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I understand that using 95 cyls and full topend with special pistons with an evo bottom, you can get 100 in. Can bigger pistons be used with special cylinders? what is the largest piston that can be used on an evo?
 

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I have a buddy that has a Fastrac bike that came with a Fatso Motor that is like you asked, it is 100 cubes. Although I believe that you cannot just take a "regular" evo motor and do this. I think you need to use the Sputhe (?) cases. I am certain that someone who is a "wrench" will pipe in soon
 

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am finishing a fatvo now. sputhe cases relocate the cylinder studs. sputhe makes the pistons also. as well as the pushrods. as far as i know, you can go a little more on pistons but no more on stroke.

sputhe says to keep it at 100 inches.
 

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Flash Motor Works did the build. Ported the heads, R&R Cycle reworked the pushrod holes in the TC heads. Harley cast 95" kit pistons for 4" Stroke but motor has 4.250 " raises Mech. CR to 9.9:1. Dave Mackie DM530 cam corrected CR is 9.04
Harley non highlighted cylinders were slightly beveled for clearance between cylinders due to 5.875" deck height. Pistons were slightly clearance . S&S Beehive springs, Black Diamond valves.
I estimate 105 HP & 110 TQ.
 

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either the Axtell or Sputhe 97"/95" big bore kits are about as far as you can go on bore using the Evo stud pattern, somewhere about 3.780 bore & using Evo heads.
 

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Damn that Ultima stuff is looking NICE!
 

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Note that the Rear Head cooling fins needed to be clearanced near the post tube in front of the oil tank. Only noticeable if you look hard and know what your looking for. Other than that. You would never know.
Motor runs great. Oil temp never above 180
 
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