LH Colt restoration

[Paul_Linden]

This is the sliding gear on the layshaft, the one on the left is what came out, and the one on the right is what it was replaced with. No need to explain why - the old one is so worn I'm surprised it stayed in second gear at all. The gear on the layshaft that this one engages with was also replaced.

So now all the gears, bearings, selectors etc were cleaned and checked it was time to start re-assembling the gear box. The two bearings were in good shape so I didn't change them (if this was the crankshaft I'd change the bearings whether they needed it or not, but here it's less of a gamble). Both bushes in the output sleeve gear were replaced as they were worn. The pic below shows the two shafts together, with the re-splined kickstart shaft.

And on with the selector forks.

And then on with the selector plate. The position the plate is shown here is the same as in the exploded view in the parts manual. However, it can go in one of two ways - just flip it over for the other orientation. This pic (ahem) shows it in the wrong position! Somehow I got it the wrong way around, and went with that as it was the same way as shown as in the parts book. Of course it didn't work when assembled, and after much head scratching I looked back at the pics I had taken and saw the problem. Hey Ho! Many a slip twixt bench and finished box.

[Paul_Linden]

Now slide the assembly in to the half casing. The photo seems to show rust patches, but I think that's just an effect of the flash.

The cluster is a good fit in the casing, with the mainshaft and the layshaft (upper and lower shafts respectively in photo below) just sliding in to their respective holes. You can see where the bolt to hold the selector plate goes through the casing and through the hole in the selector fork (not quite aligned in the pic below).

Then the nut goes on the end of the mainshaft. I found it easiest to torque it down when the whole box was assembled.

Next photo is of the selector stop arm. This spring loaded stop arm sits at the back of the gearbox and the head of the arm engages with notches in the selector plate. So when you change gear the selector plate is held in position, and the gear selected remains selected. The bottom one is new, the top one is the old one being replaced. The old one is so worn that I suspect that it didn't stay in gear to well.

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Putting the new arm on its pin bolt.

[Paul_Linden]

Then on with the circlip that holds the arm on.

And behind the arm goes the spring which tensions the arm against the selector plate edge. After a dry run assembly I found it was easier to put the gearbox together without the spring, and only drop the spring in to position at the very end of the assembly, through an access hole at the back of the casing.

On with a new oil seal in front of the mainshaft bearing.

And don't forget the circlip to hold it in.

[Paul_Linden]

The two halves of the cases were then ready to join up. Despite having two pins which align the two halves, this was a little tricky, as the mainshaft, selector fork rods and layshaft all have to line up and slot in to their respective holes. For some reason it was easiest to do this while neutral was selected. With the two halves of the box together, attention was turned to the outer case. In the picture below you can see the end view of the selector plate on the LH side, the clutch rod worm - middle top, the kick start shaft coiled spring - middle bottom, and the hole for the gear lever shaft - RH side. For info, the two screws top and bottom are holding the two halves of the case together as the plate stop spring acts to push the cases apart - not something you want when you are testing the gear selection.

Then on go the gear selector shaft and arm, with the U shaped spring that returns the gear lever to the middle position.

So here is the whole gearbox together, on a dry run, just to check everything is working as it should.

And here it is on the bike viewed from the RH side. This is the final build as you can see the orange gasket goo smeared on the paper gasket between the joints. The gear lever is on and all 4 gears select OK. The kickstart clamped on all right and turns the mainshaft as it should, although the real test will be when kickstarting the engine for real. This is the undersize kickstart that I adapted the kickstart shaft to fit. I couldn't source a replacement kickstart shaft and as the old one was stripped and only of use as a pattern I didn't mind adapting it.

And on the LH side I dropped on the collar, sprocket and lock nut, using the old chain to lock the sprocket while I tightened the nut. So job well done, take the rest of the day off! Now the weather's getting better I will start on the engine. watch this space!

[bsmart]

high paul , got to say your bikes lookng good , your photos are going to prove handy when i get round to doing mine , keep up the good work

[Paul_Linden]

Strewth! Was it really in March when I last posted here? Well I have been working on the Colt, so I guess it's time to post a few pics and keep you all updated. Over the last few months I've been working on the engine strip down and clean up ready for the rebuild. The pic below is the timing case. The screws holding the points plate are out and the central bolt holding the advance retard unit is out.

