Don't let my wife become a widow. Help now!

I just finished installing the new engine. It runs and idles fine. My problem is getting it started without dropping from exhaustion. I watch YouTube videos where someone starts his bike by just peddling a few feet and popping the clutch. That’s discouraging enough, but then watching the video where the guy picks up the bike’s back end and kicks the engine once to start it makes me want to pitch mine off a cliff. Despite my incredibly good looks and youthful appearance, I no longer have the legs or cardiovascular system of an Olympic track star. I’m therefore hoping somebody out there can help me before my wife becomes a widow.
So here’s the problem; to get the engine started takes an awful lot of peddling. Sometimes even peddling combined with a long hill. It doesn’t seem to make too much of a difference if the engine is cold or hot. To start it initially I’ll turn the gas on, close the choke, give the primer button a push or two (although I can’t say this ever makes much of a difference), and start peddling. The plug is a brand new NGK (can’t remember the model, but it’s one that’s recommended). Eventually it’ll catch and you’re off. Keep it running and you’re fine but, turn it off and you’d better hope you’re not at the bottom of a valley.
As far as I can tell everything is fine, no vacuum leaks, good CDI, proper new fuel mixture, etc. What could be making it so hard to start? Could it have to do with fuel mixture? I’ve been thinking maybe it’s the carb mixture needle setting. Its clip is on the center slot of three, just as supplied. If I move the needle’s clip to the lower slot would that richen the mixture, and is there a reason I shouldn’t do this? The engine smokes, but considering the fuel mixture I’m surprised it doesn’t smoke more. Should I try moving the clip to the top slot and try a leaner (right?) mixture, or will I just burn the thing up?
I’m not sure whether it makes any difference with these engines but, I’m not at sea level. The engine would see an elevation between about 1,000 ft. and maybe 1,500 ft. The air at this time of year is dry and cold. It’s been about 40 deg. F during the day.
My plan is to ride the bike to work this summer but, I’m not sure how long I could hold out. If someone out there in moto-bike land has a brilliant mind, now’s the time to prove it. If you can help me I’d be eternally grateful!
Many thanks,
Geo in vt.

First I'll answer some of the questions you guys asked, and then I'll tell you about what I found and ask for your opinions.
• Engine: 66cc China girl. Prior to installation I removed every piece of threaded hardware and replaced it with real stuff. Nuts and bolt are either grade 5, 8, or stainless, depending. Where possible socket head cap screws were used instead of slotted or Philips. Head bolts were all evenly torqued and everything was Loctite’d.
• Bike: 6-speed mountain bike with shift kit already installed but temporarily disconnected. Right now I’m running on just the sprocket that came with the engine.
• Runs well on level ground. There are no issues with compression. I haven’t put a gauge on it yet but it’s not easy to turn over without being rolling. Remove the plug and you can crank it by hand.
• Carb: stock NT
• Fuel mixture: Yes, I am using the suggested 16:1 mixture.
• Spark plug: iridium
• Gap: I set it to 0.024”
• Plug wire: the one that came with the bike.
• Wired: I’m not using the white wire. The other connections are made through a waterproof military grade, plug with gold plated connectors. I have no worries here.
• Idle: Yes, it idles nicely. I haven’t put a tack on it yet but I’ll guess it’s idling around 4 – 500 rpm.
• Exhaust: The stock exhaust was used however, I extended it about 18” using ½ copper pipe with a small lawn tractor muffler at the end. I don’t think this had any measurable effect on back pressure. By the way, while building the bike I was worried about how noisy it was going to be (lots of You Tubes where people complain about noise). So, in addition to adding the small muffler extension I also carefully and tightly wrapped the entire exhaust in high quality muffler wrap. Lastly I sprung for the extra liners that you can put behind the different engine covers. This bike is really quiet. Amazingly quiet. I can easily have a discussion with someone right next to the bike, rev the engine and speak in a normal tone.
So now here’s what I’ve done prior to getting your suggestions. Thinking that maybe, because of my 1000 ft. elevation and cold dry air, I was running lean I moved the clip on the carb’s fuel mixture needle from the center position to the bottom. This made a huge change in starting the bike. Huge. By initially fully choking, then slowly dropping the choke to fully open, the bike starts and runs like I first wanted it to. The only issue I have, which I’m hoping to get your opinion on, concerns the idle. Starting, and keeping it running, was a ***** before making the needle change but, it did idle better than it does now. I wouldn’t say it’s bad now, but I wish it were a bit smoother. It’s idling at about the same speed as before but, it skips or misses a bit. Also, when riding at low speed, it “chugs” or “lurches” and, unless I keep on the throttle. I’m guessing it’s a matter of not having a low speed mixture adjustment. In other words the mixture needle change allowed more fuel for easier starting, but too much for running and idling. And, if someone’s willing to give me a little more info:
• What do you think about the iridium plugs and should the gap still be 0.024”?
• What’s wrong with the 16:1 fuel mixture?
• From what I’ve read the white wire is a 6V power source for say something like a headlight. Should I use it? Anyone know of a light this will work with?

Many thanks in advance everybody!

KC - I checked out your website and was amazed at the number and variety of bikes you've got. I have a question though. It looks like you use a CDI which has a key lock. Do you sell these?
George

Never mind KC, I found the ignition switch on your website afterall. But, your website also led me to another question. Some of your bikes use a small rear mounted cylindrical tank. You have one tank rack mounted and another mounted on the seat post. Are these tanks available through you? Thanks again, George

She's running like a top! I switched to 32:1 mixture, cleaned the plug, and the bike runs great. Since it now starts and runs reliably I was able to switch from the direct drive back to the jack shaft. Its still a little difficult to get it started without the help of the rear wheel, but certainly possible.

Despite a cold rainy weekend here in northern VT, I couldn't resist getting it out on the road. It worked beautifully until BLAMMO - NO MORE CLUTCH. What happened is that the little screw holding the clutch adjustment nut in place vibrated its way out. This allowed the adjustment nut to thread off. The screw ended up being pushed through the cover as the nut came loose. New parts are now on order and she'll be back in operation soon.

I replaced and Loctite'd every single nut, bolt, and stud on the engine, except for this one. This one never occurred to me. My plan for the repair is to replace the screw with one that's drilled for a safety wire. I'll then drill and tap for a second screw close to the first. The two will then be safety wired together. This will lock the two screws in place and prevent another disaster. There's not a lot of clearance under the cover but it can be done with care.

Thanks to everyone for your help in getting the bike up an running.