Not all the 415 chain is created equal. I tried a Regina 415 chain from a local motorcycle shop and it would not work. The pin spacing was correct but the bushings around the pins were bigger thus the spacing was smaller and it would not work around the ten tooth sprocket.
I read some days ago on this site about being sure to buy a new chain for the engine right away. can anyone tell me who I buy this chain from? I see from this post that all chains are not the same. My link bust off today from the Howell engine and I rather invest in a better chain now. Been a great help this site. Thanks to all.