MrBenn
Firstly, I apologise. I know this does not relate to 851s or 888s directly so please feel free to delete this question.
I have an s4 crankcase, gearbox and other bits that is currently homeless. It was destined for an 888 frame but real life took over and I got rid of most of what I had.
As I am not the wealthiest on the planet I am starting up again. Can a 996 Crank fit in these cases? Can I build this as a 748 for revving goodness and less expense than s4 crank and rods.
Cheers,
Alan
nine16
I'm pretty sure you can fit the 996 crank. But that doesn't mean you are building a cheap motor--you would have to get custom rods or pistons or you'll be smacking into the heads or have no compression.
stafford
There is a 1mm packer for the base of the cylinder to overcome the stroke issue..
marvin
Stock rods will be fine. It's the piston pin height that is the difference.
p.s. A 916 S4 and a 996 both have the same stroke
brad black
the cranks are different single phase alt to 3 phase alt, so you need to go with options as per your alternator type. they also changed shim types with the swap, and i don't know if a single phase crank is wider across the main bearing inner seats than a 3 phase.
the 996 crank will have a different part number and different balance factor to the s4/st4, but should otherwise be the same. except for the 996 rods are small end located, and i'm not sure if they narrowed the big end pin at all when they went to that. if you use small end located rods (996 and testa) you need to use corresponding pistons. otherwise the rods wander around.
i personally believe the alleged 748 reviness is due mostly to the close ratio gearbox, and not any bore or stroke thing. put light crank/pistons/rods in it and it'll rev like a demon. but put a close ratio box in it and it'll feel racy.
a 900 crank is great with 916 pistons as you can space the cylinders up a bit and have no belt tension issues and good comp and squish.
as marvin says, the piston compression height takes up the variation in stroke as the rods are all the same length. so the 748 (or 853 kit) pistons are 2.25mm longer than the 916/996 pistons.
MrBenn
Thank you
Well.. This sounds like a job for some full on classified scouring and trawling through everyone's favourite auction site.
I have an S4 gearbox and I believe this is the same as the 748 so should be a nice and pleasant thing to do.
The 900 crank with 916 piston option may be a great one - Is this with 900 or 916 rods? Which 900 crank? Would an air-cooled monster give up its crank for such a job or would it be best to look for 900ss crank?
Sorry to ask so many questions that to the experts on here may appear really basic. This is my first trip into the world of Ducati mechanicals and I think ive been scared off by some of the details that I have read. Every time I think "ooh.. that should work" I see "do that and the engine will die in 2km's" written somewhere else on the internet.
