Re: New engine trouble 66 cc.
Fully Agreed... Gotta crawl before you can walk, and gotta walk before you can run...
Concentrate on getting a bone stock engine running before even thinking about modding one of these... as simple as they are, they can still get messed up beyond help if modded with no experience.
Keep things Simple too... The engine only needs 3 things to run... Spark, Fuel, and compression. If it don't spark it can't run, easy enough... If there's too much or too little fuel it won't run... Keep it stock and it should still be easy enough. Main problem with fuel is contamination or something getting into the carb to block the main jet or to keep the float valve from shutting... Use a fuel filter to avoid this, and NEVER trust a brand new tank from China is clean on the inside, clean that thing out Good before assembling and installing.
compression... Same thing here... keep it stock until you know for sure what you're doing, make sure you got a good head gasket in there and torque it down to 80 to 120 in/lb,and Always torque in a criss cross pattern, not circular. the base gasket and the intake gasket also come into play here... as well as the crank seals, any of these leak and it won't run or it'll run very poorly. As long as you haven't removed the head or cylinder, these gaskets should still be sealing and intact, of anything has been removed, new gaskets are in order, Never try to reuse a base or intake gasket, the head gasket can be reused if it's perfectly flat and straight tho, but none of the others can, you remove a part that needs a gasket, replace the gasket before reassembling, that simple.
I prefer to spray my new gaskets as well as the head gasket with a light coat of copper gasket spray, this isn't mandatory, but it does help seal things up just a bit better, Indian Head gasket shellac also works very well but it's kinda messy and hard to get a nice thin coat on, not to mention it's a nightmare to remove and clean up if you have to remove a part with a paper gasket that was sealed with this stuff...
So.. Let's start with a new engine that has never been messed with or disassembled... get it installed in the bike as well as the carb and the fuel tank, line, and filter (you remembered to clean out the tank, right?) Now it's time to install the CDI unit... throw the CDI bolts in the nearest trash can, we're gonna mount the CDI with zip ties. Why do we throw the CDI bolts out and use zip ties? .. because 9 out of 10 newbs will tighten it too tight and crack the CDI unit rendering it useless, and 5 out of 10 experienced bike builders will do the same... we're gonna use zip ties here.
Now to wire the CDI to the engine we plug in the black wire to the black wire, the blue to the blue, and cut off the end of the white wire and tape over the end so it can't short on anything, then zip tie it out of the way. Tape over the black and blue wire connections too. If you're gonna use a kill switch to kill the engine, just make sure one wire goes to the black and the other to the blue, nuff said there, no way to wire this backward anyway, but after you got the wires connected, tape over the connections to prevent shorting out and to keep the install clean looking.
Now that the engine is bolted in and the fuel lines are set up and the wiring is done comes the fun part... trying to start one of these for the first time... it's not easy or fun but you gotta pedal and dump the clutch, edal and dump the clutch, and pedal some more and dump the clutch some more... It'll be tough to start that first time, and the next few times but it'll loosen up and become easy to start soon.
This brings us to what fuel mix to use, forget the instructions here, just mix up a batch of 24:1 or even 32:1 and go for it. 16:1 is really tough to start and just simply too much oil for the amount of fuel, which also reminds me... use 87 octane gas in your mix, the higher the octane, the harder it is to light off, and you're gonna have trouble starting it the first few times right? ... use the 87 octane gasoline.
Get it started and run it for about 10 to 15 minutes and sht it down until it fully cools down then repeat as many times as you wish, don't go too easy on it but don't stay at full throttle, or stay at any throttle position, keep changing your speed, accelerate up and slow down over and over again, load that engine up to seat the rings, but don't let it get too hot, shut it down after about 15 minutes for the first several rides to let it cool down.
after the first tank of fuel is gone you can run it longer but keep varying the speed, you will feel it start to get stronger and smoother somewhere during the second tank, this is also where it'll begin to start on the first try just about every time.
Hopefully I didn't forget to add anything in here and that covers it from assembly to break in, just follow these easy steps and it should be running great and easy to start in no time.