Open choke causes bog down. why?

[TT540]

This is a GX270. With the engine warm, I can put the choke at about 75% open and the idle is ~1500RPM. If I push the choke to 100% open, the engines idles down to about 800RPM and struggle to keep running, but does run for a while.

What should my next step be?

It's a stock setup. Vven the valve cover breather tube is still installed. I just recently went through the carb and cleaned it all. fresh gas and what not.

 

[mckutzy]

Has the carb insulator plate being damaged??

 

[TT540]

I will check. So you think there is too much air getting into the engine AFTER the carb'? I will go at it from that perspective and see what I can figure out. MAybe even spray some starter fluid around the mount area.

 

[chevyboy]

I had a similar issue recently. As soon as I took the choke off, the engine would bog down and shut off. Too much air basicly. Either a leak like the other guy suggested or not enough gas. I cleaned my carb 3 times with no luck, and couldn't find a leak anywhere. Someone on here suggested I clean the small holes in the e tube with some tiny files. I used carb cleaner and compressed air, but those micro files did the trick. Happy hunting.

 

[anickode]

I had a similar issue recently. As soon as I took the choke off, the engine would bog down and shut off. Too much air basicly. Either a leak like the other guy suggested or not enough gas. I cleaned my carb 3 times with no luck, and couldn't find a leak anywhere. Someone on here suggested I clean the small holes in the e tube with some tiny files. I used carb cleaner and compressed air, but those micro files did the trick. Happy hunting.

A set of tip cleaners for oxyacetylene torches is perfect for stuff like that. And cheap.

 

[anderkart]

Make sure your carburetor insulator plate is installed in the correct orientation, it can't work correctly and make a seal if its been installed backwards or upside down.

 

[TT540]

Did not try to start it today due to weather, but partially took it apart and the plate between the carb and head has not moved it's whole life. What is the purpose of the air opening and vein that runs up into the plate? The opening is on the bottom of the plate looks like a ram air snorkle scoop. haha.

I did not clean the emulsion tube before other than to spray cleaner down in it and use an air nozzle on it. But if it being clogged/dirty was the case, how come the kart can go ~15MPH at 70% choke and full throttle? ...yet it cannot pull enough fuel to idle?


I found the files you both mentioned:
Torch files:
https://smile.amazon.com/Forney-861...r=8-4&keywords=oxyacetylene+torch+tip+cleaner

Micro files:
https://smile.amazon.com/6pc-Ultra-...F8&qid=1516659833&sr=8-6&keywords=micro+files

Perhaps my idle circuit is to blame and my high idle works at partial choke because it bypasses the slow idle circuit and runs rich. But when I put it to full open choke, the idle circuit comes into play and cannot supply fuel, so it stumbles and dies.

 

[Noseoil]

Idle jet is plugged. Take it out & clean it with a fine wire.

 

[TT540]

+3 internets for Noseoil. That is one tiny hole!

Idles like a champ now.