Adjust on the fly!
TDUBWilly (member of the TW200forum) stated that his Adjustable Pilot Mixture Screw “was born from the hatred of having to carry a cut-down pocket flathead, only to burn your hands while attempting to adjust your pilot mixture screw!”
The TW200 adjustable pilot screw is designed for the 2001+ TK (Teikei) CV carburetors and should work fine on the clone carbs that lots of people run. A few dimensions had to be modified, but he made it work with the OE Teikei and the eBay-special clones. That assumes all clones are made alike, which may not be true. He also has fitments for the 1987 – 2000 TW200’s too!
Purchase 2001+ TW200 Pilot Screw: eBAY: https://www.ebay.com/itm/266975739308
Purchase 1987 – 2000 TW200 Pilot Screw: https://www.ebay.com/itm/266987802606
The custom-designed pilot screw flairs down and outward with a large knurled head that is conveniently located below the carburetor for “on the fly” tool-less adjustment. Even when the engine is at operating temperature, adjusting the pilot screw is easy!
The TW200 Adjustable Pilot Mixture Screw is CNC machined from brass, knurled finger-grip with a flathead slot on the end and an indexing notch on the side to keep track of the settings.
eBAY link to purchase down below.
Installation of the Adjustable Pilot Mixture Screw
For the installation of the pilot screw, I wanted to get my TW200 up in the air to show you what I am doing easily. We will address the bike from the left side of the TDUB, as it is easier to access the carburetor from this side. I removed the seat and the gas tank.
Removing the gas tank allows me to access the throttle cable bracket, which allows me to remove it and give the carburetor more movement.
In the image below, you will see that I have rotated the carburetor over to visually and physically access the bottom. You will loosen the clamps on both sides of the carburetor, where the air inlet and exit tubes hold it.
PAY CLOSE ATTENTION!!!
In the above image, you will see me indicating where the TW200’s stock pilot screw is located with the chopstick pointer. BUT BEFORE YOU DO ANYTHING! You are NOT going to start screwing out or removing the pilot screw!!! WAIT – THINK! We have to determine where the screw is set currently precisely! You want to make this change without changing how the TDUB is presently running.
PAY CLOSE ATTENTION – HOW MANY TURNS!!!
Take your small flat-blade screwdriver and clockwise, YES, CLOCKWISE turn in the pilot screw, COUNTING EACH ROTATION. WRITE IT DOWN! Do whatever you have to do to “reverse repeat” this process when putting the new pilot screws back in!
Making your bike run exactly as it was before starting this process is important! Think of it as your “ground zero!” Typically, your TW200’s carb should be around the 2.5 to 3 clockwise turns in before it stops – bottoming out. BUT COUNT YOUR TURNS! Don’t push hard! You are pressing a small brass needle into the aluminum carburetor housing.
Now you can remove the factory TW200 pilot screw. BUT BE CAREFUL, as on top of the pilot screw is a spring, metal washer, and a rubber gasket! PAY VERY CLOSE ATTENTION!!! DON’T DROP THESE ITEMS!
OH BOY! My pilot screw is a little dirty! BUT MORE IMPORTANTLY – MISSING ITEMS!!!! Typically when doing this job, it is very common for the washer and rubber gasket to “stick” up inside the tube or channels where the pilot screw goes up into the carburetor. You have to know this and know what to look for before you pull out the pilot screw! What you will be dealing with is seen below. TINY PARTS! Don’t lose them!
NOW FOR THE SWAP TO THE ADJUSTABLE PILOT SCREW
Now you will swap the spring, washer, and rubber gasket on the new adjustable pilot screw and insert it into the carburetor’s pilot orifice. In my particular case, the rubber gasket and washer were still inside, so I used a tiny poker to stand them up inside the tube so I could align and install the adjustable pilot screw.
Turn the adjustable pilot screw all the way in so you know where to start your counter-turns out from.
My setting was 2.75 turns out from the bottom. My bike has an aftermarket FMF pipe with other carb adjustments. Again, 2.5 to 3 turns out will most likely be your pilot setting, but the more closely you pay attention to your factory setting and put this adjustable pilot screw back in the same, it should result in the same running condition.
With the new adjustable pilot screw in place and adjusted to my 2.75 turns out, I marked this setting on the exterior of the carb pilot tube. This way, when I am in the mountains and make any adjustments and return down the hill, I will know where to return the pilot screw to my base spec setting.
TUNING
Go up – air is this, screw adjusts the fuel. Less air – less fuel. Screw in to reduce fuel.
Think about when you were removing and installing the screw, SMALL INCREMENTS!
TDUBWilly on the TW200 forum:
https://www.tw200forum.com/threads/extended-pilot-screw-for-on-the-fly-toolless-adjustment.74834
Purchase 2001+ TW200 Pilot Screw: eBAY: https://www.ebay.com/itm/266975739308
Purchase 1987 – 2000 TW200 Pilot Screw: https://www.ebay.com/itm/266987802606