Ok guys I am new on here looking for some help. I have read through previous post on the site and have tried everything and still can't figure it out. My nephew has a Buyang 110 that will not run. The bike will turn over but will not start. The spark is weak and the positive and negative leads on the battery get really hot while trying to crank it. Any help would be appreciated. Thanks

 

Take a good look through your wiring harness to be sure none of the wires are bare or in bad shape,theres several others on this site that could probably pin point the problem but I would do that till someone tells you what else to check.

 

I pulled the complete harness out and checked all of the wires, all of them were fine. Thank you for the help

 

Diagnosing weak spark is very subjective and often wrong. Often this diagnosis is out of frustration after everything else while fuzting around has been tried and that's the only thing left. Weak spark is very rare, and can often be seen with meter tests. Let's put this on a back burner until all the more common stuff has been ruled out


Really? This is strange. How long did you crank the starter to get hot terminals? Both terminals got equally hot? Was the starter motor hot too? Hot terminals are not right. But notice the symmetry. You didn't have "one" hot terminal (which would indicate a bad connection). You had two terminals acting the same and pssing the same current. That suggests you're drawing too much current, or you're drawing current for too long. Starters are short term use devices. One minute of cranking must be followed by 10 minutes of cooling.

What is the history of this quad? Ever seen it run in your presence? When was the last time the valves were adjusted? Have you measured the compression? Does the starter motor crank the engine over at normal speed, or is it slow? Have you tried jumping your quad battery to your car using jumper cables (please take extra care to get the polarity right when doing this)?

 

I have never seen it run. It was given to him from a friend who lost the remote kill switch and never messed with it after he lost it. The both terminals get hot after 15 seconds of cranking. I haven't tested compression because I do not have a compression test. The motor turns over real slow unless I have the spark plug out. If the plug is out it turns over normal. I haven't adjusted the valves yet

 

So the battery terminals get hot. What about the wires feeding starter motor? Do they heat up too? There are three possibilities that I see. One is two bad battery connections (not very likely for two simultaneous bad connections). Bad connections under normal starter motor currents (roughly 30 amps) can get really hot and make the starter motor turn slow. The second possibility is the starter motor is bad. It could be dragging inside, or have a shorted turn in a winding that causes it to have low torque and draw massive current. The third possibility is that the engine is too hard to turn, and the starter motor is drawing too much current because it is overloaded with an engine with too much friction.

If just the terminals get hot, and not the wires going down to the starter motor, then try inspecting/cleaning up the bad connections. Take a meter and measure your battery voltage right on the battery terminals. Then measure the battery voltage at the starter motor between the starter motor input post and the starter motor case. What do you measure for both of these tests?

Pull out the starter motor and see if is spins freely when pressing the start button with the motor disconnected from the engine.

Rotate the engine by hand. Does it turn freely?

 

Yes the wires to the motor and the starter get very hot also. The motor does turn freely, I will have to try everything else tomorrow after work.

 

Ok got alittle time to work on it. Only the positive wire coming of the battery to the solenoid and to the starter is getting really hot (melting point). I pulled the starter so that it could turn freely and the positive side still got hot. Ideas?

 

does it have an inline fuse at the battery? if so, what size? should be about a 7amp. no bigger. check your battery cables for loose connections or corroded connections. that'll build heat. what it is doing is you're sending the electricity down the wire and it can't send all of it due to a wiring deficiency. whether the wire is broken, kinked, or loose, the electricity can't pass through it for some reason. we gotta find that reason. so the starter turns freely after you pulled it? did both battery leads get hot? hmm...if it ain't making it to the starter very well, something is going to ground on the positive circuit.....hmmm....let me think......

 

The fuse is a 7 amp. Yes the starter turned freely but the positive lead gets hot. When the starter is installed on the bike, it acts like the battery is dead and doesn't have enough power to turn the starter. The motor itself is easy to turn by hand. I have checked all of the connections and can't find anything wrong. I pulled the entire harness out of the bike and checked everything. Would a bad starter cause this?