[mtgox]

Most common cause: Running rich
Running rich (too much fuel in the air/fuel mix) could be caused by several things. The most common cause is a failing automatic choke unit. The choke on the GX150 carburettor is actually an enrichening circuit and in reality does not choke off any airflow at all. The auto-choke is ON in it's natural state. A failing auto-choke remains in the ON position at all times, thus it is characterized by the buggy running fine when cold, and hardly running at all when warm. [links]

[Galuel]

Bogging down is usually caused by one (or more) of three things. Running rich, running lean, or a weak spark.

[kenny1029]

I'll start off with a very brief explanation of what Air/Fuel mixture is. The job of a carburettor is to atomize liquid fuel by injecting it into a flowing stream of air. The mixture of this air and fuel must be rather precise in order to combust within the cylinder. If there is much air, or too much fuel being delivered you will experience power loss and/or bogging down. With that said.. lets get down to the troubleshooting: more

[drwhite]

Running Lean
You may be running lean (too much air in the A/F mixture) if you are: 1. Having a hard time getting the engine started, 2. Once started the throttle is very tricky, too much throttle and the engine dies, and/or 3. Engine bogs and will not go beyond a certain RPM. This is commonly caused by a deteriorated intake inlet manifold. This inlet manifold can be found connecting the carburettor to the intake side of the engine. This little elbow-shaped inlet can form dry-rotting cracks, thus becoming a major vacuum leak. Please note: when replacing the intake inlet manifold, do NOT over tighten the nuts when securing it to the cylinder head. more

[shadowdust]

Weak Spark
If the Air/Fuel mixture getting to your engine seems fine, then you may be looking at a weak spark. Ignition troubleshooting will be covered in detail on another page. The basic rundown is this: Stator/trigger wire -> CDI -> Ignition Coil -> Spark plug. It is best to check the resistance of the parts in question. Check the Yerf Dog GX150 Service Manual to find out the correct resistance values.

[paulkeogh]

Overheating can occur when the power quality is poor or when an electric motor is forced to operate in a high-temperature environment. more

[david345]

Luckily, preventing contamination is fairly easy. Main sources of contamination include dirty tools, work areas and hands. Motors can also be contaminated by foreign matter in lubricants and cleaning solutions. here

[endian]

With the right equipment, these tests can be performed without taking the motor off site, thus minimising downtime. [links]

[becauseIfuckingCANbitchz]

How long do electric motors actually last before they break down? The answer is often disputed, with some manufacturers stating 30,000 hours and others suggesting they can power through for up to 40,000 hours.

[tomdetroit]

If this would be the case, motors as we know now would probably not exist. more

[SelfHelp]

At steady state, the electrical power input to the motor is exactly equal to the output mechanical power at the motor shaft, minus any losses. here

[matsh]

motors produce heat mostly by electric resistance, so heating is proportional to the current flowing through the motor, current is basically proportional to torque, so that increases with load too. [links]

[Symbiosis]

Don't let inductive current lag (apparent power) confuse the issue. Ohm's law still applies.

[Odin]

Walking Belt is Worn:

[mgoodn2244]

The step to test for the motor is to use a foreign object preferably on a long shaft. First determine the direction of the motor spin (most have directional movement printed on the motor tag), then apply pressure with an object with downward pressure on the flywheel in the direction the flywheel is turning (do not attempt to put force against the rotating direction of the flywheel as you can easily injure yourself). If you can slow the motor, typically you need brush replacement.

[Xaxo]

The only certain way to test for a worn walking belt is to take a DC amp draw (if you have a DC treadmill) or an AC draw (for AC). Trying to look at the belt or a feel test is highly unreliable. Better tests, if you lack a DC ammeter (they are expensive for a good one), are a coast test or an incline test. To test the deck, go back to the Troubleshooting section and download the belt and deck inspections
instructions.