Carburator and other Questions

Throw the small spring in the trash or your spare parts box. It serves no useful purpose except to make the clutch harder to pull. Use the larger spring. It is indeed a heat shield.

Forget the 'boost bottle'. You'll simply waste your money. If you want more performance go with the expansion chamber but don't do anything until you have 200 to 300 miles on the engine. They are slow to break in (seat the rings) and adding performance enhancement parts will not help until it is fully broken in.

Installing a smaller rear sprocket will give you an increased top speed but will hinder low speed (take off from dead stop) performance.

Mix your fuel at 24:1 or better still 32:1 and ride the bike. After you've burned two or three gallons then start looking at performance parts but don't be taken in by marketing claims put out there by too many vendors of neck snapping performance parts. Also unless you are mechanically inclined and have some experience with small engines, particularily 2 strokes engines, ignore the advice to start doing modifications to the engine such as porting, piston trimming and balancing crankshafts. Leave the engine alone, at least until it is broken in and you have gained some experience.

Tom

Yeah, I don't know why they put that small spring in the kits. There is some theory that it helps keep wear off the clutch actuating parts, bucking bar and ball bearing. We say that if those parts are lubricated properly there will be little to know wear when the clutch is engaged.

Chain tension: Shoot for 1/2" to 3/4" slack. Measure it by leaving the clutch engaged and gently rolling the bike forward. When the piston comes up against compression the chain will go slack on the top run. Measure it at the center of the chain between the engine and rear wheel sprockets.

The carburetor with the handlebar control is the notorious CNS carb. Many don't like it because of the difficulty in tuning the beast. Those who have mastered it swear by it. And, it isn't actually a choke. It is a fuel enrichment control. A better option would be the NT carburetor. Simple, easily tuned and will provide all the performance you can expect from a stock, unmodified engine.
If you want a remote operated choke there are some old threads here showing what others have done using an old shifter lever, cable and a spring. Use the search feature and type in 'remote choke'. http://www.google.com/cse?cx=partne...19j12#gsc.tab=0&gsc.q=remote choke&gsc.page=1

You'll get lots of opinions on fuel to oil ratios. Most of us will suggest 24:1 for break in and 32:1 thereafter. Then you have weirdos like me who run 100:1 from break in on.
It is pretty much agreed that the kit recommendation of 16:1 is too much oil and will cause you problems like spark plug fouling and exhaust system plugging. Don't run more than 20:1 at the least. 32:1 is a good ball park ratio after break in.

Good luck

Tom

Congratulations. That first ride is always a thrill.

The stock air cleaner will perform just fine. There is little to be gained from a stock engine by changing it. Some of the aftermarket air cleaners 'look' better but offer little in the way of performance gains unless you have done some modifications to the engine.

As for performance enhancments, the expansion chamber exhaust systems will provide you with a noticable gain in power but wait until you have 200 to 300 miles on the engine before adding go-fast parts.

Many will tell you to replace all of the hardware (fasteners). In my opinion, based on my years of building and riding these motorized bicycles, it isn't necessary. Buy a good quality torque wrench and use it. I would suggest replacing the chrome acorn nuts on the cylinder head with shouldered hex nuts. It has been reported, and I've seen the acorn nuts bottom out on the stud before full contact with the head which can result in leaking head gaskets. Torque them to 120 to 140 inch pounds and recheck that torque value after a couple of heat/cool cycles.

Most of the problems encountered with the kit hardware is the result of overtightening. Also ignore the advice to "tighten all fasteners after every ride". I agree that you can 'check the tightness' but don't try to get a turn on the wrench or socket. If the torque wrench tells you it's tight, it's tight. Don't turn it anymore. That's where people break studs and cause fastener failure.

We always suggest to pedal up to about 10mph before releasing the clutch to start the engine then when slowing, disengage the clutch if you speed drops below 10mph. Adjust your idle speed so the engine idles just fast enough to keep it running with the clutch disengaged and make sure your clutch cable is adjusted properly so when you squeeze the handlebar lever the clutch is fully disengaged. You can test this by suspending the rear wheel off the floor and spinning the rear wheel with the handlebar clutch lever squeezed. It should spin free with just a little drag from the chain.
Hope some of this helps and answers your questions.
Good luck,have fun and ride safe.

Tom

Ditto: What Forest Rex said.
You'll also want to make sure there is no trash in the float valve. Even a tiny piece of crud can keep it open enough to flood the engine and cause overflow. If you have access to compressed air you might want to blow out the carb to clean it paying special attention to the fuel inlet on the carb.

Just to clarify and for your information, the engine doesn't actually "draw fuel" from the tank. It is strickly a gravity flow system. The fuel is drawn, or siphoned by the engine but only up from the float bowl through the main jet. Everything else is controlled by gravity.

Tom

I still don't know which carburetor you have. I hope it is the simple NT style and not a CNS. Whichever, they both have floats. Usually a round, donut shaped white plastic part that goes in the float bowl. It should 'float' in the fuel in the bowl. As the fuel level rises the float will rise and press against a fork shaped tang that will in turn press against the bottm of a needle valve that will shut off the fuel flow (or is supposed to). If there is a piece of trash stuck in the needle valve the valve can not close and fuel will continue to flow into the carburetor.
There have been many reports of finding the float full of fuel due to a crack or leak and the float will then not 'float' but sink and can't rise to shut off the fuel.

The carb should be close to level but it isn't necessary for it to be absolutely perfect. A little tilt in either direction won't cause the problem you have. Don't change your engine mounts.

Would it be possible to post a photo of the carburetor? That would help.

Tom

That is the NT and all the advice we've given so far applies to that carburetor. It really is a very simple device, easily tuned and very little maintenance. Just give it clean fuel and you should be good.
Have you checked that float yet, or the float needle valve? That's where I think your problem is.

Tom

Good for you. Before you install that new carburetor read this thread on sealing it to the intake manifold > http://motorbicycling.com/showthread.php?t=52865
There is some good information/discussion there.

Good luck, have fun and ride safe.

tom