I'm looking at a 15th anniversary fatboy that the guy punched the 95inch cylinders to 103s...and he left the stock cams.. Odd... What's ur guys take on this... I would say he made them to thin no?

 

I believe the cyl bore is the same for 95 and 103 motors. The difference between a 88 cuin,and a 95cuin is the cylinder bore. To make a 95 cuin motor a 103cuin, you have to change the crankshaft. I would think leaving the stock cams would leave the bike kinda gutless. I'm thinking he went from a 88 to a 95, and they usually went with 203 or 204 cams. That was a popular upgrade. How does it run?

 

Well its a 15th anniversary fatboy so they come 95 inch stock but really there 88s

 

I agree with both counts. You can punch an 88 to 95 with just jugs and pistons, but 103 needs a rotating assembly. AND 15th A/E Fatboys are 95 inches stock.

 

When the 88cu in motors were the standard issue for Harley, the CVO bikes were 103s. It's all in the bore not the stroke. Then in 2007, when Harley went to the 96cu in motors, they accomplished this with a new crankshaft that increased the stroke length not the bore size. So a 96cu in motor has the same bore as an 88cu in with a different stroke and now the CVO bikes are 110cu in and the bore and stoke is different from the 88cu in. The stroke is the same on a 96 and 110 motor just the bore is bigger.
So yes you can make an 88" motor into a 103" just with a bigger bore.

 

Hold on Dyna Rider, no yah can't. In order to get that displacement out of an 88 or 95 inch motor, you would have to split the case, and bore the cases for bigger jugs. You CAN NOT simply bolt a 103 inch kit on an 88 or 95 inch motor and end up with 103 inches. That's like saying you can punch a 1200 Sportser to 88 inches just by punching out the jugs. Well yeah, you can, but you have to split the cases to do so. Maybe I misunderstood th OPs question, but I think that's what he was asking.

 

Then how did the motor company do it up until the 2007 model year ?

http://nwhog.wordpress.com/2008/02/0...ngine-history/

103 is the biggest bore an 88 stock motor can go to and still be reliable. To go bigger than 103, you have to split the cases and replace the crank...

 

Called the guy he's so full of hot air I passed on the bike thanks for info guys

 

Well, I am sitting here looking at my 2006 Harley Handbook and it says they did it by "stroking" the engine. Just like others have told you.

 

88 inchers have 3.75" bore, 95's 3.87" and you can get to 103 by using 4" pistons, all with the 4" stroke.

But the 103 S/E RoadKing ( 2002) was a 4 3/8" stroke with the 3.87" pistons.

The Anniversary Fatboy was still a 4" stroke with the same 3.87" pistons which held it to 95". The point is the owner of that bike could have gotten to 103 either way because Harley didn't offer a 103 in the Anniversary Fat Boy.

Only he could tell us how he chose to do it.

(BTW don't confuse the Anniversary FatBoy (95") with the Screamin' Eagle FatBoy (103").)