chain sizes

I have done research but can't figure this out.

I bought a sprocket from andy at kings sales and service. I placed an order with SBP and asked if they had a 410 chain laying around they could sell me. They said no and that all they use is a 1/8 bmx chain on their bikes. So I got a 1/8 chain and it fit around the sprocket just fine but wouldn't fit around the drive gear in the engine. It's like the pitch was wrong or something. After the chain would go around 2 teeth it wouldn't work anymore. I don't understand how the 1/8 chain could work on one sprocket and not the drive gear when the 410 kit supplied chain would work on both.

Anyways I went to a local tractor supply and they only had #40 and not #41 chain. I was wondering if someone could tell me why the 1/8 chain wouldn't work on the drive gear and also what is the difference in chain sizes. For example what is the difference between #40 and #41 or #41 and 410 etc...

Thanks in advance guys

Thank you guys. That is a great chart. Ret I don't have the ability to machine. It looks like the #40 is too heavy duty since the chain I am using now barely clears the tire. I will hunt for a #41. No Ace hardware around here.

By the chart it says that #41 is 1/16 wider than the 415 chain and the #40 is 1/16 wider than the #41. The tractor supply here said they can special order it but don't stock it.

You know when I said tractor supply I meant a locally owned place where they fix and sell tractor parts. I think you guys are talking about a chain store called tractor supply. I did a search and there is one 15 minutes away. Civilized are you saying they carry a chain tensioner too. Is it spring loaded or like the ones in our kits?

spring loaded tensioner. That would be awesome! That way if the sprocket is a little off center the chain won't have tight spots the spring will keep the chain at the same tension all of the time. This would also make the chain last a lot longer.

I went to that store and they were out of the tensioner. I got the spring. Then when I got home I checked their website. It said they are out of them online. I called all of the stores within a 60 mile radius and they were all out. I wonder why it is so hard to get. Hopefully they will get them again.