Enrichment issue


400J Butterface
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Seattle, WA
What do you all think?

Bike requires full enrichment to start, but will only stay firing well for a few seconds before I have to back the switch down a bit. As the bike warms up, I have to slowly lower the switch to get the rpm's up. The more choke, the harder it is for the bike to run.

I believe it is an issue with the right side because there is little exhaust during warm up compared to the left. When the exhaust is even, it is when the bike is running smoothly and the rpm's are climbing. (This only happens after 7min or so of warm up with the enrichment switch down to 1/3.) It appears that as I lower the switch, the right side is having an easier time firing and therefore is able to keep up a bit.

It is important to note that when I find the balance with the switch where the engine revs at its highest, that mark is only 1500 rpm's, 2000 when warm.

Once warm and the swith is off, the bike appears to run smoothly and evenly. This is only an issue with the enrichment...Maybe.

The right plug has been showing more fowl than the left for some time now. Valves are perfect. Carbs are perfect. Both coils tested the same when off of the bike. That could have changes since then.

I Believe that the right side is not firing as strongly as the left. What do you guys think?

How do I test this issue?

Thanks in advance.
I don't think I fully grasp the enrichment issue. When you pull on the choke the bike is supposed to rev high for a bit (to get it warmed up) you may then proceed to reduce the choke until its completely off. As for the second part I would definitely check your compression as maybe the left spark plug is oil fowled (not gas fowled) usually caused by worn piston rings or valve guides. I would also check your timing as well as sync your carbs which seems to solve a lot of problems. Oh and last thing is see you wrote "carbs are perfect" which is usually a sign that you have to clean your carbs:wink2:
Normally the extra fuel while using full "choke" will cause the rpms to jump quite high (like 4,000 or so). I think you're experiencing "bogging" which occurs when your air/fuel mixture is very rich (rpms will tend to drop and the bike won't want to rev up).

You said the carbs are perfect, but humor me.

Have you balanced the carbs?
What jets are you running and do you have any modifications to intake or exhaust?

Finally, if there is no obvious error and the motorcycle runs fine otherwise consider forgetting the issue altogether. I do recommend tuning the motorcycle for some kind of arbitrarily desired behavior while using "choke" if there are no other issues. If there were other issues I'd dig further, but if it's just while using "choke" forget about it.
Thanks for the reply phate.

To clarify:
The bike requires full choke to start, (typical) but will only hold for a few seconds before the rpms dive and the bike sputters to death. I have to gradually turn the choke DOWN to keep the rpms UP. 2000 is the highest I can balance it between to much choke and not enough.

I've been analyzing this issue for months and it really just seems like the right side doesn't have enough fire for the amount of gas the enrichment lets in. But oil foul. I can buy that. I've suspected bad rings for quite some time; however the compression is within spec; wet and dry tested with little fluctuation.

Carbs are perfect, meaning, they are perfectly balanced because I balance them regularly, any time I make any kind of adjustment anywhere, which is sometimes several times a week. They've been through the dozen cleanings described throughout these threads, boiled, probed, compressed air. Every Single passage is clear. New diaphragms, new pilot screws with o rings, new choke plunger seals, numerous jetting combinations, just installed new manifolds with an extra layer of liquid gasket to be extra sure of leakage. Carbs balanced again and again and again. No real variance each time, I just like to make sure.

I have recently checked the timing which is fine. These are self adjusting bikes but wanted to be sure.

I'm ruminating on the "oil fouled" comment. I have been trying to pin point a light metallic scraping, and honestly, once I was able to get these carbs in top shape with the right jetting, I am able to push redline whereas before I was topping out at 6500 rpm. There is a new stress for this engine, so it wouldn't surprise me about the rings.
Mr Bcware sir, the right plug is fouled. I know we've spoken about this in a previous thread where I was describing having it set to 2 turns out, the left 3 turns out.

I'm intrigued by this oil fouling theory. When I put the new manifolds on, I turned it back to 2 1/2 turns each because I wanted to see how they acted with the possibility of vaccum elimination from the old cracked boots. At 2 1/2, the left is fine and the right is black but not caked, so I may try to adjust it down 1/2 turn.

I really don't think that will be enough to fix this issue though. That is why I am thinking spark strength and now, maybe, oil foulage.
Carbon fouled = too rich (I don't want to assume you know that, and maybe someone else who reads this will learn.)

Oil fouling will also cause blue smoke. Do you have blue smoke (and a horrible smell...)
No smoke:( in-fact, very little of anything visual comes out of that right side. (But I can feel it at least.)

There has been a bad smell lately, but don't connect it to burnt oil from my sense memory. I assumed it was possibly chain lube over-spray that was taking a veeeeeerry long time to burn off of the exhaust.

Do the main jets play any kind of role in the warm up process?
What's your float height set to? Do you have those black floats or the older brass kind?
Have tested the spark is there a difference in color betwen the two sides?A weak spark would be yellowish orange while a strong spark will blueish yellow.How about checking wires and plugs if you suspect a weak spark issue.