8-2.8 pri, 10.4K-15.6K sec, and I saw a post which said air gap test should be about 1 cm.
Can I move on to fuel/carbs?

Visually observed fat blue sparks across the plug tips likely evidences acceptable ignition. Am thinking the ignition timing isn't owner adjustable on this bike. However, may verify proper function of the timing advancer by watching the timing marks under a strobe-type timing light to confirm it's moving quickly back and forth as rpm is varied by blipping the throttle. The advancer might require lubing or both cleaning and lubing.

Should perform a compression test AND assure all valve clearances are within specs BEFORE addressing the carbs.

Good Fortune!

I definitely agree about making sure that your valves are adjusted properly. Your cam may be riding a bucket and therefore you have an open valve. Check the compression of all cylinders. What ever it is in one it should be in all four +/- a hair. (red preferably, they're the thinnest ):laugh:

I don't claim to be a 4 stroke pro tech but i have been wrenching at the "amatuer" level for the past 24 years and along the way I've tought myself a few good lessons when I develop an issue.

1)ALWAYS perform simple tests FIRST ! My #1 test is compression. You need all 4 cyl around 125 psi min and all within 10% of each other. You would be amazed at how many people think they have ignition issues when they really have a "bad hole" (low compression in one cyl)

2) Try to isolate weather you have an ignition problem or a fuel problem. Don't attempt to diagnose and or "guess repair" both systems at once.

No doubt running issues on older bikes can be a frustrating PIA, and I have had my share of ghost PIA issues, but my point is simply crack a beer, take a breath and try to systematically approach each diagnostic test.

OK the compression test shows #1 150, #2 155, #3 155, #4 150. on a cold (wet) engine
That looks pretty good.
I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now.

Back to the carbs?

jga2z wrote: OK the compression test shows #1 150, #2 155, #3 155, #4 150. on a cold (wet) engine
That looks pretty good.
I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now.

Back to the carbs?

Compression is good. Back to carbs. You comment you need to keep the choke on for the engine to run, and you also comment #3 and #4 seem to not be firing. Kawis fire 1-4 and 2-3 so with this i'm tossing out the idea of a bad coil. If you had say 1-4 cylinders not firing ,now that a good sign the approiate coil is suspect. I am really thinking you have a #3 and #4 fuel starvation issue. Simple test first crack the bowl drain for carbs 3 and 4, make sure you have a stead flow of fuel out the drain hose. It really sounds to me like you have a plugged #3 and #4 pilot jet circut...

It sounds as though your problem is fuel related. You may have Vacuum leaks around your intake manifolds, or dirty carb circuits. While some may disagree with a larger pilot jet, I can tell you I have the BS-34 Carbs with 40 pilots. They run much better and start easier than the 37.5's. All stock on 1 bike, 82 1100, and a 4-1 Vance & Hines on a 82 1000. Altitude of 6K plus. Never shows any rich conditions, great plug readings and the 1000 got 50 mpg over 3600mi trip. That's loaded with Vetter fairing and bags. Strange that every other thread recommends jetting increase through the range of the carbs with pods.
Have you properly set your fuel levels in your carbs with the clear tube method?
What about Sync, do it on the bench first using a round paper clip or wire for a gauge. Set all 4 butterflies the same. Turn your pilot screws the same # of turns out, like 1 1/2 for starters. Get it to run on all four, then a running dynamic sync once up to temp. You can make a Manometer if you don't have one, or maybe borrow one.
What does the plugs look like, wet on the cylinders that are not running, or dry?

jga2z wrote: ...I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now....

Valve clearances are supposed to be measured when the engine is cold.
Because the clearance diminishes as the engine warms and attains normal operating temperature. The specs recognize and allow for this attribute.

Good compression on a cold engine may result when valves are just barely closed with minimal clearance. Then the compression suffers when the engine gets warmer, because the gap disappears and the valve fails to seal as it can't fully close.

Consider, even perfect carbs can't compensate for deficiencies in the other components. For instance, with leaking valves due to insufficient clearance, it's imo a waste of effort to address carb tuning.

Good Fortune!