KCvale
In memory of KCvale 1959 - 2019
The JS kit comes with all 410 sprockets and new chain.Also no one has replied about my chain thickness. Right now the sprocket is dead inline with the engine sprocket but the chain is so wide its really close to the jackshaft plate.
I looked on SBP's web site for a 415 gear to match your 415 system but they don't have one.
gasbike has a replacement 410 motor sprocket for $5.
http://www.gasbike.net/bike-motor-part-small-chain-sprocket.html
415 chain will run on a 410 sprocket but it will wander and wear odd and frankly 415 is a pain in the butt to work with, I'll take HD 410 any day for anything like this. Just swap the sprocket and be done with it as the kit comes with enough new 410 to do both JS sides.
The kit has a block spacer and a variety of drop in shims to get your left chain tight.
File the flat spot on the motor where the case seam is to get it all flat and level.
Check that your bearings fit easily into the JS housing, file if needed and always needed if you paint it like my example.
Also verify your shaft slides easily into the bearings, if not try filing the edge off the shaft ends.
Put the main block on the bolts and get them started.
Put your left sprocket on the shaft leaving a little nub as shown.
To make things easy 'butter' your 2 keyways, in short this means rub them against a file so all sharp edges are softened so the keyway looks like a stick of warm butter.
Then tighten the set screw that is not over the keyway, take it in and out a couple of times then remove the sprocket.
File a flat spot on the shaft where the set screw mark is so the screw will sit on the flat spot when tightened.
Remove both sprocket set screws, put the sprocket on with a black and 2 brass washers, then locktight the set screws in as this sprocket will no have to removed from the shaft again.
Now just drop in shims until you get your chain tight and of course make sure all the bolts are tight. You should never need a 1/2 link here!
If everything turns fine take the shaft with sprocket back out and mount your engine to the seat post.
Start as low as low as you can go with the pedal crank on and put the sprocket/shaft back in. Note I don't have a front mount on yet, the support shaft and 2 U bolts are holding the motor to the bike.
To make it easier on the right side just leave the motor chain off for now.
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