Drilling Pistons??


There use to be a theory about "golf ball pitting" your pistons. Maybe he was talking about that?
 
forget about drilling stein..hop on your Viper and head out over here.Red should be good to go on now..I am warming up my sled waiting.It is pretty warm out now,wind chill is down.Lets put some miles on tonight.I used to ride in -30 to -35 below when younger and into 3 am in the morning bar hopping from St.Adolphe to St Agathe and back to St. Adolphe.Then after 2 am closing..we would race on the River..good old times.We never drilled pistons then either..lol
 
if you know how you can drill your pistons to lower the weight a bunch!!!! but you need to know enough about strength and durability you dont hurt the piston!!!

I would love to know the do's and don'ts aswell!!!!!!!!!!!!

someone here has to know about the swiss cheese piston!!!!
 
If there is a bridge in the exhaust you drill a small hole in the piston to lubricate that area. No bridge in these motors. Drilling pistons to make them lighter??? LOL!. If you want lighter pistons, go with Wiseco Pro-lites
 
I know lots of ice oval racers who don't drill pistons, but they definitely grind off the casting imperfections, and radius some of the stuff on the inner part of the pistons to shave some weight and balance the weights of the pistons. They say every little piece of weight saved helps them
 
I think hes talking about "gas porting" the pistons. Basically, a number of holes are drilled from the top of the piston, down thru into the ring lands. Theory being, combustion pressure is forced down thru these tiny holes and forces the rings out to make a tighter seal.

Tons more info if you google it.
 
Spinner18 said:
I know lots of ice oval racers who don't drill pistons, but they definitely grind off the casting imperfections, and radius some of the stuff on the inner part of the pistons to shave some weight and balance the weights of the pistons. They say every little piece of weight saved helps them
Click to expand...
the main purpose of doing that type of work to the pistons is to prevent cracks. Casting marks, and sharp edges is the first place a crack will start. Pistons are balanced by removing material from under the crown.
 
KneeDown said:
I think hes talking about "gas porting" the pistons. Basically, a number of holes are drilled from the top of the piston, down thru into the ring lands. Theory being, combustion pressure is forced down thru these tiny holes and forces the rings out to make a tighter seal.

Tons more info if you google it.
Click to expand...


All of my Yz250f mx bikes have had this done, when running wiseco hi comp pistons. I am not sure if the stock pistons were this way, but i do remember the high comp pistons being drilled.
 
ive heard of this type of thing, an old vmax 4 800 my dad had one had what they called a power up kit in it which was the head gasket, base gasket and drilling the piston, dont know where but it was supposedly to releive pressure on the downstroke and make it alot more responsive(something the vmax 4 wasnt known for). it was one of maximum performances sleds until we got it in about 99 or 2000, it was something they did before we got it from them.
 
I have a printout somewhere of a post a member replied to of mine years ago about doing this very thing.The hole that you drill out is the one in the side of the piston below the ring landing only you are supposed to use a step reamer not a drill bit plus there is some other things to do as well,jetting etc.I believe Bender or Hauck offered this as a power up package when the SRX first came out to give more hp.If I remember right the explanation the member gave me on the advantage of this is it essentially allows the engine to draw more fuel which is where the hp increase comes from.

I'm sure cylinder porting would be a better option for you if it's an increase in hp is what your after.
 
yes, i'm sure that he was talking about drilling out the boost port in the rear side of the piston. problem is, that just drilling it out won't do much. you need to make it a vertical slot to do any good. i won't tell the dimensions tho, as i need to keep some secrets to myself. the purpose of that boost port, is to help cool/lubricate the wristpin and bearing, and to allow any trapped charge from underneath the piston crown, to be allowed to escape up and thru the rear boost port in the cylinder. also, yes the vmax4's were given this mod in the day, along w/many other sleds.
 
stein700sx said:
Talked to a guy today that drilled his pistons for better performance. What and how does this work?
Click to expand...

You cant just drill them, the hole must be located so that it shuts off the port correctly but advances the port the other direction, its offset, not just a hole drilled thru the existing(srx/viper). A redhead benefits from having a port added in the correct spot.
I wouldnt do this alone, it does have a benefit when combined with work on the rear transfer boost port, but just doing the piston alone wont show you much of anything.
lubing the pin bearing, cooling the crown is 2 benefits but the other description told here is not what it does, but it doesnt matter... its not worth it by itself, its only part of the mod, you need both parts to gain hp from it.
 
You must log in or register to reply here.


Back
Top