In the first episode of this series Dave introduced us to his 1967 BSA A65 Thunderbolt,
and showed us the starting point for this low budget classic motorcycle restoration project.
Today there's a few more jobs on the list to move the Everyday Bike Project along. These videos are
designed to give you an idea of just some of the work involved to put a bike like this back
on the road. Of course we always recommend you consult your owner's manual to check the details
for your particular machine. Let's get on with it. [Dave] Right, just going to bring you back up to
speed on where we are with this engine from last time. We've put the gearbox cassette back in. It's
quite easy to put in. The detent is at the back. It all lines up properly, it's easy. When we come
onto the drive sprocket, I've left the old one on this pair of grips here. It's a little trick.
When you've got the bike in the frame and the chains on the sprocket,
it's quite easy to hold the back wheel, and not let that sprocket turn. But when the engine's on
the bench you want to hold that sprocket and do the nut up tight. These adjust the mole grips,
and it works quite well to actually clamp these. Get that nice and tight, I'm just showing you now.
Now you'll see that we've got the nut there with the tab wash already bent over, but to show you
how easy it is with a box spanner, literally on the nut and you can get good leverage. Hold this
because you're on the bottom part of the alley on the casing here. But then you can get a really
good pressure on this. Use a long tommy bar in your box banner and pull that up really tight.
Then you only need to, just use one of the flats to bend over your tab washer.
Rather than people, what they tend to do, it's basically if you haven't got one, they knock
this round with a cold chisel. But you can't get that tight, and also you muller that nut.
Just get all your screws back in finger tight first,
and just wind them up until they come into the counter sink.
Because we've taken this cover off and put it back on, it's already got some Wellseal on there
because there's no gasket behind there. We've just taken it off so we could show you the nut behind.
You want a good screwdriver, these are quite old these screws, I've had to face them off a
little bit. But just tighten up, and you don't want to over tighten. But a good screwdriver,
and just give them a good, good turn, and go alternate sides.
Because they go into a taper, so you just want to be nice and tight.
Now the plate's back in place, we've just got to put on the main shaft clutch boss adapter.
Just will show you, when I got this bike and we went through the bits and pieces, I did find that
the original taper is quite badly worn out, and it's where probably the nut was loose and it's
moved about on the shaft. Now if I put that back over the keyway, it's a job to tell but it doesn't
hold onto the taper. Now I've been lucky enough to find all the bits as new, another clutch centre.
And when that's back on the keyway that really is a good nice tight fit. We can't put that on yet,
we haven't got that far. But there has to be a thrust as well. There's a thrust washer behind
the back of the clutch. But what we're going to do before we do this, we're going to put
our pistons on and get the barrels built back up. Then we'll put the clutch together for you.
But I just wanted to show you that. Always make sure that isn't warn before you put it back on.
Because if your nut was loose, your centre nut on your clutch, because it has a washer afterwards,
that goes on. And if that was a little bit loose there's a good chance that key has been chattering
in that centre, and you might have found the whole clutch was wobbling about quite a bit. So,
always check the condition of that clutch centre. I'm just going to make sure with people they know
where they are with this. Now, we know we stamped up 20 thou oversize. We got two sets of new
rings. We put the top ring in the bore here. It's so important to have the right clearance. There
has to be clearance, there's got to be a ring gap. Now, this is actually marked up in the book,
if I show you. It's got a fitted gap here. It's .007 to .012, that's 12 thou. Now I've
got 12 thou here. If it's slightly over, it doesn't really matter. But you've got to have
the clearance. So that's 12 thou. We've got a ring gap here. And I'm just going to put
the feeler gauge in that gap. Just a little bit grippy. Now that's quite serviceable. It's
important to make sure that you have got the right rings, so always take a ring out of the packet,
stick one in the bore, and just measure it up. If you're in any doubt about the size of your piston,
go to somewhere, to an engineering firm, and they'll measure your bore up.
So you can do a vernier gauge. You can put your gauge into your bore and we can measure this up.
And we're 75mm bore. But it's slightly oversized now, 20. So we've gone 74.11
But that would give you your reference. You be able to check in your book to see what size bore you are.
If there was a lip in this bore before we honed it out and you were scoring,
we wouldn't have messed about. We'd have gone from 20 to 40 thou,
and we'd have gone for a new set of pistons oversize, and got this bored out.
Because I didn't have a lip, and it was just like superficial scuffing, a little bit of a seizure,
we just cleaned it up. And that's why we got away with new rings. We're not spending a lot on this
as we've explained before. But there we are, we've got a new ring in there. Good gap. So we're going
to put the rings on the piston properly, then we'll put the pistons on the rods, and put the
barrels back on for you. Start off with the bottom ring, which is the oil control ring.
These are coiled rings. It has a device in the centre here.
Stops the oil from coming past the ring. So we put this on first.
This has got an expander in it, somewhere around here. I will show you. There we go, on the rail.
So we just open it up on the rail, slip that over, find the groove, and close that back up.
Now this ring, we're looking for a mark top or bottom. This one is the same.
But we'll check on those, you'll find that those will show you top. Just slide this over.
There's a groove in the centre of this ring for that special device to sit in. Not quite there.
There you go, that one's in. So that's the bottom ring, oil control ring. Mixed with it...
you need the second ring.
