Help! I can't get my motorized bicycle to work :(

[RyserGuyser]

For starters, I should let readers know that I am not very familiar with engine terminology, so please be descriptive!

Here's the lowdown: I ride the bike to pedal start, get up to a good speed and release the clutch. The engine turns over, and makes the typical engine sound (it is definitely burning gasoline) but the engine provides no power output. As soon as I release the clutch and engage the engine, it just bogs down and rumbles very low. If I give it gas via the throttle, revs a tiny bit higher, but still very bogged down. Many many times I have tampered with the choke, the screw that adjusts the min throttle, and the little pump that put gasoline into the engine.. all to no avail.

Here's my troubleshooting history: The gasoline/oil mix is correct and works fine in my friend's bike.. it's not the issue. Also, I have completely disassembled and reassembled the carburetor (according to YouTube videos) and it is functioning correctly. Furthermore, I have also tested the spark plug but putting it in a friend's bike and it is working fine. Finally, I tested the functionality of the kill switch and checked the resistance between all 3 wires coming out of the engine, the ground, and through the coil. Everything is wired correctly and thoroughly insulated.

This has led me to believe that the issue is with my actual motor, something I know very very little about and I feel least comfortable tampering with.

Does anybody have any ideas as to what the issue is and what suggestions do you have for fixing it!?!? Any links to how-to YouTube videos would be great too.

Thank you so much!!
Ryan

 

[Saddletramp1200]

If the head, where the spark plug is, is loose you won't have enough compression for it to run. Also take the plug out and plug it into the cap and have someone hold the rear tire off the ground. Peddle it. The plug must be on the engine to check for fire to the plug.

 

[Mozenrath]

If you haven't done this already, open up the bottom of your carburetor(the thing that's attached to the engine intake neck) and see if the jet is loose or unscrewed. I was having problems getting my engine to run recently, and it turned out that it unscrewed from engine vibration. Some of these carburetors even come from the factory without having the jet screwed in. Screw it in nice and tight, put the carburetor back together, and try starting the engine again.

http://www.youtube.com/watch?v=dPGx9Um6DP8

Skip to 5:25 in that video and watch how the guy opens the carburetor and screws in the jet. It's pretty easy.