Tao Tao TBR7 Carburetor Replacement and Tune Up Part 1

 

The Tao Tao TBR7 is one of the cheapest motorcycles you can buy brand new. With shipping I paid $1600.00 bucks for my motorcycle. They are very "customizable", and they run fairly well. 

The TBR7 is made in China and that does mean a few things must be tuned, and or modified. The main thing that needs replacing or modifying is the carburetor. The stock carburetor is sealed, unless you cut slots in the unit. You can not take it apart, and the stock carburetor comes with a small main jet that bogs and sputters when you give it 3/4 to full throttle. 

What this means is out of the box the bike will idle ok but when riding the bike the engine will bog or sputter when you lay into the upper end of the throttle. This is due to the main fuel jet that is used at the factory. The main fuel jet is a generic one that is not appropriate for you elevation and geographical location. Not to mention when you customize your air filter and or exhaust system it will change the needs of your main fuel jet. The diagram shows a cut away carburetor. The main jet is located at the bottom of the carburetor. Where it can suck up the most fuel. 

How does the Throttle Work:

When you turn your throttle from 0 to full, there are 5 phases that you run the fuel through. Each phase adds more fuel to the fuel already added by the previous jets.

At the no throttle position fuel is passing through your "Pilot Jet". This idling. You can use the idle adjust screw for rpms and your fuel mixture screw for tuning the smoothness of the idle. The throttle valve is at work letting air in with the fuel. That's the small cut away area of your slide. 

The next step is 1/4 throttle. This is where you apply a little fuel to let our the clutch or slowly roll along. Then as you roll on more throttle you start sucking gas through your needle jet and then the space made by the needle lifting up itself. as you get to three quarters throttle your carb is taking fuel from your maid jet and adding to the mix. 

So as you start you take fuel from one source and keep adding more sources to it to build full RPM's. The carburetor is small but there is a lot going on, and can seem very very complicated at first. What this all means is if it the carburetor dont run well at idle then you need to pick the right pilot jet, if it dont run well from a quarter to 3 quarters you need to adjust your needle jet and Jet needle, and it it does not run well at 3/4 to full throttle you need to adjust your main fuel jet. 

It is imperative you only work on one phase at a time! Otherwise you creating 5 or 6 changes and results each time never being consistent on adjustments. Below is a video done by Jay So Lo of Youtube.com. I figure why make another carburetor video when there are 3 or 4 that are already well done. Plus these guys really know there stuff!

Please See Part 2 for further explanation!