KX Guru Racing

One of the things that you start to notice when building KX500's or any other 2t engine is that there are some area's you would like to see a bit more oiling.
Here is a well worn KX500 piston..
Notice the vertical lines in it...
Those are all places I would like to see some more oil..


Here is the area's on the cylinder that need a bit more oil..
But how can you accurately transfer that vertical location to the piston?

Remember, you don't have a old worn out piston to work with that has the vertical lines drawn out for you
But the last thing you want to do is drill a hole in the wrong location and short circuit your engine
First things first, you need to mark to top of the piston with the location points you want to run vertical down your piston.

Next, pull the piston out of the cylinder and take a look.


Now for the hard part... Transferring the lines from the top of the piston to the sides...
You will need a "V" Block like this.

Here is the "V" block that I use..
I wish it was a little bigger but it works..

Put the piston into the "V" block and rotate the piston so that the mark on the top of the piston aligns with the edge of the block.
Once you have it aligned you can run a sharpie down it like so... Except.... IT won't work like this...

Now what???
Easy... Get a piece of material such as this piece of aluminum and raise the marker up a bit...

Now, run that marker down the edge and PRESTO!.... Oops...

Don't get in a hurry... If you mess up wipe the mark off and start over...

Sweeeeettttt

At this point you can mark your hole positions..
When you use the punch you don't need to wack it... Just a little tap will do ya..

I like leaving the piston in the "V" block because it holds the piston so nice.
Just be sure to air hose or wipe the piston and "V" block in between holes so you don't scratch up your nice new piston..

I intentionally used a much larger drill bit then I needed because I wanted to accentuate any errors I might have made.
Once done I put the piston back into the cylinder and ran the piston up and down to see if I exposed any of the ports..

As you can see this was a perfect job.
Yes, sometimes I get lucky

Special tools? The "V" Block... sure... but they are not expensive...

http://www.ebay.com/sch/i.html?_from=R4 ... c&LH_BIN=1

Have fun

Drill hole size?
You can use many different sizes.
.080" is what I like but you can use a bit smaller or a bit bigger with no issues.
.120 is the large diameter of the counter sink that I use.
Again, it's not too critical but I would not go any bigger or you might short circuit your engine
Smaller is ok...
Counter sink included angle?
Whatever, it's not critical.
I use 60 degree, 90 degree, and whatever else I have laying around