Changing the rear sprocket is one of the easiest modifications showing the greatest noticeable change of any modification in the ride-ability of any chain driven VT750 motorcycle including the Shadow Spirit VT750DC, the Shadow Ace VT750CD/C3, and the newer VT750RS. Due to clearance issues the front sprocket must stay at 17 teeth and cannot be changed to a larger tooth sprocket for any added benefit on any modern VT750 motorcycle.
The stock higher tooth count sprocket used in the older Shadow 750 models makes for quite zippy acceleration but leaves the engine sounding like it is over worked at 55mph. From the factory the ACE came with a 41T sprocket, the Spirit a 42T from 00/01 - 03 and a 41T from 05-07. Thankfully Honda avoided using a high tooth sprocket on the Shadow RS line as it comes with a 38T from the factory. Imagine being able to simply cruise along at 70mph without the engine screaming at a ridiculously high RPM or whishing you had a 6th gear. On older Shadows the way to achieve this comfortable cruise-ability is to simply change the rear sprocket to fewer teeth for a more desired gear ratio. Perhaps you want a more zippy ride on your VT750RS you could step up to a 39 or larger tooth sprocket for a peppier take off.
Although a fewer tooth sprocket will take away some zip off of the line it is well worth it if you do a lot of higher speed riding. It is recommended that if you go below 39 teeth, you should change your clutch springs to stiffer after market ones for better grip (changing the clutch springs is the perfect time to advance the timing with the 4* timing mod, instructions by Blacktop).
Instead of recreating the wheel, more info and instructions on changing your rear sprocket can be found at Fishman's VT750DC.
By far the most common Sprocket sizes are the 38T and 39T for the chain driven ACE and Spirit for better highway riding. The stock chain length is 122 links. For the 38T a 120 link chain works perfect. A 39T sprocket can either a 120 or the stock 122 link chain although the 122 will have to be tightened quite a bit from the start. Note that the JT Sprockets model 1372 (front) and 1304 (rear) fits all of the VT750 chain driven models including the ACE, Spirit, RS.
17T Front , 38T Rear, 39T Rear, 122 Link Black Chain, 120 Link Black Chain
(Front Sprocket/Rear Sprocket = Gear Ratio)
17/36 = 2.12
17/37 = 2.18 (PMP Sprockets in TX sells 37T sprockets that fit the VT750)
17/38 = 2.24 (most common and easily found aftermarket sprocket)
17/39 = 2.29
17/40 = 2.35
17/41 = 2.41
17/42 = 2.47 (stock gear ratio of VT750DC)
17/43 = 2.53
17/44 = 2.59
17/45 = 2.65
17/46 = 2.76
525 O Ring or X Ring chain - 120-122 link length needed for 38T or smaller sprockets, (122-124 is the stock length).
If your chain is still in good shape you can shorten it after a sprocket change and keep using it. You will need to purchase a clip type masterlink and then remove two outter links from the chain so you can remove one internal link to actually shorten the chain. Your shortened chain shoudl have two internal links exposed at either end so you can attach the clip type masterlink (note always install the clip with closed end facing towards chain direction or it could fall off causing serious injury or worse).
To remove the outter links from the stock chain you simply pick a link and then use a chain breaker (if you have one) or a dremel tool / angle grinder to grind down the two rivets / link pins on one side flat and flush with the outter plate. Once that is done a large flat head screw driver can be wedged behind the outtler link of the chain and used to pry it off, after that link is removed the other side of the outter link can be removed including the attached pins. You need to do this to remove two outter links and one inner link in order to shorten the chain. Below on the left, the parts that need to be removed are circled in red. The right shows what the two ends of the chain should look like to accomodate the new masterlink.
Aluminum Rear Sprocket: 815-## Tooth Count:(37-66)
Steel Rear Sprocket: 815S-## Tooth Count:(37-40)
Steel Front Sprocket: 599-## Tooth Count:(16-17)
Steel Rear Sprocket: JTR1304-## (38-47)
Steel Front Sprocket: JTF1372-17
Note: This information applies to ALL chain driven VT750 models.