6-Speed kit
This is all you need to carry.
An excellent X-country motorcycle like the XR400 would be even better with 6 speeds (a lower first and a higher 6th). Here's a simple way to pretend your 5-speed is a 6-speed (as close as you'll get). This method will work with other motorcycles too, we'll add them if folks write in with "the answers".
If you have a long hiway section in your planned route, start with the 15 tooth countershaft sprocket. When you get to the trail, changing to a 13T takes only a few minutes. Even less time if you're properly set up. Substitute the stock fasteners for the cover and the sprocket retainer with socket head cap screws, all of which can be removed with a single hex wrench.
You should be carrying an (1) axle wrench anyway (as shown, 17mm welded to 15/16=24mm; XR size). With the method shown below, all you need to carry (additionally) is (2) one 5mm hex wrench and (3) one countershaft sprocket.
Simply switch the sprocket and readjust the chain. The axle moves 1/2 (=8mm) of the pitch forward for the 15T or 8mm rearward for the 13T.
Stock gearing for the XR400 is 15:45 (which equals 14:42). If you change to a 42T in the rear, then the 15T "gears up" 7% (from stock) and the 13T "gears down" 7% (from stock).. A good chain length for 13:42 and 15:42 (is 106 pins). It's a common question as to how to copuunt the links, do you include the masterlink? The answer is "count the pins" in the completed chain" that is the correct number.
Further notes: I'm now using 13/15 -to- 43. 106 pins is perfect, it allows plenty of room for chain stretch. I tried a 16T (Renthal p/n 279-520-16) with 43T, for this you need 108 pins.
