High Compression Piston

[Matt400ex_17]

Recently my brother went into a shop and asked what he had to do to put a high compression piston in a 400ex. They had told them that he has to bore the engine in order to do so. I dont believe that this is so. He dont believe me so maybee if he seen some responses on it he might... I think that you just replaced it instead of the old. Please let me know if im right or if im wrong!!

[VegasEx'r]

Usually when you say you are putting in a high-comp piston, people automatically assume you are putting in a larger piston as well. If he wanted to increase his displacement & up the CR at the same time, he would need to bore the cylinder. However, you can buy a stock bore high-comp piston. So you are correct, he doesn't need to bore the cylinder (remember though that if he replaces the piston, he MUST hone the cylinder). The shop may have assumed too much, & you know what happens when you assume something.

[RED121572]

....and how!

[330EXman]

YES VEGUS I RIGHT ON.

i did this mod to my 300ex and i bought the stock bore size only in high compression and i did the mod myself to save money.

yes make sure they take and hone the cylnder IF THEY DONT THE PISTON RINGS WONT SEAT RIGHT AND YOU WILL LOOSE COMPRESSION AND WEAR YOUR RINGS OUT!

this mod is easily done without boring.

HOWEVER IF THIS IS AN OLDER MOTOR THAT WAS PRELY TAKEN CARE OF AND THE CYLNDER WALL ARE SCORED AND WORN YOU WILL HAVE TO BORE MOST LIKELY,!

LATER GUYS