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Post by aaroncaton on Nov 23, 2014 10:37:51 GMT
Hi All, wondered if anyone could help me on this? I'v currently got my 1979 cb400n's engine stripped down, and im looking to restore the crank case halves back to original finish? i understand its meant to be bare aluminium, but not polished does anyone know how to achieve this?
Aaron
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Post by scania on Nov 23, 2014 10:48:26 GMT
I would imagine that polished would be more resistant to corrosion than bare, but I don't know much about this. One of they guys here is a Metaluroligist or something like that. (he is not into metal music, rather he knows all about metals!)
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Post by jonnyboy on Nov 23, 2014 11:12:40 GMT
My advice to you is to take some nice close up photos of your bike post them up on here and let the "anoraks" sorry! professionals do their thing..........if you want it original you are in the right place  |
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Post by aaroncaton on Nov 23, 2014 13:45:46 GMT
Thanks jonnyboy, il get some photos today and post them up later
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Post by scott on Nov 23, 2014 14:27:21 GMT
I would say the best way to achieve an original type finish is to bead blast the crankcases and then go over thing lightly which scotchbrite. you'll get a finish like this which wouldn't corrode if looked after. And all I do is keep my bikes clean, never have polish it or anything.  |
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Post by Deleted on Nov 23, 2014 16:51:07 GMT
Chop it up and make into a cafe racer ! !
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Post by aaroncaton on Nov 23, 2014 20:33:10 GMT
Cheers for the help Scott! that finish is the exact one i'm looking for!  il give it ago as soon as i get hold of some glass beads! |
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Post by Deleted on Nov 23, 2014 20:43:10 GMT
Hi there and welcome to the forum.
I was going to suggest bead blasting. I saw a CB250N engine last year sitting on a table inside the halls at Stafford that had been bead blasted and it looked really clean.
The only reservation that I have about it is that it had scarred the finish a bit - maybe it is quite a harsh process?. Originally, the middle crankcases on these bikes were painted with a silver paint, as with a lot of Honda Motorcycles of the time - side casings were sisal polished and then clear lacquered from new.
So to reiterate - I think bead blasting looks great but may not be everyone's cup of tea.
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Post by scott on Nov 23, 2014 21:04:55 GMT
The finish from the glass beads depends upon how badly the engine was corroded before blasting Nick, it it was badly corroded you will get pitting marks left in the alloy, as is evident in my pic above. My SS50s on the other had have come up nicer...if they were originally painted then bead blasting and then painting would be the way to go...   |
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Post by paddlesat16 on Nov 24, 2014 14:24:18 GMT
I think soda blasting would give the correct look as it's not that harsh.
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Post by rich on Nov 24, 2014 15:32:54 GMT
lovely pics scott...........how was the c series eng oil pump drive when eng was stripped.........have seem many of them with a "wavy line" where the drive teeth used to be...........consequently with the centrifugal oil filter almost completely blocked solid......absolute minimum oil for the big end, which survived.....most of the time......however a couple of c90's with pistons hitting the head due to b/end failure.........happy days....... |
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Post by scott on Nov 24, 2014 17:50:04 GMT
Had a big end fail on my brothers SS 4 years back, the bugger wasn't keeping an eye on the oil level and ran it off the dipstick!! They all seem to use a bit of oil, even newly rebuilt motors. Yes I know exactly what you mean about the centrifugal filter getting blocked up, I don't think my 4speed had ever been cleaned out in 30 odd years when I open that up it was full. That was the first thing I checked on the C50 when I first got it. This engine was built completely of parts, I started with a bare set of crankcases and had to source everything else. actually runs a Chinese pitbike gearbox with SS50 selector drum to retain original shift pattern.
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il give it ago as soon as i get hold of some glass beads!