Carb tweakin, am i crazy

K guys, i'll describe what i'm doing and seeing and you let me know if i'm on the ball or nuts hahah.

K so at 3 turns out on the mixture screw, i have white plugs, but it runs really good. At 4 turns out, i get a nice tan colour on the plugs, BUT, if i'm idling when warm, and crack open the throttle and let it snap closed real quick, the engine stumbles down and almost dies, then comes back up to normal idle. At 5k rpms on the highway she runs fine.

I'm thinkin my jets may be partially clogged? cause i have to crank the mixture to get a nice colour on the plugs after a highway ride, but it's too rich when idling (hence the stumble at idle when i crack her open)

Thoughts?

 

Probe the entire "Intake Related" area for Air Leaks.
Manifolds, Manifold Clamps, Carb Throttle Hinge areas (all 4)!

I don't think the Pilot Mixtures should need that much tweaking.
Try probing the whole system with Propane Gas, first.'
If you don't find a leak that the Propane detects, try Carb Cleaner.

Be careful using the Carb Cleaner.
It's not a dangerous as Starting Fluid, but it DOES have a pretty low FLASH point.

 

I'll do that tomorrow and report back.

I have run a tank of gas with seafoam through it as well, it was a bit of a strong concentration as well, just for complete information.

 

Just so i'm clear, Rick, should i only probe the path AFTER and including the throttle shafts, or probe straight from air box to cylinder head?

Thanx!

 

Start at where the Manifolds are attached to the Head
Then, the surfaces of the Manifolds
Hose Clamps next
Throttle Shaft Seals
Airbox connections to Carb Horns

That's the sequence.

 

Ran the propane all down and up the carb line from head, nothin, so i think i'm pretty well sealed

I may have to check float level, that's gunna be a pain lol. I'm thinkin it may be this, cause when i really crank her up to 8-9k rpm, the power isn't smooth, and it seems to stumble.

I might just let it go until winter too, then i'll have the tools, and time to do it right.

 

fwiw ... I pulled my hair out before getting my 82 XJ650J running right.
I bought it from someone who let untreated fuel sit for a year or more.
Would not run past a rough idle.

Cleaned the carbs twice and bought a few new jets.
The second cleaning I had the guts to totally take the 4 carbs apart ... mixtures screws and all comes out and cleaned all the passages.

The tool that really made the difference is the colortune plug.
That tool lets you see the color of your spark ...only then could I dial those mixture screws in properly. She has run great ever since.

I don't have the "ear" to get 4 carbs synch'd up right.
Oh and of course you need a synch tool.

I wish you luck.
-Greg