while it took a while to load, it did work...
see the bar just above the box where you type a reply/start a thread? 3rd from the end is a picture of a tree. try adding pics DIRECTLY, cus there is NOTHING worse than reading old threads where the site has vanished, leaving a blank spot of uselessness... (i look up a lot of things and that is one thing i DESPISE! critical information either requiring a register and login, or...that blank square with a default pic of a camera or some message about user having removed, or simply having to be redirected to another site in another tab and oh my... and you "might" have to resize the odd pic or two...
) anyway!
you got your chain off without removing the master link! neato!!
(please dont state the obvious :wacko: )
im sort of getting the idea your actually having a hard time threading the new chain onto the sprocket, not really having a "fitment" issue at all. 415 should be fine! same as 420! the roller diameters are correct, there should be enough space on the engine to take the wider plates, etc etc.
at least, those sizes work for the rest of us?
sprocket, while its had some use, isnt beyond the point of no return.
so. threading a chain on... you got the first step done, take off the cover.
remove opposite cover. the one over the clutch and gears.
now, you can either remove spark plug or loosen off the clutch mechanism to make it easier to turn the engine over.
and there you go, the rest is usually pretty straight forward. somehow you need to rotate the sprocket and keep chain from jamming in the case as you do it.
you can thread a chain through without popping covers, just pull in the clutch, stand the bike up on the rear wheel, and zip zip... otherwise it has an annoying habit of bunching up inside the case JUST as its about to come all the way through. its a matter of experience, using your head combined with this new theory that gravity isnt ALWAYS a b!tch
you wont EVER be able to just slip the chain over the sprocket "side on", even with a nice thin bmx chain... is that what you tried doing? huh? be honest now! we wont laugh! well, we will, but who cares?
]ive often contemplated grinding away some of the case just so i can, but i dont really change chains that often....