49cc trouble

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Youngster8

New Member
Feb 9, 2011
5
0
0
NY
Let me start by saying hello to everyone. This is my first time posting and I really enjoy looking around the site. So, I am inspired by everyone here and I am planning on building a bike. First thing I have to do is get the 49cc engine on my scooter working because that is what I plan to use on my bike. I am far from an expert when it comes to engines but I know the basics..I think. So here is where I am stuck. The scooter has an electric start on it. When pressed all the engine does is keep on turning over (i think that is the lingo) and over again and again without starting up. When I press it and give it gas it bogs down and dies fast. I checked the spark plug and it is wet so I know it is getting gas perhaps too much. The thing is I have the little screw valve on the carb completely closed then backed out only one revolution. It is a brand new carb. Also there is spark from my spark plug. I try to start it with the choke open and also closed. Any help or advice would be greatly appreciated. I am very handy but as I said earlier not exactly an expert in this area. Thanks for any replies.
 

wayne z

Active Member
Dec 5, 2010
1,743
5
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louisiana
Sounds like you've got the basics down good. Be sure that you have very fresh fuel in the tank AND carb. Check the intake gasket for air leaks.

Could it be that the crankcase is flooded? Try purging the crankcase by removing the sparkplug and securely ground the plugwire away from the head and carb.
Then, with the batt charged good, spin the motor over for about four 15 second runs, waiting a little between runs. This pumps air throughout the engine to dry it out. Then try to start it normaly.


What type carb do you have? If it has only screw adjustment, thats useualy the idle throttle setting, not fuel adjustment.

In case you don't know, you should never tighten or loosten anything on the engine while it's hot or the aluminum threads will suffer.
 

Youngster8

New Member
Feb 9, 2011
5
0
0
NY
the plug does spark. I tried taking the plug out and letting the engine turn for a while to dry it out like suggested. When that is done i get it to run for a couple seconds but then it bogs down again and dies. Seems like it keeps on getting flooded every time. Is there any other reason that would cause it to flood? The carb has a throttle adjustment screw and only one other screw adjustment on the side which I am guessing is for fuel intake.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
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up north now
If the screw is a pilot screw, you will need to turn it out to make it leaner. If it's a "regular" mixture screw, in to make it leaner.

Sounds like it's too rich.