Re: reliability question ( 2 stroke HT)
Luck of the draw when getting the China girl engine plays a part in the whole mix of things, but several other things have to be factored in if you hope to get reasonable reliability from even a good engine to start with.
Remember in many thing less can be more, what I mean by that is dont think that a whole pile of neat gadgets automatically translates into all things being better and more reliable, we have vendors here and elsewhere who do have quality upgrades that actually add to better looks and better reliability potential, but on the other side of the coin we have the snake oil stuff also.
I say, before you even put a wrench on the engine, potential good reliability starts with the bicycle itself, personally I dont think you need a high end high dollar bike, but if you can get higher quality frame, that isn't a bad thing atall and is a plus no doubt.
I have found that most all regular bike wheels can be very reliable and have a long life.
1. true the wheel and make sure spokes are all tensioned good
2. use a HIGH quality tacky grease in the front bearings and the rear hub whether it is a multi-speed wheel or a coaster hub. an easy to find and very good grease in my opinion is Lucas High Tack Red Grease, AutoZone and other auto parts store normally carry it.
3. make sure that bearing tension on wheels is as tight as possible without binding, and check for loose bearings in wheels before every ride by shaking wheel side to side and watching for bearing slack, I have several 1000 miles on my bikes, all have standard quality wheels and no issues with any of them having ever had a bearing failure.
I do recommend if you want to run a coaster brake rear wheel, try to get one with a Shimano Hub, they are better than the other china made hubs, better bearings and better braking for sure, but even with them I take them apart and re pack with quality grease.
As for the engine;
A quality upper wrist pin bearing is essential, good quality intake gasket, a well tuned carb, ( prefer the RT and the NT Speed carb myself, either will do a great job.) ,quality spark plug boot (NGK or and automotive boot) ,a better free flowing exhaust like a SBP expansion exhaust is a great way to go if you will replace that short life silicone hose with copper pipe fitting and use a spring and hose clamps to hold joints together, if you run a chain tensioner roller, use one that is better than the kit roller, I have some made up that I have sold a few of that have high quality bearings and the rollers are bullet proof, I make them out of skate board wheels and they work great.
use a quality KMC 415 or even better 415H chain and if you run a rag joint sprocket adapter make sure it is mounted corectly to wheel, straight and true and use a dab of thread locker on mounting bolts, for an even better look and better long term reliability, the Manic/Pirate/Jakes/....etc clamshell sprocket hub adapters are the best looking set up and are less wear and tare on the wheel spokes for sure.
There are a few other little odds and ends to be considered of course, but in my experience the things I listed here are a good start for having a China Girl Build that will give pritty good reliable service.
Two more things that are important, if you try to blow it up by running it WOT all the time, you will....!
If you don't run a quality oil at the correct mix, you'll have a short lived engine.
I'm sure others will chime in and add to my opinions here which is great, I have not had a problem with building fairly reliable china Girls once I knew what the important things are to do first off and the things to keep an eye on regularly.
Best wishes on the Hobby build, but for the main everyday ride the Tomos will get you there and back more reliably I'm sure.
I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!