696 Engine modifications

[Raux]

OK, so been thinking...
696 specs: 88mm bore with at 57.2 mm stroke

the stroke on the 620 is 61.5
using the same bore you basically get a 750.
What kind of work would need to be done for the engine to be able to accept the longer stroke of the 620 crank?

Or would it be easier to get a larger bore? how big of a bore would the engine hold on the 696?
how about the 92mm of the 900 motors?
with old 92mm bore with the stock crank you basically get a 750 motor, or with the 620 crank you get an 800.

then valves...

what are you thoughts first on the bore x stroke capabilities of the 696 motor. i'm about to have the engine out of the frame... so been looking hard at what i want to really do with this bike.

[Duck-Stew]

Depending on the piston pin height of the stock 696 pistons, a 91mm overbore kit from CA-Cycleworks (There are two available BTW one for the 800 (859) and one for the 750 (799).) would turn your 696 motor into a 750.  (Valve to piston clearance and valve to combustion chamber clearance notwithstanding).

If you're going to stroke the motor, why not an 800 crank?  66mm stroke would be much more torque than the 620 crank would at 61.5mm versus your stock crank at 57.8mm.

(I have a low-mile '04 SS800 crank available for sale BTW... )

[Raux]

ok, so what would need to be done for the 66? any internal case mods?

would it be easy to run the stock bore . it gives me an 800 that way or an 850 with the 91 bore kit.

the 91mm bore kit with stock stroke only gives 750

what would be more cost effective?

ok i'll bite how much for the crank  

seems that stroking the motor with a valve job/head flow work would be a pretty good upgrade though.

Also thought about working the airbox or eliminating it.

[Duck-Stew]

If you left your stock bore, then stock or hi-comp 800 pistons should work in your 696 motor.  It depends on the piston design and if Ducati has changed the deck height of the 696 versus the older small case engines.  (Deck height is measured from the centerline of the crankshaft (big ends) to the top of the cylinder barrel BTW.)

The rods should be the same but I don't know as I haven't torn down a 696 motor yet.  No internal case mods to fit the 66mm stroke crankshaft.

$120 for the crank + shipping.

[Raux]

has anyone taken apart a 696 motor yet?

[sroberts152]

I think you may have the perfect bike to try it out on.   

[Raux]

GREAT  

oh.. and if anyone wants to donate parts to the cause for my efforts  

[Raux]

Ok here's some info i found. Seems the intake valves are the bigger 44mm. probably just need to clean up the intake runners and the airbox inside.

In the event of damage or excessive wear the barrel must be renewed as it has a silicon carbide coating (which provides the cylinder walls with excellent anti-friction and anti-wear properties) and therefore cannot be rebored.

Intake valve diameter 44 mm  
Exhaust valve diameter 38.5 mm  
The intake valve guides are made from cast iron, whereas the exhaust valve guides are bronze
Connecting rod Connecting-rod big-end diameter 43.67 mm
 Nominal diameters Ø 18 mm  
 Piston Ø 18 mm/0.020 to 0.015  
 Gudgeon pin Ø 18 mm/0 to 0.004  

[sroberts152]

GREAT  

someone needs to send me the shop manual   edit- may have it.. checking now

oh.. and if anyone wants to donate parts to the cause for my efforts 

Its too big to send...

http://ducatimonsterforum.org/index.php?topic=22342.0

[Raux]

Its too big to send...

http://ducatimonsterforum.org/index.php?topic=22342.0

yeah i got it.. forgot

[caperix]

The 696 uses a setup like a DS1X00 with a gasket between the cylinders and heads.  Because of this the overbore kits maynot work.  The heads flow beter with better cams and bigger valves than the 800 heads.  If your willing to split the cases I think an 800 crank could produce some more power.  I would love to see the results.  If you do tear into your motor if you can figure out if the bore spacing on the 696 is different from the older small case engines it may help me in a project.

[Raux]

The 696 uses a setup like a DS1X00 with a gasket between the cylinders and heads.  Because of this the overbore kits maynot work.  The heads flow beter with better cams and bigger valves than the 800 heads.  If your willing to split the cases I think an 800 crank could produce some more power.  I would love to see the results.  If you do tear into your motor if you can figure out if the bore spacing on the 696 is different from the older small case engines it may help me in a project.

i called the Kamna shop today but they said i need to talk to Herr Kamna who wasn't available today. soooo i'll call again. i had also sent them an email.
I expect they will say 'sure... how much money do you have' but i'll counter with... i know of an untapped market and now you have an engine to play with.

[Raux]

if i got the 66mm crank don't i need the rods to go with which would be shorter right? the 696 has a 10.7:1 compression ratio already so seems there wouldn't be much room for stock conrods to be used.

[Duck-Stew]

Either shorter rods, or pistons with a shorter pin height.  The piston pin height is measured from the centerline of the piston pin to the top of the piston face (generally not including the dome of the piston).

Likely, the pistons from an 800 would at least get you close providing the combustion chamber hasn't changed significantly from the old small cased motors to the new ones.

[Raux]

Either shorter rods, or pistons with a shorter pin height.  The piston pin height is measured from the centerline of the piston pin to the top of the piston face (generally not including the dome of the piston).

Likely, the pistons from an 800 would at least get you close providing the combustion chamber hasn't changed significantly from the old small cased motors to the new ones.

i was thinking the new combustion chamber design (which i read was one of the big changes between the 695 and 696) would work better with the stock 696 pistons. therefore, i guess shorter rods. but by how much? i'm thinking it's gonna need to be taken apart and measured and then decided...all of which is beyond me, so i'm back to waiting on contact from Kamna.