It doesn't matter if you lack mechanical skills. You can do it! This is the perfect product to learn some basic mechanical skills. Just be patient and ask a lot of questons that will help you to resolve one problem at a time.
Just remember: When finished you will have created a motor vehicle capable of enough speed to cause injury. If anything looks a little unsafe it probably is! Once you finish have a mechanic look it over.
The first one I did was brought in by a customer who couldn't get it to work. Fortunately he had totally cobbled up the throttle, (It wouldn't turn), otherwise he would have had a hot motor with a chain wrapped around his ankle!
Most of these kits lack instructions.
I'm sure you will be ale to find somebody in your area that has done one of these installations. If not, maybe you can fnd an auto mechanic or motorcycle mechanic that would be willing to help, especially being that this is a unique thing.
Once you get it going it will require constant maintenance. You will have to learn to enjoy working on it.
The clinking sound? shouldn't be from the cylinder head unless:
The head is not tight...combustion escaping can sound like what you describe.
The piston is hitting the head...unlikely
The head gasket is missing, or damaged...same effect as loose head bolts.
In trying to resolve this problem post anything new that you discover. It will be the best way to get comprehensive help from other members.
Then we can tackle the next issue, and so on, until you're up and running.
These bikes are fun, and well worth the effort.