Nikasil cylinder cleanup pics and questions.

[SoopermanLuva]

Good evening, gentlemen!
I'm currently trying to clean up a Nikasil plated cylinder from an 036. It had some aluminum transfer from the piston and some scoring. I tried please clean it up with sandpaper but the plating is very hard and it doesn't really do anything. So I went ahead and took some fine diamond lapping paste and put it on my little honing device that I built. Now I have a pretty uniform satin finish inside of the cylinder. I still have still have a couple of lines around the exhaust port and my question is what I should try to clean them up or just let them be. So spot actually see was very smooth to the touch but those cuffs are still visible. Splitting seems to be still intact because of Steel pick that I used doesn't really scratch the cylinder walls. But it does leave some fine scratches, which I think is the result of the relatively coarse finish. It's not soft by any means. I'll hit it with a fine paste later. This is just a rough draft. Tested with a shot piston with just one ring on it just by pushing it in and out and there is definitely compression. Any thoughts and suggestions appreciated.

 

[Griffdog1]

Looks pretty good. The best way to do them is to use the "Mastermind" method, making a mandrel out of a big nail and rolling your emery cloth on starting pretty course. As you have discovered the nikasil plating is very hard and you will not wear through it. You are probably too smooth at present as the past will essentially polish the plating - you are going to have to make sure that this is extremely clean with warm soapy water, after giving an initial wipe down with a clean rag and some mineral spirits or the like. I use a scotchbrite pad, (again as per mastermind worksaws) as the final finish. If you have not seen Randy's videos on cylinder cleaning look at them.



Really the proof is in the pudding. If you can get the saw to pull 150psi with reasonable squish it will run fine as a general working saw. Sometimes I find it is best to put them together and see how you are going. Just check your ring gap and squish if you are removing base gasket.

 

[SoopermanLuva]

Looks pretty good. The best way to do them is to use the "Mastermind" method, making a mandrel out of a big nail and rolling your emery cloth on starting pretty course. As you have discovered the nikasil plating is very hard and you will not wear through it. You are probably too smooth at present as the past will essentially polish the plating - you are going to have to make sure that this is extremely clean with warm soapy water, after giving an initial wipe down with a clean rag and some mineral spirits or the like. I use a scotchbrite pad, (again as per mastermind worksaws) as the final finish. If you have not seen Randy's videos on cylinder cleaning look at them.



Really the proof is in the pudding. If you can get the saw to pull 150psi with reasonable squish it will run fine as a general working saw. Sometimes I find it is best to put them together and see how you are going. Just check your ring gap and squish if you are removing base gasket.

Thank you for the reply! Yeah, I've seen that video. Did a bit of research before attempting this. I made a hone that has flaps of sandpaper on it, removed transfer and smoothed out the whole cylinder. From my understanding, the thickness of the coating is about .008 or 0.2 mm. It's easy to remember, because it also happens to be the ignition coil gap on the 036. And that's actually pretty thick. So, are you saying, my finish is actually too fine at this point? I think it looks finer on in those pictures, than it actually is. It's a 20 micron, about 800 grit paste that I used. Looks like the brushed stainless they put on appliances and such. It also sort of scrathes, which is puzzling to me, but I'm guessing it's because the scuffs have those little peaks that are fairly brittle. But the surface is nowhere near as soft as the aluminum of the cylinder.
And yeah, I'll be taking a lot of time cleaning up that one. I want all the diamond out of there before I start it. This paste will eat the rings alive.

 

[Poleman]

I' with Griffdog....Looks pretty good! If there's any deep groves in the wall you won' get them out without going through the plating so be careful there because that will render the cylinder worthless.
Use you thumb/finger nail to feel the areas and for any roughness other than a grove. If you don't feel anything go one step further and use a new ring slowly pushing it down the cylinder with a piston to keep it square and check to see if you see any light wnder it and the wall from a bright flashlight. Check closely in the known bad spots.
When your satisfied that there' no more transfer hit the cylinder with 400 grit sandpaper then wash in HOT water and dish soap. Air or blow dry and reinspect. You should be good to go.

