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Shaved cylinder


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Let me put this as politely as possible. You have no idea what you have. You don't know if the cylinders are decked on the top or bottom, or even at all. You don't know for sure that you have a 4 mill crank. The piston numbers that you posted in the other thread don't mean anything at all. You don't know what your piston to wall clearance is. You don't know what the squish clearance is. You shouldn't be replacing just 1 piston. Someone (a builder) needs to measure everything and advise you on the best way to put the motor back together for the type of riding you plan on doing. It's impossible for anyone more than 2 feet away from your motor to give you advice without knowing how the motor was set up before. There's a lot more to motor building than just making sure the pistons are even with the top of the cylinder at TDC.(Or not, if you are building a 4 mill without a spacer plate)

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First off if your local shop doesnt know what or where to go with your top end, HE IS THE LAST GUY TO BE BUYING ANYTHING FROM!

Any engine qualified machinist should be able to tell you what you need. Obviously your guy can't tell you what you need so he would still like to make a buck off you by selling you some of his JUNK! GO ELSEWHERE!

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Agreed, if it is just stock stroke long rods, run either a blaster style piston or the Weisco 795 series piston. Then have your head or domes set up according to which piston choice you make. If it is the 4 millimeter stroker long rod crank, you will need to also choose your piston and have the domes cut for the storms and style piston you choose. The difference between a stock and 4 mil dome will be 2mm deeper step and the angle of the squish band will be determined by whether you choose the blaster piston or Weisco 795 piston.

 

To clear things up for you, when the long rod crank came out it was to take stress off the rods in crank rotation yet it also has more dwell time at TDC and BDC. People used blaster pistons because they have a wrist pin height that is 5mm higher in the piston so it could be used in the long rod applications. Then some years back Weisco began producing their own piston for the long rod motors known as the 795.

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