Coleman ct200u running rich with rough idle through handlebars

[THafeez]

Hey everyone,

It's been a while since I've posted. I got a deal on a Coleman ct200u mini bike at Sams Club last Saturday for 400 bucks plus tax. Problem is I'm getting a lot of black smoke coming off the exhaust and on to the mud guard which means the carb is running rich? New to carb engines/small engines as it is. I'm also getting vibration through the handlebars at idle and tightened everything down. Almost makes it painful to sit at idle. I called Coleman and they said I'd have to bring it to one of their shops, but I drive a two door solara and this things too big! Moving out to the jersey countryside (yes they exist) really has me yearning for a pick up (or trailer hitch).

I took it out for an italian tune up, but it didn't make the problem go away.. maybe the plug is fouled?

FYI carburetor is not adjustable and the idle screw doesn't exist, can't back out the jets either (thanks EPA) they also welded the throttle adjustment screw since people were taking them out to raise the rpms on these things.

It's a fun little bike with a honda gx200 clone Hisun engine. running rotella 10W40 in it.
Attached a picture too!

 

[Linctex]

This may be a dumb question..... but is the choke lever "off"?

 

[THafeez]

yes, it's off. cold or hot, vibration doesn't go away.

 

[ctechbob]

You might be able to Ebay an adjustable carb for not a lot of money that would let you adjust the thing. Sounds like the jetting is off.

 

[Nukeman7]

Just take it back to Sam's Club for an exchange. They have a 90 day return/refund policy and have extended it due to the holiday sales season.

 

[jeepman3071]

I would first try taking the carb off and cleaning it. It sounds like it is running rich, and a passage could be plugged up in the carburetor. I've seen this more than once on a brand new machine.

If that doesn't work, you can often find brand new carbs for under $20 on ebay for those engines.

Also, try swapping the plug with an NGK BP5ES spark plug. Whenever I repower something with a Chinese Honda clone, I swap out the plug with one of these and it usually runs slightly better than the no-name plug that is in there.

That looks like a really cool little bike!

 

[FastLane]

I own one. They all vibrate at idle. Speed up the idle with the adjustment up by the grip throttle. NGK BPR6ES is the plug I use. I run Mobil 1 10W30 with no issues. Its not running rich. They all do that. Just wipe it off once in a while. They are fun toys. Im going to buy another in the spring. My wife steals mine all the time.

 

[THafeez]

Is it possible that running seafoam through the engine will help? I don't want to inadvertently break something on it.

Fastlane, I'll adjust the idle as well. Pretty easy to do with this engine

 

[JTK]

If it's indeed running rich, I'd still pull the air cleaner, look into the carb and verify the choke is operating as it should. I've seen goofy things happen with these carbs like the choke plate coming partially dislodged and block airflow.

Any jetting issues I've have resulted in a very lean running engine.

It's important to swap out that OEM sparkplug as well as was mentioned above.

 

[Marc Hufnagel]

I took a dremel to my throttle stop screw on my BT200X Then put a ziptie on the governor spring to limit it. Different machine.