QuestionI purchased this bike it was almost complete. After getting a few missing parts, I had it running briefly ( about 2 or 3 minutes. ) I was thinking " ok, it runs now let's clean the carb. out and finish up". After carb. cleaning, I had been moving back and fourth from one spark plug to the next with no luck. I noticed the cap was loose so I looked at the coil wire. Should it be turning some- what freely at the coil or could I have broken it off? How do I check the coil for function besides looking for spark at the plug? Timing and point gap are fine. Like I said, after having had it running once this is the conclusion I have come to: does it sound like a bad coil? Thanks, Jeff.
AnswerJeff, you have to have all the ingredients proper fuel at the right time, compression, spark at the right time for a running engine.
The spark plug caps generally just screw into the end of the coil wire. You might want to trim back about 1/4" to get some fresh strands to connect the cap to. If the cap is a resistor type, check for about 5k ohms. The coil wire should not be loose in the coil tower end. Honda coil failures are very rare. Put a test light on the coil points lead to see if it lights up when you are kicking it over.
http://www.cmsnl.com/honda-mt125-elsinore-k0-usa_model687/partslist/F++20.html
Points need to be very clean at the contact surfaces. Any dirt or corrosion will prevent the magneto from generating a spark.
If spark is erratic using a fresh spark plug to check, then the condenser may be the fault. You can check the coil with an ohm meter on the primary side windings (small terminals), which should read out about 1-2 ohms, I guess. I don't have specs on MT125s handy.
Make sure your #50 idle jet is open. 2 stroke engines can be plagued with either air leaks behind the magneto or they suck oil in on the transmission side, when crank seals/bearings have failed.
Bill Silver
