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Clubroom => Tech Talk => Topic started by: tdpomodoro on September 10, 2012, 07:30:19 pm

Title: Yamaha DT175A (1974) Stator - What's the 3rd coil for?
Post by: tdpomodoro on September 10, 2012, 07:30:19 pm

I've started to tinker with my lighting coil. I removed it a couple of years ago when I first got the bike. After inspecting the stator plate yesterday I noticed there's two more tapped holes to accommodate another coil. I wrote it off as something Yamaha has done to economise spares, sharing stators for different bikes.

Then I came across the following image:

(http://i7.photobucket.com/albums/y269/tdpomodoro/2350914820087740812S600x600Q85.jpg)

So,

- 1 off coil for ignition
- 1 off coil for lighting

What's the third one for, also ignition? Does it have anything to do with higher RPM's and sparking?

Why i'm so perplexed is that my bike currently starts and runs fine....albeit I haven't really opened her up except for a session at Barleigh Ranch where it was so out of tune it was oiling something fierce after a couple laps which i put down poor needle and mixture settings - I also didn't de-oil my air filter......

This makes me wonder if I need that additional coil??

Title: Re: Yamaha DT175A (1974) Stator - What's the 3rd coil for?
Post by: tdpomodoro on September 10, 2012, 07:39:16 pm

More digging:

boats.net tells me that it appears to be a second lighting coil.

http://www.boats.net/parts/search/Yamaha/Motorcycle/1974/DT175A/FLYWHEEL%20MAGNETO/parts.html (http://www.boats.net/parts/search/Yamaha/Motorcycle/1974/DT175A/FLYWHEEL%20MAGNETO/parts.html)

Perhaps 1 coil is left as AC to drive the headlight directly, and the other is rectified and used to charge the battery and all the other lighting demands.

Title: Re: Yamaha DT175A (1974) Stator - What's the 3rd coil for?
Post by: Tim754 on September 10, 2012, 07:59:05 pm

Yep :) You have seen the light!