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P.J., Technician
Category: Motorcycle
Satisfied Customers: 750
Experience:  10 years as a mechanic and fabricator in a privately owned, local, custom bike shop.
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I have an 03 custom with a tc 88 ignition and I was doing

Customer Question

I have an 03 custom with a tc 88 ignition and I was doing some head work got it all together and went to start it would hardly turn over so I put a jumper box on it and it fired right up then it just died so I checked spark and nothing
Submitted: 1 year ago.
Category: Motorcycle
Expert:  P.J. replied 1 year ago.

It sounds like your voltage drop is too much while cranking to allow the ignition to fire.

The voltage cannot drop below 10 volts at the ignition or it will not create a spark. It can be tricky to measure unless you have a digital multimeter with a record function. Verifying this voltage would be the first check to make.

I hope this helps. Thanks, P.J.

Customer: replied 1 year ago.
I put a brand new battery in it still nothing would putting the 35 amp jump on it harm the tc88 or cps or coil?
Expert:  P.J. replied 1 year ago.

Jumpstarting will not harm the coil or crank sensor. Corrosion or loose terminals will also limit voltage to the ignition.

Check for the voltage on the center terminal of coil (depending on what you coil you are running). I'm assuming it is a 3 wire coil. You want to know the voltage with the ignition turned on, during cranking, and while running (if it starts).

The bank angle sensor (if you are also running it) can kill the ignition as well. If it isn't secured in the proper orientation that may be the issue.

If all that is good I can help you check the crank sensor. You'll need a meter with an AC setting.

Thanks, P.J.

Customer: replied 1 year ago.
Is the crank censor located next to the cam plate
Expert:  P.J. replied 1 year ago.

If the engine is also an '03 model then the crank sensor is located near the end of the oil filter in the lower left side of the crankcase.

If it is an earlier year model there may also be a cam position sensor located in the middle of the cam cover.

Thanks, P.J.

Customer: replied 1 year ago.
It has both
Expert:  P.J. replied 1 year ago.


To test the two wire sensor you'll set your meter to AC volts. Probe into the wires (it doesn't matter which order) and crank the bike. You should read between 1 and 3 volts AC if it is good.

To test the three wire sensor you'll first determine which wire supplies 12 volts DC. Then determine which wire provides ground. Now probe the third wire and, while cranking, you should read between 9 and 12 volts DC if it is good.

Thanks, P.J.