First remove the clutch cover to expose the clutch, bar studs and area of the tensioner.
Next you need to remove the bar studs. To do this tighten two nuts agains each other on the bar stud, then put a wrench on the lower nut and use it to loosen the whole stud. Repeat for the 2nd bar stud. Sometimes if you are lucky you can use vice grips on the shoulder of the stud to unscrew them, be careful not to damage the threads.
After removing the bar studs, the inner bar plate and tensioner assembly lift right out.
http://store.chainsawr.com/
My best recommendation is to take it to a certified shop, the tension screw base is located beneath many other adjustments dealing with timing. Tampering with other adjustments may leave your saw non-functional.
How many cc in a Stihl chainsaw
Stihl make their own chainsaws
The Stihl 064AVE was introduced on 1986.
The Stihl 064 is a 84.9cc chainsaw.
A Stihl MS 290 Farm Boss chainsaw costs around $370. This is Stihl's most popular model of chainsaw. It weighs about 17.4 pounds and has 3.8 Horse Power.
70cc
105cc
200.00
Stihl Hands Down
The Stihl ms210c sales for about $290!
STIHL 029 SUPER 56.5CC 3.8HP