Air Filters

[robnobrakes]

Does the 1977 400/4 respond well to the removal of the airbox and fitment of K&N or Uni filters with appropriate jetting?  The bike is fitted with a Yoshi (?) exhaust.

[Bryanj]

Yes as long as you spent time and effort to get the jetting right

[tom400f]

Yes it looks like a Yoshi exhaust. Its resonant at 6500 rpm or so. Coincides with max torque I believe but could be wrong about that.

I had such a pipe back in the day. Ran it with the airbox but (as far as I can recall) fitted "next size up" mains (sorry for the lack of clarity but I doubt I knew what I was doing anyway). Ran brilliantly like that.