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Old 01-29-2013, 10:08 PM   #82
Road Hog
Joined: Apr 2006
Location: Aussie Land
Oddometer: 3,791
Originally Posted by JMo (& piglet) View Post

As John explains above, the combination of a longer rod and adjusting the position of the crank pin will give the necessary stroke to retain the standard bore/cylinder etc. As he explains,the trick[y bit] will be to create a piston profile that creates enough compression while at the same time misses the valves when they are extended - the 690 Rally cam (which should help boost power) has a longer overlap than the stock cam, so things could be a bit tight in there - hence the prototype build and bench test before we go to production with the final specification...

Seeing your using the same compression height as the stock piston,
and using a longer connecting rod, with the shorter stroke.
this will change your rod ratio dramatically.

With this combination it will like a smaller port volume.

Thats why i did this

Good piston guys like,
Venolia, BME, etc etc
Those guys can copy your combustion chamber shape,
upload that profile into the C&C and then can machine the crown of the piston to suit.

It saves alot of time than the old days.

Good luck
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