 

[SoopermanLuva]

I' with Griffdog....Looks pretty good! If there's any deep groves in the wall you won' get them out without going through the plating so be careful there because that will render the cylinder worthless.
Use you thumb/finger nail to feel the areas and for any roughness other than a grove. If you don't feel anything go one step further and use a new ring slowly pushing it down the cylinder with a piston to keep it square and check to see if you see any light wnder it and the wall from a bright flashlight. Check closely in the known bad spots.
When your satisfied that there' no more transfer hit the cylinder with 400 grit sandpaper then wash in HOT water and dish soap. Air or blow dry and reinspect. You should be good to go.

Thanks for the reply! The cylinder is smooth to the touch. I also keep a pick with a sharp tip to locate scratches. There's one scratch left which isn't deep anymore and I probably won't bother. The ring trick is a nice one. Right now I can get compression by just moving a piston back and forth with my fingers and holding my thumb over the spark plug hole. Is it necessary to put a crosshatch pattern on there? So there's no reason go up in grits any further? How fine is too fine in this situation? Because to me it still feels a little rough, to be honest and I've never seen a new OEM cylinder, so I don't know what the benchmark is here.

 

[VA 372xp]

I just did a 288 cylinder that was first time i cleaned aluminium of the plating in a cylinder i used a strip of fairly agresive sand paper taped to a pencil in a drill and hand sanded to took about 45 minutes.

 

[VA 372xp]

I didnt take a picture after green scotch brite but she was smooth !

 

[blsnelling]

As you have discovered the nikasil plating is very hard and you will not wear through it.

It's not hard at all to go through the plating using power tools. That's why I prefer to remove all transfer by hand.

 

[SoopermanLuva]

It's not hard at all to go through the plating using power tools. That's why I prefer to remove all transfer by hand.

Hey, Brad! Since it's my first time doing this I would like to ask stupid questions just to make sure. How do you know when you're actually through the plating? Color change, very soft aluminum that scratches easily? Should I crosshatch it and how fine of a finish do you put on the cylinder walls? I went ahead and honed the whole cylinder since there were a few minor scratches on the intake side as well. The saw was run with a very old air filter before I got it.

 

[drf255]

When it’s all shiny, it’s tough to tell plating from aluminum. The color is lighter on the aluminum than the Nikasil.

If you go through the plating, it’s typically by the port edges and with power tools. The sand paper will dig in on the side of the port opening its rotating towards.

I personally use acid, followed by hand sanding/3 stone hone/scothbrite hone.

Acid, applied slowly and methodically with a Qtip, is easy to control. Just gotta be careful by port edges and by the squishband. Also, if any area won’t stop fizzing, you could have a pit. Stop ASAP and neutralize the acid. You don’t want to undermine the plating. Add acid, wipe, sand, repeat. I neutralize with any basic solution. Baking soda works well, but I tend to toss the jug in my USC, which already has a basic high pH solution in it.

Using acid also stops the “polished transfer” issue. It’s not that hard to polish the transfer so you can’t see it against the background of the Nikasil.

Contrary to popular belief, new OEM jugs do indeed have a crosshatch to them.

Your finish sand must be very smooth. IMHO, and respectfully, the finish that VA372 is showing above is too coarse for my taste. That will chew up a piston skirt in no time, especially if on the intake wall.

 

[SoopermanLuva]

When it’s all shiny, it’s tough to tell plating from aluminum. The color is lighter on the aluminum than the Nikasil.

If you go through the plating, it’s typically by the port edges and with power tools. The sand paper will dig in on the side of the port opening its rotating towards.

I personally use acid, followed by hand sanding/3 stone hone/scothbrite hone.

Acid, applied slowly and methodically with a Qtip, is easy to control. Just gotta be careful by port edges and by the squishband. Also, if any area won’t stop fizzing, you could have a pit. Stop ASAP and neutralize the acid. You don’t want to undermine the plating. Add acid, wipe, sand, repeat. I neutralize with any basic solution. Baking soda works well, but I tend to toss the jug in my USC, which already has a basic high pH solution in it.

