There might be no worse component to a motorized bicycle than the stock chain tensioner. It's so unanimously hated because it always has to be modified in some way to get it to function reliably, whether it be through the use of rubber padding, springs, brackets, etc. It doesn't even come close to working out of the box because you may only get a ride or two before it is loosened by the vibration of the engine.
Mralaska on motoredbikes.com came up with a simple yet elegant solution to this issue: throw it out and adjust the tension with motor mount shims! It makes perfect sense and leaves much less to go wrong. Honestly, I think the tensioner itself is far more dangerous than anything that could possibly happen without even having it.
I plan on trying this with my upcoming build because it just seems so right to me.
A warning to those looking to mod their motorized bicycles:
Most, if not all, of the hacks and mods featured on this site were made by individual hobbyists. If you are new to working with 2-stroke bicycle engines, please by aware that there's a possibility that a mod featured on this site could seriously damage your engine. Please don't try any mod from this or any other site unless you fully understand what you are doing. The owner of this blog will not be held responsible for both material and bodily damage caused by performing a modification featured on this blog. Also remember that opening up your engine may void your warranty!