Paint inside crankcase?

Will'smotobikes19

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Apr 9, 2018
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Well I ordered a big bore cylinder that is painted black and got a cheap black ebay kit but I found out they painted the inside of the engine!-who does that? I guess what I'm asking is what is the best way to remove the paint it seems to be on there pretty good because steel wool barely touches it. Why would they paint the inside of an engine? the stock head was also painted where the spark plug protrudes. But I'll be using the cnc saucer head. If that paint started flaking off it could get into the bearings and cause more wear that's why I'm removing it.
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Also the magneto has been hanging off the one half of the crankcase and I noticed the blue wire isn't even attached and the ground isn't connected the solder didn't hold it.
 


crassius

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I used to get painted motors and they did the masking so poorly that I had a patch of black on both sides of piston - one for the exhaust port and one for the intake port

got it off with wd40, but inside case probably won't matter

in 60s we used to red-lead the inside of cases to keep oil from sweating out thru the crappy aluminum used back then
 

Island Racer

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Jan 25, 2016
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Hi guys, i did not post for a long time, my engine clutch did not work, and the bicycle did not run for 1 year, standing outside, anyway see the pictures,

Regarding painting, would you leave the engine like the pictures and then sandpaper or steelwool it and paint ?

Or disassemble further and then paint ?

I will buy the high temp black paint and paint ALL ENGINE black (i guess)
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The clutch pack NUT was loose, so that is why it was not working, do you use locktite on that nut ?
IMG20180918180320-1560x2080.jpg

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IMG20180918180438-1560x2080.jpg
 

crassius

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I don't use loctite on anything in these motors - be sure woodruff key is in correctly, and seat hub on the tapered shaft with a few taps with mallet.

I wouldn't try to paint at this point, as a lot of fuel & grease has seeped right into that metal, cleaning probably won't get it all.
 

Island Racer

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I don't use loctite on anything in these motors - be sure woodruff key is in correctly, and seat hub on the tapered shaft with a few taps with mallet.

I wouldn't try to paint at this point, as a lot of fuel & grease has seeped right into that metal, cleaning probably won't get it all.
Ha ok, so you think that if i sand the case & spray it with brakecleaner that the aluminium body is still saturated with fuel end 2stroke oil ?

Good point ... Hmmm how to make it look a bit nicer again without too much effort ?
 

crassius

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wd40 and a rag will at least make it clean looking - many folks are OK with that

if you must paint, then keep a small brush and some extra paint to touch up flaked off spots
 

Island Racer

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wd40 and a rag will at least make it clean looking - many folks are OK with that

if you must paint, then keep a small brush and some extra paint to touch up flaked off spots
WD40 ..... I just googled that can came up with the following

Quote
I'm a bare metal guy with glass beading. Its all about the heat transfer and being able to spill gas without destroying paint. Once every few years I soak it with WD 40 and wipe it down with a clean Tshirt and let it evaporate off the motor next time I run it and it looks great again. This motor is about 5 years old since the last refresh of home glass beading with the heads dating back to 1996 since they were last beaded.
Unquote

So if i would sand down all partrs, degrease them and assemble the engine, then spray it with WD40 it would look nice ?

WD40 = Water Displacement 1 drop of WD40 will displace 40 drops of water ....
 

Island Racer

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wd40 and a rag will at least make it clean looking - many folks are OK with that

if you must paint, then keep a small brush and some extra paint to touch up flaked off spots
Ok i will try your idea, i will sand the whole thing down and clean it, then just spray it with WD40

Thanks for that idea ... Good one
 

crassius

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I would eliminate the sanding part - unless one polishes the crap out of it, it will show sanding marks.

back in 70s, I polished my GF's triumph motorcycle until you could see your face looking up at bottom of motor - took weeks with sand paper and 'diamond-white' polishing rouge - never did that again

aluminum can be polished to look like chrome, but discolors rapidly
 

Island Racer

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Jan 25, 2016
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I would eliminate the sanding part - unless one polishes the crap out of it, it will show sanding marks.

back in 70s, I polished my GF's triumph motorcycle until you could see your face looking up at bottom of motor - took weeks with sand paper and 'diamond-white' polishing rouge - never did that again

aluminum can be polished to look like chrome, but discolors rapidly
Ha ha, yes polished aluminium is terrible to maintain, i had a billit aluminium rear rim 250/40-16 and it was terrible to pollish

Ok i understood also no sandpaper or steelwhool then .... Just cleanup with a rag and WD40
Maybe the oxidation will be removed from the aluminium casing by that ...
 
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