Using acid also stops the “polished transfer” issue. It’s not that hard to polish the transfer so you can’t see it against the background of the Nikasil.

Contrary to popular belief, new OEM jugs do indeed have a crosshatch to them.

Your finish sand must be very smooth. IMHO, and respectfully, the finish that VA372 is showing above is too coarse for my taste. That will chew up a piston skirt in no time, especially if on the intake wall.

Very helpful post, much appreciated! I noticed That the hone takes off more at the ports and used a fine lapping paster with very frequent checks to not take off too much at once. Unfurtunately, acid is not that easy to get around here, so I did the honing method. I hit it with a finer paste to slightly polish it up, not mirror shiny, of course, but to take off the scuffs so they don't grind away the new rings. I actually noticed the crosshatch pattern on the jug before I sarted working on it. It was still there below the intake port, even after 20+ years. Very impressed with the quality of OEM cylinders.

 

[CristiRo]

I just cleand my cylinder by hand with a scotch brite type sand paper. It worked very well. No "machines" involved here

 

[blsnelling]

You'll know if you went through the NiSi. It will be much lighter in color. I use 320-grit ball hones for a final finish.

http://www.baileysonline.com/Chains...Hones/Set-of-5-Silicon-Carbide-Flex-Hones.axd

 

[SoopermanLuva]

I just cleand my cylinder by hand with a scotch brite type sand paper. It worked very well. No "machines" involved here

Looks very nice. How much time did it take to get it there?

 

[SoopermanLuva]

You'll know if you went through the NiSi. It will be much lighter in color. I use 320-grit ball hones for a final finish.

http://www.baileysonline.com/Chains...Hones/Set-of-5-Silicon-Carbide-Flex-Hones.axd

Okay, thanks! Gives me confidence. I'll try without the crosshatch first, seems smooth enough for now. Unfortunitely it will take half an eternity for those hones to get here, but they sure are nice. Did you have problems with the hone catching on the ports?

 

[CristiRo]

Looks very nice. How much time did it take to get it there?

Aprox. 30 min. to say so. I went a little at a time. It as the first cylinder clean up for me so no hurry.
I also was pleased at the end on how it came out.

 

[pioneerguy600]

The ball hones are hard on the port edges but very low RPM for a very short ET will clean all that is needed. They suggest 600 _ 800 RPM and only like 15 seconds of turning. I watched a chainsaw mechanic at a repair shop run the hone for approx 2 mins at 8000 , spraying WD40 continously and without even looking he announced, there, done and ready to install. That was a painful moment for me.

 

[SoopermanLuva]

It lives! I'm still experimenting. Put a scored piston in there to see how far I can go and still have the saw run. Of course the piston has been smoothed out, the grooves redone and I had to make a new piston ring, but the saw runs and idles. Pictures and videos if anyone is interested. And thanks everyone for the input on this.

 

[CristiRo]

Glad to hear that you put it back together and works!
You can post for sure here a clip(can be uploaded with youtube and post the link here).

 

[SoopermanLuva]

Here are some pics of the piston and the little contraption I came up with to grind down piston rings to proper thickness. Apparently, there are multiple versions of the pistons for the 036 and newer ones have thicker rings. I have an old one, so it doesn't fit. And, of course, the ones I need are not available anymore around here. So I took off some metal on both sides to make it line up with the pin properly. For some reason I have no picture of the exhaust side of the piston, but it initially looked something like this:

The rings were stuck pretty solid, had to break one to get it out. So the grooves were peened, over and I used a guitar pick with sandpaper on the side to clean the waste out of the groove. After installing the rings (old ring on the bottom, not a lot of wear on it) it looked like this:

And here is my ring grinder. Just a cheap broken chinese piston with piston rings used as spacers. Keeps it flat enough:

Blased the crankcase with carb cleaner and the saw upside down a few times to get out remaining aluminum chips, dried and reassembled. There was also some aluminum in the muffler. The cylinder was scrubbed with a brush in warm soapy water, rinsed, blasted with carb cleaner and gas before I put in the piston. New OEM circlips as well.