Frankly? Drop your float bowl every 3 months and check for boogers and green schmutz, get a MAPP torch and burn the carbon off your sparkplugs every 2000~3000miles.
Oil your chains and adjust the tension, make sure you store your bike(s) and gasoline in a dry place. Wipe bike down after a few trips. Don't forget to tune your brakes and put a drop of oil at the start of any critical control cable. Clean your brake pads and rims/disc with rubbing/stove alcohol, clean dry brakes are safe brakes, especially when they're working in the proximity of a smoke belching engine.
For real reliability, (and I run a 48 cc cheapy Amazon bought engine..) was to change out the NT carb for a Yamaha PW50 clone carb.
It required an 18 gauge aluminum shim to fit the intake spigot. I also replaced the stock O-ring on the manifold clamp with a Viton one from Autozone. It will also need a thumb shifter, cable and sheath to work the enrichment valve. Usually the Yamaha carb kit comes with the cables to replace the stock ones, so you have options on how you control the enrichment valve. I've owned a lot of Japaese motorcycles with enrichment valves. They're an established and reliable choking device that is more modern and can progressively enrich the mixture so you can turn down the level of enrichment as the engine warms up. They work better than a choke, IMO.
Having an enrichment valve is also an boon if you find your main jet gets a bit of debris and starts to lean out, you can dail in a moderate amount of enrichment to bring the engine power back. It does make idling dicey. The enrichment is also very direct. I can 'kick start' the bike using first gear while holding the rear tire off he ground. It always starts immediately.
What I gained from the conversion is this: The float is one piece plastic, ( with no bendable tangs like the NanTung...) with a real, spring loaded Viton tipped needle working in a precision replaceable seat so there's no float bowl level drift. A real idle fuel mixture circuit with a mixture control needle, the needle controls the air part, so screwing it in richens the idle mixture. I find that my little 48 cc is pretty sensitive to this, so having it a little on the rich side means it transitions OK when engaging the clutch after starting off under pedal. An enrichment poppet valve, cable controlled to the handlebar so I'm not having to futz with the choke between my legs while pedal starting the engine. The main jet is brass and can be soldered and redrilled to lean it out and replaceable with jets made for the VM series of clone carbs. Parts are not a problem. The carb is cheap, $19 to $30 and it's decently made.
Well it's that time again...lol...My bike, with the Zeda 80 motor, seemed a little sluggish to me on my way to church Sunday morning so i decided to do some maintenance on Tuesday, (Yesterday). First, I took the gas tank off, cleaned it all out, installed new petcock with in tank fuel filter...
Hey so I'm thinking do you replace working parts with new parts at mileage / time or when they break? For me I found myself doing a full overhaul on my 66cc cg around 1000 miles or 1.5 years it worked out to be. Reason clutch or bearing failure . still ran but clutch was stuck on with grinding sound. I was on original 415 chain and idler pulley, carb, bottom end, exhaust, and clutch. cdi I replaced just because at 750 miles but ran the ngk plug all the way to 1000 miles... top end 2 or 3 times because of c clip ear failure every 250 miles.
On this new cdh pk80 build, I did all the reliable upgrades. ngk plug, magnetic fuel filter, #41 chain, new idler, lock tight, HP head, open port jug, cw10 c clips for piston, but still reused some now 1000+ mile old parts, such as carb, exhaust, throttle cable, kill switch... as of now with 218 miles it will rip to 32+ mph but i cruise around 24-27 easy with great mid range power for hills.
If you grease the bearings, they live longer. All I do is grease the bearings every month or few hundred miles and clean my chain and regrease every so often or after a dirty or wet ride. An grease the drive gears. Now and then I will clean the clutch pucks, but other than normal bike maint. It's all I do. Maybe ever few years toss a new plug in, but I use marine grade plugs and well they don't really need changed. They probably will last the life of the engine, and at 5k plus on one of my engines, well it's not showing any sings of going down soon.