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View Full Version : Need help with 86 atc200x chinese carb jetting



RPMRestorations
07-14-2014, 05:44 PM
Hi, I purchased a chinese carb off of ebay and I put it on and it runs like crap. Idles perfectly and runs alright but has a terrible bog past half throttle or maybe a little before, just wondering what I should do about it.

RPMRestorations
07-14-2014, 05:46 PM
Stock exhaust, and airbox lid is on

200x350xtriz250
07-14-2014, 06:33 PM
What was wrong with the stock carb? Problem with the Chinese carbs is you usually don't know what size jets are in there. If the stock carb is toast and if the Chinese carb uses the same style jets as stock, try buying a carb rebuild kit for your bike and rebuild the Chinese are to stock specs and see if that works. If it doesn't, at least you have a starting point for jetting changes, not just a shot in the dark.

RPMRestorations
07-14-2014, 07:52 PM
Yeah, I tried that already.. Im just going to buy new jets for it and go from there. But would it be a main jet or what? Changing the needle clip didn't help at all

Bren_downe
07-14-2014, 08:45 PM
Clean it! I have never used one of these carbs but heard they still have some casting sand left in them when they arrive. Maybe some is stuck in your needle jet.

RPMRestorations
07-14-2014, 09:18 PM
Had it apart already, was spotless. Just dont know which jet to change and if its running too rich or too lean! Ill have to check the plug

200x350xtriz250
07-16-2014, 07:01 PM
Had it apart already, was spotless. Just dont know which jet to change and if its running too rich or too lean! Ill have to check the plug

I am no expert here but it sounds to me like your needle &/or main are too rich. It would help to know where you are at now but try putting the needle clip in the highest slot - closest to the end. What main do you have in there? If the Chinese carb uses the same jets as stock, try the needle & the main that came with the rebuild kit. Main should be around 110.

Here is a good thread with loads of info:
http://www.3wheelerworld.com/showthread.php/55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory

RPMRestorations
07-18-2014, 09:21 PM
The main jet is too big, I tried moving the needle already and it didn't do anything...

newby200x
07-21-2014, 12:06 PM
My 87 had a Chinese carb on it when I first got it.. the main jet was way too small, the motor would just bog and die when you punched it. Ended up buying a few different size mains for it, I think I ended up putting a 115 or 120 in it, solved all the issues.

cap
07-21-2014, 01:20 PM
Does it bog with the air box lid off? I had a bees nest once in air intake tube that went to the air box.

RPMRestorations
07-22-2014, 10:10 PM
It bogs with and without the airbox lid on.. not sure if the main is too big or too small

newby200x
07-23-2014, 07:37 AM
If it bogs when you hit full throttle, hit the choke to see if it brings itself back up. If it does, it most likely means your too lean and need a bigger main jet.

RPMRestorations
07-27-2014, 08:21 PM
it runs normal with the choke but it doesnt have full power