12 replies to this topic

[needy1]

a 780 bored out .20, how may cc would it be?

[315DooRider]

a 780 bored out .20, how may cc would it be?

819cc roughly, you should not reinvent the wheel, have not heard of this build much or how common that piston size is. I know the 830cc which is the 72mm skidoo piston is much more common and you can get sleeves plus more info on the build. Good luck

[96-780]

buy the pistons first and give them to whoever is gona do your cyl. work. I dont think 20 thou. brings a 780 anywhere close to 819 cc

[maluchm]

69.5 bore x 68 stroke x 3 cylinders = 774cc (Stock size for the type 779 motor)

Assuming you meant 20 over in inches that is 5mm and piston sizes go in mm so.....

74.5 bore x 68 stroke x 3 cylinders = 889cc (Standard BB size thru Wiseco)

After that you have to change to the rotary valve motor twin pistons for the 925, 950 and 975cc

The 819 is the third overbore at 1.5mm.

Wiseco piston sizes

Calculate engine displacement

[gibs]

I don't see how 20 thousandths of an inch is equal to 5mm.....

[IcutMetl]

I don't see how 20 thousandths of an inch is equal to 5mm.....

Exactly; its roughly 1/2 a millimeter

[maluchm]

a 780 bored out .20, how may cc would it be?

.20*25.4 = 5.08mm

OR

.020*25.4 = .508mm (Like 96-780 called it) - Would make a 784cc

Do the math fellas...Original OP specified .20 over. Everything on theses sleds is Metric.

[Mach-ZX]

.20 is 200 thousands. Some people are thinking .020 which would be a 20 thousands oversize.

[Rhubarb]

20 thou over is only .5 mm not 5 mm when doing calc. You are correct .2 is 5 mm but twenty thou is not

[96-780]

.20 is 200 thousands. Some people are thinking .020 which would be a 20 thousands oversize.

oops

[6KJR]

Haha. Lets head off to math class..

[needy1]

.020 thou is .508 mm and i just went on the wiseco site and it lists at 785 cc. my pistons are wisecos. thanks for the help guys.

[maluchm]

Ding....Fries are done!