MIKUNI (CHIKUNI) TUNING PROBLEMS

#1
Hello, My name is mason and i recently purchased a coleman bt200x mini bike

I purchased a mikuni (chikuni) 22mm carburator kit with filter for it and i cant seem to get it tuned correctly......

i have not touched the needle nor have i replaced any jets. I am currently using the stock jets in it and the stock needle setting.

the bike is backfiring really bad. It also doesnt want to idle correctly.... then i noticed i had alot of fuel in my oil.

I am not very knowledgable on carburators... at all....

i currently live in missouri where the elevation is around 460 feet above sea level.

The modification i have already made to the bike are as follows

Governer removed
Torque converter
header and muffler pipe.

i have seen alot of success to these but i cant seem to get it right....

if someone could please help me with my issues i would greatly appreciate it. I am new to all of this as well.
 

DaddyJohn

Well-Known Member
#3
the bike is backfiring really bad. It also doesnt want to idle correctly.... then i noticed i had alot of fuel in my oil.

The modification i have already made to the bike are as follows:
Governor removed
Torque converter
header and muffler pipe.

if someone could please help me with my issues i would greatly appreciate it. I am new to all of this as well.
The fuel in your oil would seem to indicate that your float needle is leaking and the carb is overflowing.
I'd start with checking the condition of the float needle, and also your float height while you're in there.

With regards to your modifications, and this gets repeated a lot, you really need to install a billet rod and flywheel when you remove the governor.
The stock rod isn't made to handle sustained high RPM, and is prone to breaking, which can be catastrophic.
The issue with the flywheel is it can chunk into pieces at high RPM, possibly exposing you to injury.
 
#5
The fuel in your oil would seem to indicate that your float needle is leaking and the carb is overflowing.
I'd start with checking the condition of the float needle, and also your float height while you're in there.

With regards to your modifications, and this gets repeated a lot, you really need to install a billet rod and flywheel when you remove the governor.
The stock rod isn't made to handle sustained high RPM, and is prone to breaking, which can be catastrophic.
The issue with the flywheel is it can chunk into pieces at high RPM, possibly exposing you to injury.
I was planning on doing this as well, I just wanted to get the carb dialed in first!
 
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