Now when you get a packet, it does show you sometimes a reference. This shows you like a
groove of the piston. Well this one now shows you the second one. Always do it in order.
Now on the ring it's marked. There's a mark up here, top. It's so easy to grab a ring stick it on
and think, 'I didn't check to see if it was top or bottom.' But top. That's tapered normally. There's
a taper. So we slip this on, you don't need to use oil. Slip it on. Don't pull it out too far.
That one's in. Top ring has another mark.
It doesn't say top on this but it has a little symbol.
Just open that out. There you go. Now someone said to me just now, the cameraman, about the piston.
Some pistons on two strokes you'll get a peg. This little pin. And you have to make sure that the
ring gap comes where the peg is. On four-stroke, you don't get that. The rings are allowed to move.
The reason on a two-stroke they don't, is because you have transfer ports. And if you were to look
at a cylinder bore on a two-stroke, there'd be cutaways. And if that ring was to move round,
it could end up with the gap running over an open window, and that ring could get caught up and
it would snap. And that's why you have a peg on a two-stroke, so the ring can't rotate. Four-stroke
it's just a bore, and the rings will move a little bit. They won't move very far. Right,
we're ready to put the pistons, both of them, back on the rods. So what you need to do... A lot of
people are driving that gudgeon pin cold. Best to heat the piston up. Either with a blow lamp,
just warm up a little bit so you can push the gudgeon pin in easily. Or you boil up some water,
and submerge the piston in that, just to expand the aluminium so
the pin moves easily. At the moment you see it's quite tight, so we're just going to warm it up.
You won't need a lot of heat, it's just to
expand the aluminium a little bit. Just mind your hand. You can do this obviously not holding it.
But it's easy this way. I just want a little bit of heat around the skirt of the piston.
I'm doing both sides here because it's got to push through to the other side.
I'm just going to check that and see if we've got any movement. Yeah,
it's moving easily. So we're just going to make sure we've got a little bit of lube in the top.
Make sure the pistons are round the right way.
That's in. And what we've got this side, we've already got one circlip in.
So you're able to push that in with your finger. Right in as far as it goes. Then we've got to
put the other clip in that side. But you see by heating it up it makes it nice and easy. Now,
if that was cold and you had to drift that in you can so easily damage something. You've got this,
and you could bang it against one of the studs. But by just pushing it in,
you know everything is fine. And it's gone straight through the bush, small end bush.
So we're going to do the same with the other piston, and put the other clips in at the end.
You just need to give this a gentle tap just to finish it off.
Yeah, when you come to do this job, you don't have to rush it, but you will lose
that heat fairly quickly. So try and get it in as quick as you can. Get it centred. Get it in.
If you have to tap it the last little bit like I had to there, it's not a problem.
But don't forget you've got to put your two circlips back in now. Okay,
so we've done one circlip, but we're going to put this one in to show people this one,
this side. So like I said before, you need to use your thumbs here quite a bit.
Get it in where the cutaway is in the bottom part of the piston. And you can get that first
section in, and sort of twist it. Get your nail underneath it, like I have there.
And if you look, I'm just on the outside. I'm not in the groove yet.
And carefully with a screwdriver, a blunt screwdriver,
just push it home. So just make sure, push it down into the groove. First one's in.
You can see this is still hanging out. And just be careful how you push it in.
And let's just make sure it's home. And we just try and push it away from the...
the groove.
You have to lift up that part, and there we are. That's home. And just check all round.
There we go. Just a little note, when you put that circlip back in,
it's all a matter of feel really. So using your thumb, your thumbnail,
you're don't want it to ping out. You can use a screwdriver. Don't use anything sharp really,
not a good one, use once a bit rounded off. What you don't want to do is slip across your piston,
across the skirt on the outside, and put a score mark down it. So really just be careful. I've just
used this just to guide it in ready to show you more than anything else. Because I managed to
get it in, and again just push it down in. If you was to mark it inside where the circlip is,
that's not a problem. But you don't want to put up any marks on that piston. Just be very careful.
If in any doubt use something that's plastic maybe. But you just need to push that in. Now that
is what we call, you've got circlips,
and these are called snap rings. This is a snap ring. It doesn't have the little open eyelets
on it like a circlip, when you use circlip pliers. Those I do change quite regularly.
But these snap rings, these are sprung steel. And once they're in, they're in. They don't move,
they won't come out. Circlips, because they're squeezed quite a bit, they can slacken off,
but these are okay to use again. I know people say you should replace them but,
you know, all in good order, it's nice and round. Right when we're doing anything like putting the
pistons back on, the rods, putting the circlips back in the end, or snap rings as these are,
always stuff a bit of rag in the bore, in the crank case rather. And also when we put on the
barrels as well, when we start it off. If anything drops you don't want it going inside there,
so it's just a little reference. Now, when we were just pushing in this little snap ring
circlip, if by any chance you did slip and you put a mark into the piston, it's not the end of
the world. Don't want to do it, but if it's just a score mark on the inside just get some wet and dry
and just go around with it. And if there's a mark on the piston here you scratched it,
don't be too alarmed with it. Just rub it out. Go up and down, just take the high
spots off. But you shouldn't be doing that, if you hold your screwdriver very close,
you're only just using it literally just to push that in. You're not holding it back here.
You're just holding it very short. It's just to give you a little aid just to push that in.