LH Colt restoration

[Paul_Linden]

Next step was to get busy on the head, where there were several issues to deal with. The picture below shows the head after it had the guides drifted out and was bead blasted. The dark patch on the surface that mates with the barrel was where I suspect it was blowing and the previous owner had attempted to cure this by tightening the head down. Not unreasonable, but the Colt has an alloy head and, yes, you guessed it, he stripped the thread in the head.

So first step was to lap the head - the picture below shows this it in an intermediate stage. The combustion chamber part of the head was also cleaned. In the picture you can see some scoring from where it had been previously cleaned with a wire wheel (oh, the horror!).

Now comes the fun part, drilling out the stud hole to take a helicoil insert (5/8" BSW if I recall correctly). Had to get the hole exactly in line with the axis of the stud it will take and perpendicular to the head. The pillar drill helps

[Paul_Linden]

In with the tap, and with an alloy head it goes like a knife through a low fat spread. Remembering to use the right procedure of forward and back turns, and taking it out frequently to clean the swarf.

Now in with the Helicoil (tm) insert. Are we having fun? Yes we are!

When the helicoil is in place, remember to snap off the little tab at the bottom.

Now we're all done. Just put the stud in to check the fit. Nice - it just slipped in.

[Paul_Linden]

So here we are ready to put the new valve guides in, and the one of the washers (cups?) which go under the valve springs, as the old one had split around its rim. You'll notice in the pic below at the top of the green tray is the drift for driving valve stems in and out. Home made from a piece of mild steel bar, the dimensions of the thinnest part are 7mm diameter, 25mm long, and the dimensions of the middle part are 13mm diameter, 110mm long. The thick head on it is just the bit to hit with the mallet.

Inlet valve guide in.

Both valve guides in - a piston eye view!

[Paul_Linden]

As new guides and valves are being used I thought it best to cut the valve seats true, but actually very little was needed.

So I then went on to lap the new valves in.

[Paul_Linden]

With the new valves nicely ground in, the head was thoroughly cleaned (twice) and the new valves and springs put in. It's at times like this that I get obsessive about cleanliness (but not godliness) as I really don't want any stray grains of grinding paste sticking around in the engine.

Now on with the trunion. This is the earlier version which doesn't have slots for the oil feed to the head. I note that Draganfly sell a conversion kit for this. If I'm going to put an oil feed on to the head, now is the time to do it.
It seems like a lot of effort has gone in to refurbishing the head back to a usable standard, and it was always at the back of my mind that Draganfly sell new Colt heads for about £50 plus VAT and P+P. My approach to this project is to refurbish every part of the bike whenever possible rather than just buy new replacement parts. But if I'd messed up and broken the head then plan B was to buy a new one!

[Paul_Linden]

Talking of cleaning things, i invested in this lovely little wire brush, just right for cleaning stud holes, like on the barrel, especially where they still have bead blaster's grit in them. I didn't buy it at a DIY chain or the local hardware store (yes I still have ones of those just around the corner) but online at a UK shop whose range of wire and nylon brushes is mind boggling - I didn't know there was so much possible variation.

And here is the barrel, cleaned and masked for painting. As an aside here, it was my original intention to get this stove enamelled. I could only find one place within a 50 mile radius that said they did stove enamelling (it said so on their website). When I turned up at their unit they told me they don't do it anymore.

So it was a can of spray on black exhaust paint that did the job. It has a silky finish, so it's not too bad. The flash on the camera gives it a reddish tint in the pic below. The other nice thing about this pic is that you can see the great job the reborer did.

[Paul_Linden]

Waiting for the crankcases and crank to come back from the engineer with the new main bush installed and reamed to size (something I don't have the experience or the tools to do). Might as well get on with something else, such as painting the rear number plate gloss black. When the paint is dry I can afix those stick on white letters I bought at the Shepton Mallet autojumble last year. Looking at them now I see I bought a mix of gloss and matt letters!

[Paul_Linden]

Another of those little jobs on my list was to make the wiring for the back light. This is the small length that plugs in to the loom behind the battery and runs along the underside of the rear mudguard to the number plate. A piece of 3 core seemed about right, and I kept the earth to give the lights a sporting chance of working. To seal the cable and make it aesthetically acceptable a piece of black shrink wrap was put over the ends.

This wire was fitted in place, running through grommets in the mudguard. The old grommets had rotted to dust and I tried to source replacements but failed. There are packs of assorted grommets available, but none were the right size. For a while it looked like I would have to do without, but then I found a grommet manufacturer in Sussex who makes exactly the right size. Unfortunately his minimum order is 1,000. So I used a 'close enough' grommet which unfortunately left a gap by the wire.

The solution was to fill the gap with 'liquid electrical tape', available from all good stores and some bad ones too no doubt!

[Paul_Linden]

August bank holiday weekend was chance to catch up with painting some of the tinware. Here we have the toolbox being being prepared for painting. The surface has many small pits which all need filling and sanding. A labourious and painstaking job.

I'm painting the bike with spraycans why? because I don't want to spend what a professional painter would charge, and because I don't have a spraygun, compressor and booth. The advantage to this is that I can do bits and pieces of painting as I go along. So at the start of this project I bought in enough cans to do the job so the cans are all from the same batch. However I'm beginning to see the limitations of spray cans, as it is near impossible to get an even application, the spray from the can comes out variable - sometimes its a fine mist (good) sometimes it's big droplets (bad). The result is below - a finish that looks like orange skin. No matter how many times I take this down to a smooth finish with fine paper the next layer of paint will come out the same.

[Paul_Linden]

The crank and crank cases were still at the engineers, so I set to work on the petrol tank. The pic below is the tank which came with the bike - not a pretty site, but maybe just about fixable. Plan B was to pick up a second hand Colt tank.

Finding a second hand tank wasn't so difficult, but the one I bought had been fitted to a different bike (a BSA?) and had the front lugs cut off, and new lugs welded on underneath. Apart from that it was in very good condition, with a few small dents and very little rust.
I cut the front lugs off my old tank and welded them to the replacement - the pic below shows the lugs being held in place before welding.

With the lugs on, it was just a matter of trying it on the bike - and after a little fettling it was a good fit. Then off to the chrome platers.