big dog evo 117 motor in a fat boy
 

My friend crashed him big dog and totaled it. He bought it back from the insurance company cheap and is looking to part out some of the bike. My dad has a 99 fat boy with an evo motor. Could I buy an S&S crankcase and use the other parts from the big dog S&S 117 motor and put them into the new crankcase and install it into the fat boy? And would I be able to use the big dog clutch basket in the 99 fat boy as well?

Are the current crankcases damaged? If not I'm certain the crankcases for all Evos are the same, so that engine should swap straight over. With a 117" you will certainly need a beefed up clutch. When I installed my S&S 107" I found the primary chain was worn, also the teeth on the compensator, so renewed both of them at the same time.

The S&S SA (Special Application) cases are 1/4" wider than stock cases on pinion side, but doesn't cause fitment issues on the frames. Your 117" and my 113" share this trait.

Griz

I briefly toyed with buying a 145" I discovered that was in dire need a new owner! According to S&S it would fit my primary and trans (subject to frame mods), but is plainly much bigger all round than a wee 80" or 107"!

I looked into it and found it would be to expensive and may just be more cost efficient to buy a bigger evo motor since I sell stuff on the side. New stronger clutch basket, crankcase, get a shorter rod for the tranny since this was coming of a bike with a 300mm rear tire. Get a better starter, maybe rebuild the tranny to make it a 6 speed. I dont think the clutch basket from the big dog would work with the softail. So this project is shelved and installing larger pistons , cylinders, cam and heads is the way to go.

The motor will slide in as well as the clutch. And 6 speed gear set or whole tranny No problems.

Those emission 117"s are about .045" below deck, emission cam as well.
98-100 hp and at/near 118 ft/lbs.
They can easily be at 130/135 if wanted.:icon_smile:
Scott