Jetting - What makes a 2 stroke stall after chopping the throttle

Johndeere506
LT50, un restricted. Did all the recommended sizes that seems universally accepted online. 70 main. Clip is in lowest position. Wide open hesitates a while feeling a little rich, but then cleans up, its fine. However, then sometimes when you chop the throttle it will slowly die, UNLESS you blip the throttle. .
Its actually better w the leaner pilot, which shouldnt be that way unrestricted. Ive messed w the air screw a ton and am at 1 1/4 out.
Any suggestions?
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chaseodc
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chaseodc 5/13/2020 8:11pm
5/13/2020 8:11pm
By unrestricted you're saying the washer has been removed from the headpipe?
CPR
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CPR 5/14/2020 4:02am
5/14/2020 4:02am
Have you tried moving the clip up one and then adjusting the pilot and screw?

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JeremyK
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JeremyK 5/14/2020 4:47am
5/14/2020 4:47am
Have you started with a new plug so it's easier to remove and read it ?
Johndeere506 5/14/2020 6:16am
5/14/2020 6:16am
chaseodc wrote:
By unrestricted you're saying the washer has been removed from the headpipe?
This one only had the intake washer still in place. Removed and rejetted after removing it. now Im here...
Johndeere506 5/14/2020 6:18am
5/14/2020 6:18am
racinstation wrote:
Pilot is too rich.
I dont think so, its the same pilot now as before the restrictor removed.It didnt have this stalling issue before
.
Johndeere506 5/14/2020 6:23am
5/14/2020 6:23am
CPR wrote:
Have you tried moving the clip up one and then adjusting the pilot and screw?
Yes, it felt too lean mostly, so it dropped the clip and thats how i got here. Ive been messing w the air screw at every step to try and find the optimal setting.
Johndeere506 5/14/2020 7:00pm
5/14/2020 7:00pm
I found the problem. I was thinking all day about air leaks and crank seals or leaking from the 2 other sources like capped inlet vacuum line and oil injection. Nothing was making sense.

Anyway, it was easy, on the top of the carb when the cable goes in, there is a rubber boot that seals the sloppy gap between the cable housing and the carb top. It wasnt seated, at all, so i assume it was leaking air. Went back to the original pilot and its good to go now. Seems chopping the throttle with lots of airflow at higher RPM was really the scenario it took to suck air after chopping the throttle and then pull though the small gap without the boot.

Ive jetted many carbs back in the day but this was a little confusing. Im glad i found it, hope it helps someone.
2
Underground 5/14/2020 7:42pm
5/14/2020 7:42pm
Rich idle mixtures(idle screw/pilot/slide cut away) cause the revs to drop below idle on return.
Lean idle mixtures cause the revs to stay up before settling.
Can usually be sorted with the air or fuel screw depending on the type your carb has. If you need to go further than a turn different from standard you need to rejet.
Your's sounds rich. Just because you deristrict or modify something, doesn't always mean you need to go bigger on jets.
It's all got to do with the draw through the carby and the heat/burn in your combustion chamber at those revs/throttle opening/load.

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