Vintage Dirt Bike Q & A

My CR125(CDI) has an electrical problem. I have a very weak spark at the plug(new) but I cannot find voltage anywhere else? Should I get a reading on something coming out of the mag? I have changed the stator, too? HELP!

I finally got the El to hit & start but it takes full throttle with choke on for it to barely run. Turn the choke off & it dies. I have cleaned the carb several times. Any ideas?

If you have weak spark, the CDI is bad. But it sounds like an air leak, from the manifold or bad crank seals.

alan

Here are readings I took off one of my CR125M ignition setups:

CR125M Ignition Readings (requires high-quality meter)

Stator Output @ 140VAC (narrow pulse - use peak-hold function)
Stator Pulse (trigger) @ 60VAC (narrow pulse - use peak-hold function)
Stator Output Coil Resistance @ 270 ohms (inductive)
Stator Pulse Coil Resistance @ 130 ohms (inductive)
Ignition Coil Input Resistance @ .7 ohms
Ignition Coil Output Resistance @ 10,600 ohms (inductive)
CDI Box Input Resistance @ 4.1 megohms
CDI Box Output Resistance @ 2.6 megohms

Do you have another working carb you can swap out?

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric