Hi everyone.

I purchased this bike for my son, prior to him taking his test, for some road practice. However it was running fine (well as fine as these bikes do) He parked it up, when he went to start it again - there was no spark. Tried a few various things, changed spark plug, checked kill switch wasn't stuck, bump start - nothing. We then handed it to our local mechanic. He checked the same as us, most of the connections were starting to corrode and they have cleaned them up No actual breaks in wiring. But he cannot find the correct OHMS readings for the Pick Up Coil and also the CDi unit. So still no spark.

Any suggestions/or OHMS readings would be very much appreciated.

Thanks everyone

Joe I doubt you will find anyone knows unless Haynes did a manual?

You didnt mention the stand switch? did you test that was making and breaking with your meter?

I've got a Yamaha service data book that says TW125 1999 and onwards

Pickup coil Resistance 656 - 984 ohms across the Red and White Wires

Source Coil (CDI Charge Coil) Resistance 624 - 936 ohms across the Brown and Green Wires

Yamaha never used to give any figures for the CDI unit even in the Genuine workshop manuals so it was a case of making sure the other tests checked out OK before replacing the CDI

Hope this helps. Tony

testing CDi units requires a special test set, you can't do it with a multimeter.

We have this equipment and can test your CDi

www.rexs-speedshop.com

Hi Tony,

thanks very much for that info. I will pass it on to the shop in the morning and see what happens from there.

Lisa

I've got a Yamaha service data book that says TW125 1999 and onwards

Pickup coil Resistance 656 - 984 ohms across the Red and White Wires

Source Coil (CDI Charge Coil) Resistance 624 - 936 ohms across the Brown and Green Wires

Yamaha never used to give any figures for the CDI unit even in the Genuine workshop manuals so it was a case of making sure the other tests checked out OK before replacing the CDI

Hope this helps. Tony

Hi Speedshop,

My mechanic did mention that you needed specialist equipment to test the CDi. But was not able to give me any prices. Can you give me an idea of the costs involved please. I think you can PM me on this forum, if not you can email me.

Thanks

Lisa

testing CDi units requires a special test set, you can't do it with a multimeter.

We have this equipment and can test your CDi

www.rexs-speedshop.com

would u sell the tw125 as i just passed ma test thanks