Guide to Roller Chain
There were many different manufacturers of minibikes back in the 60's and 70's but most of them used one of three different size roller chain. You may see chain size referred by what pitch is has. The pitch is simply the distance from pin center to pin center. If you need new chain and your having difficulty determining the correct size that you need. Here's some information that may be helpful.
Number 35 Chain: Pitch = 3/8" | Roller diameter = 3/16" | Roller width = 3/16" | Pin diameter = 1/8" | Tensile = 2,100
Number 41 Chain: Pitch = 1/2" | Roller diameter = 5/16" | Roller width = 1/4" | Pin diameter = 1/8" | Tensile = 2,000
Number 40 Chain: Pitch = 1/2" | Roller diameter = 5/16" | Roller width = 5/16" | Pin diameter = 5/32" | Tensile = 3,700
Number 35 was uses on most all 4-5-6 inch wheel minibikes while 41 was used on larger minicycles such as Rupp Roadster II and Speedway. Number 41 chain will not run on a number 40 sprocket. Number 40 chain will run on a number 41 sprocket but it will be wider than needed.
Space chain is handy if you have sprockets that don't align properly. On space chain the outer links are just a bit wider so there is a small space between the inner and outer links. This space allows the chain to flex side to side much more than standard roller chain and will not run off the sprockets as easily. Although space chain is available in most sizes it is usually not a stock item and may be a special order.
We have dozens of chains and links in our ebay store.
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Happy Trails, Chuck at Valley Farms