Shift kit questions

[ninjaplatypus42]

I'm going to build a new bike with a shift kit from sickbikeparts and a 60/80cc 2 stroke. I just have some questions about it.

1. Has anyone had issues with the 3/32 bicycle chain breaking?
2. What speeds have you gotten in top and bottom gear (also how many teeth are your bikes top and bottom)
3. What is a reliable speedometer that can handle the higher speeds (preferably not a 75 dollar computer)
4. Are tensioners on either side necessary? I've seen mixed opinions.
5. Exactly how much space does the engine with the shift kit take up? My bike is a little smaller than I'd like and it's going to be close I think.

Thanks for any insight you have!

 

[vatoed]

I have not had issues with the chain breaking except for once when my chain came off the front sprocket and it bound up pretty bad. I had a crooked rear hub that has now taken care of my wobbly chain situation and I also bought a chain guide for the front sprocket off of Amazon and it is working nice to keep the chain on the sprocket.
My Skyhawk is running really nice, I've got it jetted exactly the way I like. I'm using a banana pipe and stock carb. I get a good solid 36-37 mph on level ground. I have gotten peaks of 40mph. I weigh 235lbs.
I am using a CatEye speedometer also from Amazon. It was like 16 bucks. I bought the wired version because the first one I tried (not a CatEye) did not work, I assume because of interference with the ignition system. The wired one I have on now works flawlessly.
I just added tensioners to my bike, I don't think they are absolutely necessary but they do help keep the slack tight on the chains. I feel less of a jerk when coming back on power after a shift or slowing down. I'm also just looking for crap to buy for my projects.
my bike frame isn't too big and it fit well. I would liked to have room for a front engine mount to gain some room between the front tube and the engine because I could not find any muffler that fit with the engine strapped directly to the front tube, and this happened on 2 shift builds that I have worked on.

Over all this is my best, most confortable and enjoyable bike. I love having the different gear options and a lot of times I just leave it in one gear and use it just like when I had my single gear bike except for now you get to choose the ratio you want to be at depending on your terrain. In my low gear ( I have a 34-14 megarange sprocket <- also available on Amazon) I can climb some pretty steep freakin hills that would not be possible by pedal power.
I believe that once you go shift kit you will never go back. Just do yourself a favor and get very familiar with your rear derailleur and adjusting it. I learned how to on youtube and have been able to lock it in perfectly.