On these units having the chain too tight is much worse than having the chain a bit loose. Also, since on most of these units the sprockets are not perfectly aligned on the shafts you need to rotate the sprocket 90-degrees, check the tension, rotate 90-degrees, check, and repeat until you've checked an entire rotation of the large sprocket. You then want to adjust your chain so it has the proper slack at the tightest portion of the sprocket.
Also be aware that the chain tension has a habit of changing when you tighten the four bolts on the left sprocket housing. It can be very frustrating sometimes as you can't really predict if the chain will loosen or tighten with the bolts. You just have to keep playing with it until you have the proper chain tension when the bolts are all tightened.
