58 and 60 mm crankshaft

[mickdale]

i know it may be a bit more involved than plain simple but can someone please tell me the difference in engine charecteristics a 58 and 60mm stroke crank will have on an engine..........

i am thinking of putting a 60mm crank in a near standard engine (either SIL cast iron 200 or rapido classic or ali finned linered barrel)

ps will i need to use a packing plate or can i get away with thick gaskets? - (new sil 200 casings)

cheers
mick

[grimspeed]

more torque !

[mickdale]

as in the ability to pull the bike more under stress without losing revs

assume port timings arent badly affected?

packing plate slightly moving ports up barrel so more revvy????

cheers
mick

[shocky]

as in the ability to pull the bike more under stress without losing revs

assume port timings arent badly affected?

packing plate slightly moving ports up barrel so more revvy????

cheers
mick

IF PACKED CORRECTLY THE PORTS DONT MOVE as the rod lenght pushes the piston up the cylinder, so a packer in effect moves the deck height upto compensate you can pack the top if needed instead this will lower the tranfere timing giving more torque you will have more inlet as well but less rev on ability ,its a good way to get a good touring tune ......

[mickdale]

thanks shocky - ive got one of those lth reed blocks (im hoping will fit under the LI panels with a mikuni tm24 and bellows????) so maybe more inlet timing wont hurt

maybe need a tuning shop to blend it all in as they'll know whats what

didnt want to get a 60mm crank and it not be right for the application

cheers
mick

[shocky]

thanks shocky - ive got one of those lth reed blocks (im hoping will fit under the LI panels with a mikuni tm24 and bellows????) so maybe more inlet timing wont hurt

maybe need a tuning shop to blend it all in as they'll know whats what

didnt want to get a 60mm crank and it not be right for the application

cheers
mick

its one of those things you gotta put together and measure
some say the indian casing have a deck height that is differant from and italian/spanish one i think its 1 mm higher so this will work in your faivour if you dont want to use a packer the head could be recessed so the top of the piston doesnt hit the head or to give you some squish,
i normally use a thin base (measure it) gasket and then a few head gaskets of diff thickness say a .5mm and a 1mm together when it bolted down i measure the squish at 4 points i can then work out how thick the packer needs to be. if you have say a 1.3mm squish then the packer needs to be 1.5mm(both head gaskets sizes combined ) or if your base gasket is .5mm a 2mm one will be near i try were poss to not use a head gasket just sealant ,there are many variatons off thicknesses gaskets come in the above is so you can see how to work it out
the squish size1.3mm is in the middle of whats acceptable in most peoples view and gives a good safety margine
The reason i use a couple of old head gaskets is so i dont have to buy several packers some of which i wont ever use

[mickdale]

thanks shocky
will put it all together and try it out

will check timings with degree disk at the same time and see if anything needs to be done

on a + note on my last sil 200 with normal stroke the crown of the piston didnt clear the exhaust port at bdc so a 60mm stroke should

cheers
mick