Re: Please Help
Hello V, and welcome to the forum.
First off, the fuel mix thing... If you use the Google site search above (sandwiched between a pair of banner ads near the top of the screen) you'll find a wide variety of opinions on what ratio to mix to. After break in, I run mine at around 40:1, or 25ml oil per liter. But that's me. the ratio can run up to 100:1 depending on the product you use.
Now, when you say the muffler falls off, do you mean it comes undone from the side of the engine and the whole works comes off, or is it the end cap that keeps going? (I've played find the end-cap a few times, but never had the whole unit drop off..) Does the bike have the holder/support for the muffler, or is it simply hanging off the studs on the side of the motor? Back pressure provided by the exhaust is essential to a 2-stroke's operation, so if the whole muffler is disconnected running that way can lead to damage to the engine.
As for 'sputtering'.. not quite sure here.. On the bikes I've built the 'sweet spot' in the throttle has been a little different for each, and the motor will sputter and 4-stroke a little just under or over that zone, but once you find it you'll know it. The motor will smooth out and start a nice smooth power climb/ramp-up without having to move your hand/change throttle position until it levels out and is ready for a bit more gas. It's difficult to explain, but you'll know it when it happens.
Hope that helps a little.
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