400 power!

[Mike Lenz]

I found an service info sheet in my old dealer stuff dated aug 15 1975. It reads:
We have been experimenting with the 400 Enduro and have come up with a better running, better milage, better torque and soomther running machine for the woods. What we are doing is remachining the head for better combustion.

If you have the facilities to have the head machined it should be cut to 45cc.

DO YOU THINK THEY WERE JUST CUTTING THE HEAD OR WHAT?? I ALSO HAVE SOME 400 PORTING AND PIPE SPECS IF ANYONE IS INTERESTED.

 

[Larry Perkins]

Mike

I remember these mods from The Day.  I think they milled it till the combustion volume was 45cc.  Besides the port and pipe mods there was also a carb slide mod to help the 400 off idle.  It changed the cut-away and I remember it helped the loading up at slow speeds.