The KB-DM is a Yamaha pipe with a narrower power band but unlike many narrow power band pipes that have a big spike of power in the middle, the KB-DM makes good power at the low end. It is a good pipe for tracks that have tight corners where you need to pull strong off of the corners.
Header- To get the most out of this pipe we strongly recommend the use of the matched KB-DM header (part number 101-125). Most other headers will not let the KB-DM pipe give you the amount of low end or power band width that this header does.
Flex- 9 to 9 3/4", starting at 9 5/8"
Clutch- At 9 5/8" start with the clutch at 10,600 to 10,800 RPM. Raise the clutch approximately 200 RPM for each 1/4" shorter that you run the head pipe. Lower the clutch approximately 200 RPM for each 1/4" longer that you run the head pipe.
RPM- Top RPM will vary depending on the track and head pipe length. At 9 5/8" on most speedway tracks, gear for 14,300 to 15,000.
Temperature- This pipe draws a lot of heat in the motor. The shorter the head pipe is run, the hotter the motor will run. Let your temperature be your guide as to how short is to short on the head pipe length.
Carburetor- The temp can be some what controlled by running richer than normal carb settings. Start out your carb tuning with a richer setting than usual and adjust from there.