Hi. I've joined the forum after a few weeks of stealing tips and tricks while building my daughters moondog for her birthday. It was a learning experience to say the least, but the bike runs great and my daughter loves it. Some things I learned. - The stock chain tensioner sucks. I fabricated my own spring loaded one using some tips about the nice rubberized roller from the Tractor Supply mentioned on this thread. Part Numbers. #165-063 Chain Tensioner with roller. #165-280 Chain Tensioner Spring. - The stock chain sucks. Stretches badly, and likes to jump off the sprocket. Switched it with a #41 from the Tractor Supply. - The chain tears up the rear tire on the MoonDogs, because they are so fat. Bought some 26" mountain bike tires from Target for 9 bucks, and they work great. Skinny enough to keep the chain from digging in. - Pull off the fenders on the moondog. The make too much noise, and are more aggravation than they are worth. Fabricate a *small* fender out of the remains to keep the mud from wet roads off your back. - Locktite *every* nut and bolt. If you don't, you'll soon find your engine coming off the bike, your exhaust coming off the bike, and your sprocket moving about freely. Very bad.. - The stock exhaust gasket is terrible, and will leak and turn into sawdust quickly causing a loss of pressure, and oil leak that makes you think your case is cracked. Make a pattern for new gaskets out of beer cans, and cut them (make sure you dont cover the exhaust port). Stick two of them on and tighten the exhaust. Works great, and bike is now very quiet. - Your kill switch wire cannot cross your el' cheapo Bell bike computer, or it will continue to reset the computer everytime you turn the engine over. You also want to stick a small piece of rubber in the battery compartment to secure the battery and keep it from randomly cutting off the unit from the vibrations. Also, mounting it to the handlebars with a few layers of cutup tire tube under it will prevent odd behavior from vibration as well. - If you are going to do a front 'drill through' mount on the MoonDog, make sure you get some oversized washers and bend them around (form them to)the downtube, then use one on each side of the downtube. This create a much nicer grip on the downtube, and prevents the engine from moving to the side. In hidsight, next time, I'd probably fabricate an extended mount so I can put bolts on both sides of the down tube, instead of through the center of it. The center mount creates too much of an awkward pivot point. - Tighten your spark plug (your new one..since the stock one sucks), tightly (but not so tight you strip the threads...its an aluminum case so be careful). If you don't find that 'happy spot', you will see oil leaking out of your spark plug. - Use a zip tie for the rear of your chain guard. Makes the guard quiet. The stock mount that comes with the engine doesn't work too well. - Use cut up inner tubes between your bike's down tubes, and engine mounts liberally whenever possible. It makes a nice strong mount, and prevents scratched paint. - The screw on the clutch lever likes to work its way out. I pulled it out, and used the screw from the chainguard mount. It's longer, and works much better. - If you ever want to get into the business of building and selling these bikes it wouldn't be hard. I drove the bike through my neighborhood, and had 3 people ask me to make them one. Apparently people like the 120 mpg thing. - Use an inline fuel filter. It not only keeps your fuel clean so you don't clog your carb with all the junk in the stock gas tank, but it for some reason uses *much* less fuel when you have it in. - Make sure you turn your fuel selector switch to 'off' while the bike is at rest. - If your going to let your kids ride a motorized bike, make sure they wear helmets, long pants and gloves.