The best way to take the advance retard unit off is to drop a bar (about 7.5 x 80 mm) into the central hole and then put in a bolt on the inside thread. As you screw the bolt in it will push the advance retard off the taper. Can you see that on one of the arms on the AR unit the circlip is missing? It's held on with a piece of wire

With the advance retard unit off the six screws and the ally case come off, revealing the valve gear and oil pump driving gear.

[Paul_Linden]

Off with his head! And this is the sight which greeted my eyes after the decapitation. Not very pretty, but the copious amounts of oil which I'd squirted into the chamber two years ago when I bought the bike had helped prevent it rusting solid. Some of the head studs stayed in the head, some unscrewed from the head as the nuts on them were seized, and one just dropped out.

And below is what the head looked like. The stud hole in the bottom right is the one with no thread. Helicoil insert time, unless there is another way (I'm open to advice!). The head gasket is composite, with copper and some sort of fluffy (asbestos?) filler. The blackened area around the bottom right is where it was probably blowing - no surprise really.

After lifting the barrel off I found this, which doesn't look to bad, except...... It's an +0.060 piston and the barrel is worn out, so nowhere to go with that. Put a sleeve in the barrel or buy a 'new' one. Oh dear this is getting expensive. Interestingly the piston has has the word 'front' stamped on it (on the same side as the split in the skirt). Whoever, put this piston in chose to have it pointing to the rear

[Paul_Linden]

Here's a view of the bottom of the cases. Nothing much to report here except a broken stud on the sump, and a very chewed head on the drain plug. The two bolts holding the oil pump in were difficult to undo because of their size and position close to other parts. Eventually they came out and I've now sourced some allen bolts to replace them.

Next was the timing gear on the end of the crank. This was a right little begger to take off It was like it was welded on, and none of my pullers worked. Eventually, lots of heat and a newly purchased puller did the trick. You can see the discolouration from the heating. Part of the problem seemed to be - but I'm not 100% sure - that the woodruff key moved a little and acted as a wedge to hold the gear on the shaft.

Once that gear was off it was off I was on the home straight and only splitting the cases was left to do. Voila! Job done, time for a beer!

[Paul_Linden]

The barrel I took off was +060" and worn out, but I found and bought a worn standard barrel and a +010" NOS Hepolite piston kit. I had the barrel (pic below) blasted to clean it up, and it is now at the engineers (a local chap with two Rudges) being bored out. When it comes back I'll just need to paint it black and it'll be good to go. Is stove enameling on barrels still the done thing? A BSA owner told me to paint it myself with B&Q black barbeque paint, which I guess would work.

I also had the head bead blasted. It's now ready for cleaning internally, new guides and a helicoil insert for the stud. The photo also shows a crack in the fin above the spark plug hole. This doesn't extend beyond the fin, but there was a moment of gloom when I spotted it for the first time.

The cranks not too bad, no up and down movement, but the side to side play is enough. So while it's out I can put in a NOS con rod and big end bearing. Interestingly the NOS big end came with a double row of rollers, while Draganfly sells big end rollers that are twice as long and only one row goes in the big end. Any clue as to why there are different big end bearings - is one better than the other?

[Paul_Linden]

Started cleaning the cases, ready for new bushes. This is the timing cover and its new bush. There is some play in the old bush, but I don't know how much play is acceptable (0.002"?). Not owning a press and reamer this is another job I'll leave for the experts.

Inside shot of crankcases - the main bearing is new, just the bushes need to be replaced. The broken stud in the sump drilled out all right and the remains came out without damaging the thread in the case. New stud went in all right, but the non-threaded part was longer so I had to cut a little more thread on it. The old hard gasket goo between the cases shows up as red in the picture. This is what's left in fine grooves of the machined faces - its difficult to remove, so its a case of clean off what gets in the way, but leave what doesn't.

Other side of the cases, cleaned but not polished.