First Porting Attempt MS 260

[bower4311]

Okay, I've done a lot of reading and this is my thread for my first attempt to make sure everything goes smoothly.

Here is the picture of my piston marked with a pencil through the exhaust. Is this correct and where will I know how much to take off the cylinder? One side measured .179 and the other .159, I did this measurement without the piston rings in, if that makes a difference I'll do it again if I have to. Is this normal to have the difference like that on either side?




Here is the carbide cutter I purchased on e-bay for this project.



For future reference searching "carbide burr single 1/4 1/8" should yield that burr. 1/8 will be the shaft diameter and 1/4 is the burr diameter. You could get the opposite with that search but it should be obvious which one to any newbies.

http://www.ebay.com/itm/Carbide-Burr-SC-51-Cylindrical-Ball-Nose-Single-Cut-1-8-x-1-4-x-1-2-x-2-/380642635006?pt=LH_DefaultDomain_0&hash=item58a011acfe

http://www.ebay.com/itm/1-4-Tungsten-Carbide-Single-Cut-Grinding-Burr-1-8-Cylinder-Shape-Fits-Dremel-/140699275550?pt=LH_DefaultDomain_0&hash=item20c254911e

 

[watsonr]

Leave .100 and you should be ok.

 

[bayard]

bump

 

[bower4311]

Leave .100 and you should be ok.

So that's the distance from the intake and exhaust ends after porting to the end of the piston skirt? As if I redrew my lines on the piston. And is it normal to have differences in the lengths of the port to the skirt end? Should I install the piston rings then try drawing it again, or should it not make a difference?

 

[blsnelling]

You could go as close as .050" without any issues.

 

[bower4311]

Is it normal to have differences in the lengths of the port to the skirt end? Should I install the piston rings then try drawing it again, or should it not make a difference?

This is important for me to know.

 

[Mastermind]

This is important for me to know.

Go by the wear marks in the jug.....

 

[bower4311]

Go by the wear marks in the jug.....

Looks clear enough here.

 

[Mastermind]

Looks clear enough here.

Just leave a little for it to seal.

Also on that saw I'd widen the bottom of the port and leave the top shaped as it is. Also lower the floor about a mm.

 

[bower4311]

Just leave a little for it to seal.

I'm going to cut thin strips of tape about 0.08 as a good compromise for my first time and lay them on the edge of the skirt line for when I grind

Also on that saw I'd widen the bottom of the port and leave the top shaped as it is. Also lower the floor about a mm.

I need specifics when you say port, does that mean the exhaust and the intake? Lower them a mm as I widen? What about the coating on the exhaust port? I won't be removing any from the top so at some point the coating will blend with the bare metal?

 

[Mastermind]

I'm going to cut thin strips of tape about 0.08 as a good compromise for my first time and lay them on the edge of the skirt line for when I grind



I need specifics when you say port, does that mean the exhaust and the intake? Lower them a mm as I widen? What about the coating on the exhaust port? I won't be removing any from the top so at some point the coating will blend with the bare metal?

I wouldn't worry about tape.....just use a business card as a straight edge and make a pencil mark.......degrease the cylinder with carb cleaner or starting fluid and the pencil will make a nice mark.

I was referring to the intake port. Just widen it a bit and lower the floor a mm or so......

Don't touch the roof or the floor of the exhaust. Just blend it in as best you can.....it'll be fine.

Don't forget to bevel the port edges.........If you don't have a round diamond burr use 220 grit sandpaper and slick it up good.

 

[bower4311]

I wouldn't worry about tape.....just use a business card as a straight edge and make a pencil mark.......degrease the cylinder with carb cleaner or starting fluid and the pencil will make a nice mark.

I was referring to the intake port. Just widen it a bit and lower the floor a mm or so......

Don't touch the roof or the floor of the exhaust. Just blend it in as best you can.....it'll be fine.

Don't forget to bevel the port edges.........If you don't have a round diamond burr use 220 grit sandpaper and slick it up good.

Thanks for the advice, I'm probably going to get started tonight. I'm going to take it slow, get the hang of it, it doesn't look like I'll be taking too much off anyway. I'll be posting pictures a long the way.

Where should I start with how much to take off? So far I've gotten leave as much as .100 and .050 is enough on the smaller end.

 

[Mastermind]

Thanks for the advice, I'm probably going to get started tonight. I'm going to take it slow, get the hang of it, it doesn't look like I'll be taking too much off anyway. I'll be posting pictures a long the way.

Where should I start with how much to take off? So far I've gotten leave as much as .100 and .050 is enough on the smaller end.

Just draw a line near the wear mark in the jug.......cut to that line leaving .050 or so. Your overthinking it.

 

[bower4311]

Just draw a line near the wear mark in the jug.......cut to that line leaving .050 or so. Your overthinking it.

I know, I just get nervous with something that I can screw up that would cost me money to replace.

 

[Mastermind]

I know, I just get nervous with something that I can screw up that would cost me money to replace.

If you stress on it you will ruin it. opcorn:

I do over two hundred a year.....just grab it and grind.

 

[nmurph]

If you stress on it you will ruin it. opcorn:

I do over two hundred a year.....just grab it and grind.

Yep, what she said:msp_wink:.

 

[Mastermind]

Yep, what "The Mastermind" said:msp_wink:.

No problem........fixed that too.

 

[bower4311]

Is a tool with 22000 rpms good to use?

EDIT: Reason being I rattled the bit around trying to smooth out the intake and it bent...guess I have to order a new one. I didn't have it fastened down like I should have. My fault.

 

[bower4311]

I'm probably going to try and tackle with files for my first time. I gouged up the intake pretty good, it's going to take a little filing to get it back smooth, I think It may end up raising the intake a hair. Should I order a file set? Or use a chain file?

 

[Mastermind]

Gives a guy a new respect for what we porting guys do huh?

Variable speed is your friend.