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- Jan 31, 2010
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- 3,092
There have been dyno tests that showed the K&N reduced airflow over the standard Commando airbox. So you'd have to do some plug tests to really determine what the jetting should be if you switch to KN.
cyclegeezer said:I'm about at the end of the easy fixes for this problem I'm having with a 74 850 Roadster. Flat spot off idle, new needle and needle jets, new #3 slides, 220 mains, K&N filter, peashooter exhaust (probably EMGO)
MichaelB said:Verify BOTH needles are the correct 4 ring needle for cutaway spray tube.
2 rings for straight spray tube.
BrianK said:Do one change at a time to isolate cause and effect.
I'm betting you see great improvement when you raise those needles...
Flo said:The needle should be "down" as far as possible, with the clip in the top notch.
BrianK said:The classic test for main jets is to run WFO for a few seconds, then close the throttle slightly to about the 7/8 open position. If it runs better and faster at 7/8 open throttle than when throttle is fully open, your mains are too small.
Select a road for this test very carefully!
Good luck.