Important: All appropriate safety equipment and gear must be used during the installation of this or any other ProCycle product including any time you work on a vehicle. ProCycle accepts no responsibility for injuries or damage incurred during the installation of any products.
Be safe – no smoking or open flame. Don’t get gasoline on your skin. Wear eye protection. Use ventilation to avoid buildup of explosive fumes.
From the factory, your TW most likely came with a #126 Main Jet and a #31 Pilot Jet. Yamaha has now discontinued many of the factory style jets for the TK carburetors. We have found an aftermarket Main Jet that fits the TK carb, but the numbering sequence is not the same as the Yamaha jets. Main Jet size numbers you find on the internet will not be the same as the jets we supply.
Each motorcycle can run differently depending on many factors, this is why this jet kit contains more than the jets that we recommend. If you have made changes to your engine, exhaust, or intake you might require different jetting. Also, if you live at higher elevations you may also require different jetting. Our recommendations are a good starting point. Use the jet combination that makes your bike run the best.
- #34 pilot jet
- #115, #120, #125, #130, #135 and #140 main jets
- 6 shims
We highly recommend having a service manual on hand for carburetor removal and installation details.
- Drain the fuel from carburetor and remove the carburetor from the bike.
- Replace the jets with the recommended configuration in the tuning section as a starting point.
Evaluate all adjustments only with the motor fully warmed up (after at least 5-10 miles of spirited riding).
Idle fuel mixture:
Turn the idle mixture screw inwards (clockwise) until the idle speed starts to drop or become slightly rough. Screw the mixture screw out (counter-clockwise) until the idle just smooths out.
We recommend installing the #34 pilot jet.
We recommend installing the #125 main jet to start.
To test the main jet selections run the bike at wide open throttle in 4th gear on a level road. When the bike is pulling cleanly at a good high RPM & wide-open throttle slowly back off on the throttle to about 7/8 throttle. If the bike picks up speed or power as you slightly back off the throttle then you are running too lean on the main jet. If the bike only slows down slightly then your main jet selection is close. If it is too rich the exhaust note may sound flat as the motor revs out. If it is significantly too rich it may misfire as the revs climb.
One shim under your Needle Clip is a good starting point and will work well for most bikes. To go one step richer at mid-range throttle, add a shim. Conversely to set it one step leaner remove a shim.
The needle clip should be set the highest (leanest setting) that still provides smooth steady speed engine operation and good throttle response.