Viper 99cc Head Bolt Torque specs

This forum is my last hope. I have scoured the local libraries, called the manufacture of the engine, looked at every web page I could find and cannot find any information. I have even gone to several small engine repair shops to see if they had any info. i am trying to replace the head gasket but I don't know what to torque the head bolts down to. some people have said to use inch ponds when torquing down the bolts. Now that I think of it, I will probably need the torque specs for rocker arms as well. listed below is all the information I have on the engine. 
 
Earthquake-VERSA compact tiller and cultivator
Model# 25780
Viper 99cc Engine 4-Cycle Engine
ARDISAM is the company who manufactures the earthquake tiller.

The Bolt head is 11.92 MM. The total length of the bolt from tip to tip is 63.14 MM long and the threads go up the shaft 24MM. The treads are M8-1.25. The bolts have a code stamped on them with the letter Z on top of the number 10.9.
 
 Z
10.9

Above specs are for a Yamaha 600cc engine
the head on this engine is a 4 cylinder, much larger than yours with 
a much higher torque value.   
 
.Hope this helps..
 
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