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Post by 190mech on Jul 18, 2014 11:59:52 GMT -5
If you have aluminum streaks in the cylinder,spray some EasyOff oven cleaner on them and let it sit for a few hours,rinse well with hot water,then sand the cylinder bore by hand with 220 grit wet or dry sand paper,sanding scratches should in a cris cross pattern(about 45 degrees),wash well again,now its ready for a new piston and ring set..
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Post by 190mech on Jul 18, 2014 18:28:06 GMT -5
If its aluminum deposits,it'll be a silver looking streak on the grey iron cylinder surface.Vertical scratches are even OK if they're not deep.. Here are a few pics of the "hand hone" method Ive used to refurb 2T stuff since the 70's; Here is a drawing of the pattern we want inside a piece of PVC pipe;  This is how it should look after the hand hone work(sorry this is a junk cylinder);  |
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Post by 190mech on Jul 19, 2014 4:17:19 GMT -5
May require a few applications of Easyoff,the cheaper Dollar General off brand oven cleaner has been doing a better job for me lately...
Go to Dollar General and buy their store brand cheap oven cleaner,spray some in a cup and brush it thickly on the aluminum scuff area,dont get carried away with is as it does eat aluminum..Let it sit a few hours and scuff the deposit off with a ScotchBrite pad,reapply oven cleaner as needed,you'll know if its thru the Nikasil on the first application.
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Post by 90GTVert on Jul 2, 2015 11:19:08 GMT -5
When honing a cylinder you're not really removing enough material from the walls of the cylinder to affect the size relationship to the piston/rings- that'd be more like "boring out". The video is kinda long- longer than it needs to be!- but I did my best to give full details and explain thoroughly. Hope this helps! www.youtube.com/watch?v=zcel7X4y04kGreat vid Niz!!Will want to clean the cylinder very well after the hand hone to remove the metal dust and sandpaper particles..Hot soapy water does a good job followed with WD40 and a white paper towel to test for cleanness.. |
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Post by 90GTVert on Apr 10, 2016 9:13:35 GMT -5
Extra-Fine Gray scotch bright on a old 3 shoe hone will polish off aluminum, and leave the hard Nikasil. The 3-M Scotch-Brite / gray #7448, ultra fine pad's are equivalent of 600WD paper. But do not tend to tear like 600WD paper does. Use plenty of flushing fluid,kerosene,solvent, Mineral spirits, with a bit of ATF works great, to keep it well flushed. I use a battery powered drill. Cylinder submerged in solvent & a bit of ATF. Hone slowly, cylinder submerged the in a large plastic coffee container and hone them with a wrap of scotchbrite, over the shoes. it slowly removes the softer aluminum. If if it is rubbed through in anywhere, you have a problem. Around the exhaust port area is usually where it rubbed thin. When finished wash the cylinder in boiling soapy water, then flush with hot water to remove any grit from remaining trapped in the transfers. (this last step is where people often shortcut. and the job will suffer) I am with 190 on the finish.Hand hone with 300 grit has worked for me in the past.IMO a power tool with fixed stones has a much higher likelyhood of removing the coating IMO.From the pics if that were a standard cast bore that looked like that I'd recommend a bore.But nikisal is a coating and blemishes much easier than cast.A comment 190 made as an aside which is typical of a pro is to check bore for roundness.If you don't have an internal caliper this can be done with a ring in a pinch.Place ring in bore just below where you might have a land and measure end gap in several places down the bore using the piston to make sure it's straight.Don't be concerned with a slight taper.Hope that makes sense. Here's the whole thread where the above quotes came from, with more discussion on cylinder cleaning and prep : 49ccscoot.proboards.com/thread/14376/oven-cleaner |
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