Well, that has certainly opened a discussion, I did realize that all chains are not the same, I have down loaded lots of charts about chains
of good old Google. And I have purchased a couple which do not fit (they fairly cheap) and I have gained some useful hands on experience.
Which is what it is all about.
My last experience was when I was seventeen and a had BSA Road Rocket, went to the local bike shop (where I worked) and bought a spring
link and guess what a perfect fit. Life has got complicated.

Hello All,
I have a question about a spring link for the rear chain, what size should it be.
The details, the chain is a good fit on the rear sprocket, but it has 2 spring links because it has a half link fitted.
The original links that came with bike are not the correct ones, the pins are much too long, so I ordered a 420
spring link but, the pins are too small while being the correct size for the chain. I have now ordered a 428, so
while I am waiting I thought that I would ask the question.
It has been over 50 years since I last bought a motorcycle spring link.

George.

I think most of you will know that I am restoring a D3 Bantam, my question this time is.
Does it matter which side the toolbox and the battery box are fitted, seen plenty of pictures and they are on different sides.
When the bike left the factory each one was surely on the same side?

Just one thing before I pack this thread in please, my engineer has got my barrel and piston and I am picking them up tomorrow but one final question as a matter of interest.
Is it normal that when a cylinder is re-bored the new piston is slightly domed, I ask because Cox & Turner from whom I purchased the new piston and rings said it was a standard flat top piston at 0.040", but it is not, it has a very slight domed crown, or at least not as flat as my original piston. If you know what I mean.   

rhyatt, we were talking about automotive engineers and I said that there used to be, well I went to see them today they are still there and they now take up both sides of the road and they said they couldn't do any automotive stuff because they don't have the tooling to do such small work, they now do heavy industrial work. How times change.
Anyway, I went back to basics, I put a pair of inside callipers in the bore and fixed them, when I went across the tips of the callipers with the verniers they measured 61.76mm.
I am therefore fairly confident to say that they are +10 over standard, and I compared the head with FAQ's on the other site and I am happy that I have D7 barrel and head.
Thanks for your advice.   

ryhatt, that's what I wanted to ask you, in one of your previous posts you said the gap between piston and bore should be 0.004" or 0.005",
which mine is already, if I get the barrel re-bored to +20 (from +10) that 4 or 5 thou gap will be a lot more?

Just measured the bore and it reads,  61.76mm the standard bore is 61.5mm. The difference .26mm equates to 0.010".
The piston I have that fits the bore reads,  0.020 with the letter R stamped on the crown, the piston has a domed crown,
unlike the original piston which was flat across the crown.
Totally baffled.

I ordered the rings from as you instructed me and he certainly knew he was talking about.
I now think someone has just stuck any old piston in a used cylinder that they had and the piston does not belong to that cylinder.
That is the problem, you take your chance when you buy from an autojumble. Even if the person selling tells you they match.
Can I rub the end of the rings with fine emery to gain a few thou.