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Discussion Starter · #3 ·
Isn't the FMF the best pipe for a stock bore engine anyway? Outside of cone pipes or unless you have a 38mm carb and a VForce3 or something. Then I've noticed there's about 3 FMF designs if not more. There's the Don Emler Signature pipe, the short Fatty with the middle curve and the long Fatty, which is what I have. Then there's also the Fat Boy which only lasted a little while until Paul Turner or Harley (or both) sent them a letter.
I have a 38mm carb, cleaned up ports, 200 psi compression, running 110 octane, v force reeds and DRW ignition. Power with fmf fatty hits hard at upper rpm and very narrow power band almost nothing below 5,000 rpm. Switched to another unknown pipe I have and it tamed the hard it, gave more bottom but overall seemed to be slower but more manageable out of corners.
 

· Super Moderator
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184 Posts
Discussion Starter · #5 ·
I just replaced an fmf with a Kenny Robert’s exhaust on my 85 and it was a huge improvement everywhere in the power. Now it has a noticeable “hit” almost as soon as I get past 1/8 throttle. You can hear it and feel it hit and it just spins the tires or stands up and the power stays there until I shift and doesn’t fade out. My engine setup is basically identical to yours but I have CR ignition.
Yeah I seen your thread that also convinced me. Don’t get me wrong the fmf is fun in wet dirt in a straight line but I think once I get it out on the desert and it hits the power band it’s just going to spin the crap out of the tires and I’m talking only half throttle there’s no easing into it at all.
 
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