Jackshaft Shift Kit Questions for anyone thats allready installed one

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.
The JS kit comes with all 410 sprockets and new chain.
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.

JS8-13PantParts1.jpg


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.

JS8-13PantParts2.jpg


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.

JS8-13PantParts3.jpg


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.

JS8-13PantMount1.jpg


To make it easier on the right side just leave the motor chain off for now.

(continued below)
 
(continued)

Once the engine is back in don't bother with the engine chain, it will be easier to work the other side with it off.

JS8-13PantMount1.jpg


Now you start playing with getting the right JS sprocket lined up with the chain to the outer BB sprocket.

Once you have the distance right screw the set screw that is not on the keyway down a couple of times to mark the spot, pull the shaft and file it like the other side and reassemble with locktight.

JS8-13PantMount2.jpg


Be sure to get your spacer washers between the clutch case and JS frame and tighten that 3rd anchor point.

If you have forward cranks like this Macargi you may find your chain wants to hit the bottom of the motor like this.

JS8-13PantMount3.jpg


With a little more motor height and sometimes you can just grind the that cover plate down to the recessed bolt and it fits under fine like this.

JS8-13PantMount4.jpg


Note all of this was done with no front mount concerns as it is pretty easy to build a good front with right parts.

Front continued below
 
(continued)

Once the motor was where it needed for everything to function I had a pretty big gap from front of motor the front bar si I just use an left over shift kit block and a couple of those lame 'drill the frame' front mount plates to attach the SBP front mount to get close.

JS8-13PantFront1.jpg


The kits spacers and muffler clamp and we are secure up front.

JS8-13PantFront2.jpg


JS8-13PantFront3.jpg


That black cable is my replacement CDI wiring by the way.

You will no doubt need to raise your motor for the right side chain in short order but even 2 miles pretty much gets everything broke in, the trick is getting everything to that last JS sprocket perfect, from there it is all easy.
 
Well presented photos KC

I have never tried converting the engine output shaft sprocket from 415 to 410, but i do know that 415 specification heavy duty chain doesn't stretch as fast as 415 light duty chain.

Never have i had a reason to down spec from 415 to 410 chain.
 
You should never need a 1/2 link here!

I find that statement to be partially true because the dimensional difference between engine manufacturers is not consistent and even dimensional differences between engines of the same manufacturer can be surprisingly inconsistent.

Most of my engines required 1mm to be removed from the rear engine mount to achieve a perfectly flat mating surface but i had one engine where the mounting face tab was significantly taller and required 3mm to be removed, thereby allowing the jackshaft frame to be placed in somewhere near an acceptable (centre to centre) engine output shaft to jackshaft measurement.

Every engine is different; some can have wildly different external dimensions which is why some people complain that they can't fit the left hand side chain without a half link, and others say they have too much slack in the chain; requiring spacer shims to bring the chain to reasonable limits of unloaded tension.

Another point needs to be brought into the equation: the Chinese (10 tooth) output shaft sprocket is frequently machined acentric, which is why the chain can be tight as a drum at one point in the sprocket revolution and looser than the front door of a lady of the night at another point in the sprocket revolution.
For this reason you need a left hand side chain tensioner because it significantly dampens chain vibration, not to mention that you don't have to worry about chain stretch and can let it run it's own course till it reaches 100% stretch.
 
Well I'm still trying to use the stock 415 chain with it. I have the chain tight and 1 thin and 3 thick washers and the chain has 1mm if even that of clearance from the jackshaft plate.
The sprockets don't quite line up with 3 thick washers (1 thin and 1 thick and it is perfect alignment) and I don't believe this is going to be enough clearance.
I don't know if I am trying to get this too perfect or if I am just SOL with all this.
I don't have any money left to buy a new engine sprocket let alone other stuff I should have got.
I know I need to use the thinner 410 chain that came with the shift kit for the engine output.
I saw other threads where they ground down there engine sprocket to fit a 410 chain. I have a dremel, I guess Ill go look up a tutorial for that.
 
Tried to remove sprocket to grind and now the cheap chinese gear puller tool is stripped! I cant get the gear off so now I guess I need to find a "real" gear puller. Jeezzuss!
 
Ladies and Gentlemen, please STOP! As the designer of the Shift Kit and one who has dealt with both Fabian and KC extensively some of what is being throw out here is opinion. There is no need to run a 410 chain on the left side. I have never run a 410 chain on the left side. I did fit one up once and noticed that some engine output sprockets will accept them and some won't. Please follow the instructions. Use the chain that came with your engine for the left side chain no matter what size it is. Our 17 tooth sprocket is designed to work adequately with both. Second if you are having issue with getting the correct chain tension let me help. Send me your engine, chains, sprockets etc and let me fit them. Once this is done I would encourage you to report back to this group exactly what I did to resolve your issue. I will even pay to ship it back if you get it here. Send me a PM or email me on our website if you are interested.
 
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