On the contrary, you need to use a torque wrench. It would be too easy to strip the threads otherwise as the specs are: NE head bolts 168 to 175 inch pounds for the 8 MM bolts and 210 inch pounds for the 10 MM bolts. Always torque the bolts when cold, never when hot. Since you're working with aluminum, start at a lower number and work your way up.
I am back! Sorry I haven't had time to help out on the site, but have been very busy with a lot of legal issues over the last week.
If you try to tighten the head bolts without using a torque wrench, it is very possible to pull the threads out of the cylinder [more so on the 2007 & 2008 models], and sadly the most important bolts to check are the center rear and left rear [nearest the exhaust]. I would suggest removing the tank, removing the rear belt from the sheeve, remove the front clamp holding the bar to the frame, loosen the top rear mount. At that point you should be able to "push" the motor to one side and be able to torque the rear bolts. I know this is a lot of trouble, but it is common [although others might tell you differently]for the rear head bolts to work loose and cause the head gasket to blow [I have over 50 blown head gasket hanging on a nail in my shop].
I may have come up with a solution to this problem. I made two extension attachments, 6 and 8 MM, by drilling a hole through a socket crossways, inserting a hex key in the hole and welding in place. The socket is mounted on the torque wrench and it is possible to reach all the bolts with this setup. Adding lenght to the wrench changes the torque value on the bolt. There is a formula to compensate for the extension. An extention (adding overall lenght, not a regular socket extension) CAN NOT be used on a torque wrench that dose not have a pivoted floating handle, such as most dial and clicker types. There is no way of knowing the exact point where the force from your hand is applied to the handle. Without such a point it is mathmaticly imposible to calculate the torque at the end of the extension. Another solution may be to make a C shaped attachment to go up and over the gas tank. As long as the drive square on the wrench is in line with the hex key turning the bolt the torque value will be the same.
I figured out how to do this. Please read my above post and piece the procedure together for yourself. The head gasket on my Whizzer was leaking. I needed to torque the head but there was no room for the torque wrench. I did not want to remove the engine. First I made an extention that would reach the bolts. Then I made a crude torque indicator as follows. I welded a long (about 18") pointed rod to the head of a 1/2" bolt so it would sweep like the hand on a clock as the bolt turned. I screwed that into a nut that was held tight in a vise. Next I set my clicker type wrench for 210 IN LBS, the torque I needed on the head bolts. I made a hook that fit the wrench handle so I could pull from the exact same point every time. I applied torque to the indicator until the wrench clicked, 210 IN LBS, then I set a mark at the end of the point. I tried this a few times to see that the point returned to the mark every time. The indicator was loosened before each test. Next after reducing the setting on the wrench, the extention was used to torque the indicator. Through trial and error I adjusted the wrench until once again the pointer met the mark. The setting turned out to be 175 IN LBS. I did the same for the 180 IN LBS bolts also. I found that changing the torque setting by 5 IN LBS would change the stopping point of the indicator by about 1/32". I figured this should be close enough and, with the head bolts slightly loose, I tried it out on my bike. No more leaking head gasket! I dont think this method would be acceptable for NASA parts but It was a great learning experence and it worked for me. This may save you guys that work on these a lot of time. Danny