SOHC.co.uk Forums > CB500/550
Finally after too many years I'm working on my 500/4
UK Pete:
James i have not long been back from a nice hot sunny Mediterranean holiday, unfortunately i have got involved in a bigger project ( nothing to do with bikes) which has swallowed all my money and time, i will resume the sandcast and k0 projects late autumn
pete
matthewmosse:
Almost finished welding, I basically re fabricated all the pressed steelwork down the rear left of the frame, using a spare frame to copy. For convenience I used my Oxford oil cooled stick welder and did the welds mostly in 1 inch sections trying to keep distortion in mind. Getting the seams to look right is the biggest pain, last time I didn't bother, this time my workshop has more kit so I am able to get most of the z profiles fairly close to how honda did them. Just to crown this off I found the frame I am copying also has rust to the footrest hangers so I will probably be doing it all again soon for the k reg 500/4. Last repair like this I did was brase welded to better avoid distortion. This time I figured if I found it was badly out of true, I shall bend it right with a bit of heat.
matthewmosse:
Another 3 hours put in today, all welded and welds ground off, annoyingly spent an hour grinding out slag inclusions in a few welds and re welding, seems the rustier bits the weld metal just boils up and makes a porus mess, in the end I just cut out and let in big repair sections. I only kept a bit of th e original metal in any case, replacing each section 1 at a timecto try to maintain everything in position. If I did this again I think I would manufacture a complete subframe - doing both sides and the cross brace, probably faster than patching things up in the long run. Just crush tubes to add for the footrest hangar and indicator mount. Everything is nice fresh steel off a old golf course mower I recently bought off ebay, lovely quality steelbthat happened to be the right gauge, with the added irony of cutting up a machine that cost £10k new to fix something that was under a grand new. Next I shall wire bush in a drill clean it and bung on a few coats of red oxide and satin black paint. I will also fill the new frame sections with spray grease before welding in the crush tubes. What was alarming about all that corrosion is externally it looked ok, it was only a pointy hammer thar revealed the thing was bean can thin from internal rust. For some reason the computer won't let photos be saved smaller so they must wait.
matthewmosse:
Finally started on applying paint. Went wire brushes in a drill route, seems the frame had previously had powedercoat, where this had lifted I found a few rust traps but most was in good order outside of the reat subframe area so I scrubbed all the thing up to give a good key and have applied a rather nasty looking coat of red oxide primer, it does rather well on killing rust, and once thinned gives me the best chance of getting some corrosion protection inside any joins which is where water let in by capillary action seems to have done dammage. A top coat of gloss black or 2 and I shall then start the rebuild process. Noticed the swing arm has drain holes, will be filling these with thinned red oxide then draining and once dry, a bit of old oil. Keep the rust fairies at bay. Good thing about this cheap and fast way of painting is it will be easy to touch up if dammaged.
K2-K6:
Sounds like you've got the frame back up to scratch Matthew, my dad always painted everything with red-oxide when I was younger and it seemed to last for ever.
Image sizes, alot of cameras have a resize option in the menu and you can bring it down to something like VGA file size without having to bother with changing it on a computer at all, be good to see some photos as you get along.
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