Engine cases

[Dave487]

I've finally got around to stripping the engine and a few gremlins have popped up, mostly caused by physical abuse but no excessive wear so far considering the 61k mileage.

What I need to know is were the cylinders and crankcases originally paint or lacquered finish?

Mine has been very poorly silver painted, probably with a rattle can and the alloy underneath looks  dark grey.

It's going to need a lot of preparation to get it looking right and I'm not sure whether to try nitric acid solution or have them professionally blast cleaned.

Any help on this would be appreciated.

[Nurse Julie]

This link may be of use
http://www.sohc.co.uk/index.php/topic,10783.msg78781.html#msg78781
Originally the crank cases were painted and lacquered.

[Dave487]

Thanks for that Julie.
 I think it'll have to be a professional clean. I tried the cylinder head in the dishwasher and I'd probably been better with a bar of soap and a toothbrush (b*** useless.

[kettle738]

Just the top crankcase and the rocker cover had silver paint......(and the clutch cover, sprocket cover and alternator case of course)......... everything below the seam between the crankcases was plain alloy.

Never been too sure what if anything they put on the cylinders and head......it looks like nothing at all, but I'd be interested to know for certain.

Mick.

[Nurse Julie]

Just the top crankcase and the rocker cover had silver paint......(and the clutch cover, sprocket cover and alternator case of course)......... everything below the seam between the crankcases was plain alloy.

Mick.

How can that be, the top and the bottom wouldn't match?

[kettle738]

How can that be, the top and the bottom wouldn't match?

The top and bottom don't match, it's common to other Hondas......CB450 being the first that springs to mind. [ Guests cannot view attachments ]


If the attachment works......this is a 600m from new engine that had been stored since 1978, it shows quite clearly where they applied paint [ Guests cannot view attachments ]

Mick.

[Nurse Julie]

Yes Mick, I can see the difference in colour now. So on the 2nd pic, the 400/4, what's that pickling on the bottom crank case, is it a lacquer?. It must have something on it, as after all those years I would have expected it to be all oxidised if it were bare alloy.

[kettle738]

Don't flame me if I'm wrong but I believe that is just traces of crankcase sealant that have become far more obvious with age as they have discoloured...they would probably wipe off with a bit of acetone...

The engine was stored inside a centrally heated house hence the lack of corrosion.....the downside is it had a thick layer of grime, dust and carpet fluff etc that had got everywhere.....when I blew it off with an air line inside my garage I instantly regretted it.

The engine on my own 4,100m from new 400f is identical.....it's a shame they didn't finish the cylinders and head because they tend to look pretty grotty with no obvious way of improving that doesn't involve paint or dismantling....no idea why they didn't as the entire top end of plenty of other Hondas were painted with no problems.

Mick.

[Dave487]

It must be a Japanese thing because the Yamaha TZR250 that I restored last didn't have the bottom painted even though the top crankcase and barrels were painted black.
If Trigger paints and lacquers them all over then I think I'll do the same as I doubt that all the corrosion can be polished out.
This is after repairing all the stripped threads and broken bolts etc. caused by a PO. I think their tool kit just consisted of a stone axe.