Harley Davidson Evolution Engine

Question

I have a 88 Softail, It has a S & S stroker kit and is 96 cubic inch. How much bigger can i go on the bore using the stock lower cases. It is a 3 5/8 bore with a 4 5/8 stoke.

Answer 1

You can go to 106 ci

http://www.nrhsperformance.com/ekitevbt....

Answer 2

Here's a different outlook on this.  If you want a performance engine get a performance bike.  You will have to change brands since harley are hardlys when it comes to performance.  You could probably pick up a used sportbike that will walk all over your hardly that is the same year as your softail for under 2 grand.

Answer 3

First make sure if you are an EVO 80 or Twin cam 88. Then call HD and ask what Screaming Eagle bolt on kits are available. You needn't buy one but those kits will tell you how far you can go with stock cases... This is a guess, but 103 with the 80 and 110 with the 88... BUT call HD to be sure.

*** I just re read... a 4 5/8 stroke??? are you sure you're only at 96 ??? 4 5/8 stroke is HUGE.

Answer 4

if you have the stock engine cases, I would NOT bore them at all.

they are very weak along the oil galley to the tappet blocks.   If you need more engine, get the S&S cases, or just get an entire engine kit and put your existing engine under the shelf to stick back in when it comes time to sell it, then use your new engine to build a custom frame up or something.

Patrick

Answer 5

If it's at 96" now, I would say your at about the limit. It was only 80" stock. I don't know how much the stroke added, but 96' is quite a bit.