Hi All
The head light on my 250 A suddenly stopped working with also main beam indictor display. This is also causing the rear light to flash when the indicators are on. The obvious course of action was to check for any bad earthing, but all earthing felt OK with fuel tank off. I am reluctant to really delve into the wiring loam any further and hope someone can shade some light on this for me please?


Kind Regards 

I prob have more questions than answers, but...

I would pull headlight out, crank engine and test output voltage at the headlight connector to ensure you have a working *lighting coil and check battery voltage. Check ground to frame at same connector. The fact that the turn signals/tail light work off of the battery, makes me question whether enough voltage is there to support the turn signals, thus dimming taillight as the indicators come on/off.

not sure what you mean by main beam indicator display.

Main beam indicator display probably refers to the red high beam warning light in/on the top of the headlight bowl.

Have the clocks backing lights stopped working as well?

You can check the bulbs by wiring them direct to a 6v battery. If the bulbs have all blown then, as well as a new headlight, you will need to fit a 6v voltage regulator.

Thanks for your replies, I shall check on that but where do I get a 6V voltage regulator. The lights on the gauges are OK. The bulb is new and checked still intact.

Regards

I don't have time to post any links now, but they often turn up on fleabay, with wildly varying prices.

They are single wire - the wire looks at first glance to be yellow but, I think, is yellow with a white stripe.

Yamaha made a couple of versions - look up DT and XT models, from 1976 onwards, on CMSNL for images of what you should be looking for.

 

how about item N0, 134377140918 on ebay or 373521466904 my bike is 1974

Thanks a lot

First item is a rectifier, not regulator. Second one MIGHT be a cheap and nasty generic one (quality is impossible to determine nowadays).

This is what I would fit, though I'd want it cheaper.

Yamaha XT500 Regulator | eBay UK

DEET once did a test on voltage regulators.   The one-wire OEM Yamaha regulator was the only one that actually worked properly.   The "look alikes" did not regulate very well.  

Years ago, I tried a "look alike".  It looked really nice and came in a pretty finned case (as did some of the Yamaha OEM versions).  DEET had not yet published his test video as I remember but he warned me on the old forum that the regulator I bought did not work very well in his tests.  I should have listened! 

Since then, I've only used OEM Yamaha which can often be found used pretty inexpensively on ebay by sellers that don't know what they are (I've seen them listed as "CDI boxes" and all sorts of "guesses").  I've never had a bad used one and usually pay $10 to $20.

The other DEET option was a 3 wire 6v AC OEM regulator used on Vespas et al, if I remember correctly.  They were still available new for about $40 (which is a lot cheaper than a new OEM Yamaha regulator!!!!).   DEET made a neat little wiring harness to adapt those quality regulators and sold them...  he still might?  It's a great option if someone wants New and wants something that will actually work well!

P.S.  A bit of trivia is one of the very few times Mako (website owner) had to step in and censor/delete posts and close a thread was when a vendor attacked DEET for daring to actually test several available aftermarket regulators...  none but the Yamaha OEM one-wire and Vespa/Scooter OEM 3 wire passed if I remember correctly. 

 

Without reading comments yet--headlight power comes via the dip switch after the main switch. Might be a clue there. Just earth the bulb socket to a secure earth then umm thinking-- run a wire from instrument blue to the headlight bulb high or low , or both. Instrument blue is magneto powered as is headlight. Just thinking though with headlight not working but instrumentes are, it must already have a regulator somewhere or your instrument bulb s would be shot.

I'm wondering if the headlight stopped working because the engine isn't running?