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To add to the mix, I'm now also producing a Chromoly 4140 Hardened Rockwell 36C front sprocket for the stock 520 chain. These sprockets are hard clear through, not case hardened as most front sprockets are. This means it'll last a LOT longer. Going up to a 16T front is basically about the same as dropping 3 teeth from the rear. With the stock 15/45 gear ratio you have a 3.00 ratio. With a 16T front, this takes you to a 2.813 gear ratio, and still uses the stock 112 link chain. You can see the gear ratios and chain lengths for various sprocket gear ratio configurations here:
https://docs.google.com/spreadsheets/d/1T42Kjs53Xbad4d_krrIw5OPAEve9NntuLEwNRPkrnOY

520-16.jpg

These sprockets are made by yours truly on the Formula390 Vertical Machining Center. That means that they are made here in the USA, with 4140 Chromoly Steel which is also produced here in the USA.
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Formula390 Sprockets Page
 
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antarius

New Member
Beautiful.

Any idea how much further in we gotta move the rear wheel to keep proper chain slack? 1mm? 2mm? 5mm? Just curious for my notes / geometry before I go with one. I definitely need to adjust gearing for one of the tracks I ride at - hitting the limiter about 1/2 down the front straight, LOL.
 
D

Deleted member 452

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It's a bitch to get the chain on with this combo. You'll have to move the wheel all the way forward and put the chain onto the front sprocket before placing the sprocket onto the output shaft (It's that tight of a fit). Once on, you'll end up moving the rear wheel backwards a little to take up the slack and then you're golden.

I also tried adding 2 links the last time I replaced my chain but then the chain was too long so I kept the link # the same as OEM. On the street, a 16T sprocket is great since 1st gear is so short and cruising at 70mph is much more relaxed.
 

Formula390

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Beautiful.

Any idea how much further in we gotta move the rear wheel to keep proper chain slack? 1mm? 2mm? 5mm? Just curious for my notes / geometry before I go with one. I definitely need to adjust gearing for one of the tracks I ride at - hitting the limiter about 1/2 down the front straight, LOL.

As bahawton stated, the fit is a little tight. It's certainly MUCH easier if you break the chain and use a new masterlink to fit everything. That way you can thread the chain over the sprocket and back under the swingarm. Then push the wheel all the way forward with the adjusters flipped to the shorter side, and you can still get a 112 link chain on there. 114 links is, as bahawton also said, too long. 112 links is the correct chain length for a 16 Front and a 45 Rear setup.

I have the sprocket combination ratios and chain lengths / link count all calculated up for everyone here: https://docs.google.com/spreadsheets/d/1T42Kjs53Xbad4d_krrIw5OPAEve9NntuLEwNRPkrnOY/

That speadsheet shows all the ratios, so you can use that as a guide for how much of a change of ratio you'll have with the various sprocket combinations.

If you are hitting the limiter 1/2 way down the front straight tho, yes you certainly need to gear for more top speed. I typically try to aim to hit readline somewhere around my latest available braking point (where I can hopefully still make the turn) at the end of the longest straight. If you are geared for more speed than that, you are just leaving power on the table... and if you are geared for less... then you're bouncing off the limiter and reaching for a non-existent 7th gear. :)
 
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