Here we go ! Another rebuild thread
Road Warrior
Joined: Jul 2013
Posts: 1,476
Likes: 5
From: Florida
You must be at an ideal state of tune, because you have to have some really high cranking compression (for the street)! Guessing your north of 200?
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Cruiser
Joined: Sep 2013
Posts: 159
Likes: 0
From: CNY
The guy who blueprinted my eng has built 1000,s of street engs. 100,s of 1st place dyno shootout out bikes and has 3 patents on int. and head design . i think i'll take his word when he say's that 9.7:1 is the perfect comp. ratio for my cam set up .
Road Warrior
Joined: Apr 2007
Posts: 1,952
Likes: 15
From: Senoia, Ga., by way of Miami, Fl..
I think your right on.. I've been researching my *** off, bothering some very knowledgeable guys, trying to figure out what I want to run in mine.. I actually chose a little bigger cam to get the number I wanted, rather than cutting the new pistons. But, frankly, I'm a bit baffled that Wiseco doesn't offer anything between 8.5 and 10:1 for our Evo's.. My belief is that you need to keep your cranking compression near 180 to meet a safe balance between power and reliability w/o detonation.. Shaving those pistons or opening the combustion chamber are the only way to get it once your decided on a cam.. Looking forward to your results.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,079
Likes: 2,151
From: Ohio
With a 36 degree intake timing 9.7-9.8 is safe, 10-1 is optimal for power but starting to enter detonation prone, needs perfect AFR plus timing. A big bike in 95 degree weather loaded, 36 degree intake timing 10-1 will detonate in the roll on area, light bike won't as noticable.
Shaving pistons is common in the automotive world, thought they call it flycutting but never hear much if it with Harley's.
Shaving pistons is common in the automotive world, thought they call it flycutting but never hear much if it with Harley's.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
I think your right on.. I've been researching my *** off, bothering some very knowledgeable guys, trying to figure out what I want to run in mine.. I actually chose a little bigger cam to get the number I wanted, rather than cutting the new pistons. But, frankly, I'm a bit baffled that Wiseco doesn't offer anything between 8.5 and 10:1 for our Evo's.. My belief is that you need to keep your cranking compression near 180 to meet a safe balance between power and reliability w/o detonation.. Shaving those pistons or opening the combustion chamber are the only way to get it once your decided on a cam.. Looking forward to your results.
when they did the first design we still had leaded fuel at the pump, not every place but you could still get it, and 10 and even 11 to one was not out of the question, the 11s are gone but they are a small company and being that it cost them plenty to change out Now for a motor 30 years old when the cast pistons actually do for me a better job in an evo -- jz
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
With a 36 degree intake timing 9.7-9.8 is safe, 10-1 is optimal for power but starting to enter detonation prone, needs perfect AFR plus timing. A big bike in 95 degree weather loaded, 36 degree intake timing 10-1 will detonate in the roll on area, light bike won't as noticable.
Shaving pistons is common in the automotive world, thought they call it flycutting but never hear much if it with Harley's.
Shaving pistons is common in the automotive world, thought they call it flycutting but never hear much if it with Harley's.
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Seasoned HDF Member
Joined: Aug 2008
Posts: 5,079
Likes: 2,151
From: Ohio
Ya Highbarst, when you find a great engine builder you have to trust him, experiance is a good to have on your side when 100 miles from nowhere or the Evo needs a little respect with the boys.
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Cruiser
Joined: Sep 2013
Posts: 159
Likes: 0
From: CNY
Some more progress today taking my sweet time with this motor triple checking every bolt torque before I go on to the next . Motor at a standstill untill i get my frame back . Installed my semi homemade front marker/signals they started off as rears with the wiring going through the bot took them apart drilled new hole and directly bolted them to the upper tree . Made a new wire harness for rear light and installed new rear marker/signals to match the fronts . [IMG
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