Pwk jetting question

Lean bog I call Mooing, good off idle response but then it goes MOOooooooo.

Worth mentioning a float that is set almost empty all the time can also do that.

Rich bog, at least in my experience, farts out black smoke and falls flat on it's face, sometimes it clears up and revs, sometimes it doesn't.

To get an idea where your a/f is, after running the engine normally (drive cycle), shut it down without idling, pull it and take a picture of the plug. (reinstall when engine has cooled)

You want chocolate or tan on the anode and cathode, totally clean or very light grey powder is usually lean, black and powdery usually means rich.


As Nickt919 said, always start rich and work your way leaner.
 
When I'm tuning I like to rev it till I hit the spot in rpms where it starts acting goofy and quickly give more throttle if it clears up and pulls good you know its too rich, if it kills all power and falls on its face you know its lean.
 
When I'm tuning I like to rev it till I hit the spot in rpms where it starts acting goofy and quickly give more throttle if it clears up and pulls good you know its too rich, if it kills all power and falls on its face you know its lean.
Yeah that's what happens, once it's warm. I'll pop it and it'll want to cut out , but if I'm quick enough and snap it past that point it'll rev to the sky.

I have a question to any and all: when my motor warms up , does it suck air and fuel harder than when it's cool. Like the effects of different temps (outside the motor, and inside) creating a harder vacuum. If there is truth to this then I may have a theory, but I don't want to state it too soon and look stupid.
 
if you want to give this a try before swapping jets you could move the clip on the needle 1 more spot down to richen it a little and see what happens.
 
Ok may have discovered something, well I did but I'm not sure if this is the whole story. I checked ally bolts again and they're all tight, including the reed valve. But, the seals on the reed valve were leaking. So I cleaned up the outside real good and I had a tube of jb weld clear 5 minute quick set epoxy and mixed some up and coated every joint on the thing, it doesn't look bad either, and once it's really hard I can sand down the high spots and lumps. Unfortunately I won't be able to to test it until work in the morning, have too many house chores to do 🫤. The bike is always warmed up real good by the time I hit work and has started acting funny about right as I get there, so I'll have a report at 6am CST.
 
Ok here it is: status unchanged. It still starts acting up at around the same time as always. I thought maybe my air filter was too restrictive and therefore acting as a small choke as the motor got hot. I pulled it off and still the same. But I was watching the venturi slide and needle as I would throttle it from idle, and at idle the gap between the bottom of the slide and the carb body is about a quarter of an inch. That seems a little high to me. And as you barely twist the throttle it hits the point of the needle where it starts to taper. I'm thinking maybe if I drop the clip, I could drop the idle setting and then it would be at a point of the needle where the jump in taper wouldn't be too severe. I'm already using the needle with the most gradual taper. It ran way too weird with the last one. Or maybe I need to try the other needle again now that my air mix is right, unless I'll have to adjust again because of the needle.
 
Dropping the main needle (clip towards flat end) will lean out your mixture.

If you have no air leaks (tested by spraying with water or carb cleaner and checking for rpm drop/rise) you need to tune based on sound/feel and your spark plug deposits, not on how the carb looks.

It's worth mentioning that some of these carbs need an air filter restriction to run properly.

Run it normally, but not too hard, shut it off without idling and pull the spark plug, post a picture here.
 
Dropping the main needle (clip towards flat end) will lean out your mixture.

If you have no air leaks (tested by spraying with water or carb cleaner and checking for rpm drop/rise) you need to tune based on sound/feel and your spark plug deposits, not on how the carb looks.

It's worth mentioning that some of these carbs need an air filter restriction to run properly.

Run it normally, but not too hard, shut it off without idling and pull the spark plug, post a picture here.
Ok, that'll be when I take lunch. I'll pull the plug first and clean it up a bit and then post.
 
If it runs fine cold then starts acting up as it heats up.. it’s a good chance there’s an air leak.

I had a case leak do me the same thing. Run fine cold and bad hot. It drove me batty trying to run it down.

It is common for an engine to change the way it runs as it warms up but not so drastic as to indicate bad tune. My engines tend to idle a little higher and not be as spunky cold as running temp but it settles down within a couple minutes of run time.

A small piece of my case center gasket broke and pushed out in the area of the clutch shaft and I didn’t find it until I tore my my engine down and saw where oil was tracking into that area. Spray testing didn’t find it.
I went in circles with jets and needles trying to fix it.

Not saying this is your issue. Point is.. sometimes air leaks are difficult to run down.

If the tune changes drastically after the engine heats up there’s a strong possibility an air leak somewhere that is responsible for this. When the leak shows up the tune goes leaner.

A thing you could try to prove whether it’s an air leak or the carb/reed is put the stock intake and carb back on and see if it responds the same way.
 
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