Mirage BTz charging.

M

Mark sav

New member
Location
Kent,gb
Engine running great after full rebuild ,but gen light staying on and not charging! Removed and checked ac voltage across the two pairs of output wires and only have between 11 to14 volts at revs. I have pulled coils off stator plate and found one trapped and squashed wire but not broken and coils look good ! What should be output voltage and coil resistance please ?
 
Resistance of the coils is in 0.x Ohm range, vaguely remember 0.3 Ohms on mine, so next to nothing. Did you measure voltage with the multimeter in AC range and coils disconnected from the R/R unit? Airgap of coils to alternator magnets should be not much more than 0.5mm.

Regards,
Stefan
 
Thanks Stefan,I measured voltage in ac with wires disconnected from rr . I measure 2.4 ohms on one coil and 2.5 on the other with self ranging fluke meter,and neither are going down to earth.flywheel magnet seems strong.did not measure air gap though. Any ideas?
 
Hmm, hard to tell, Mark. I'd consider that coils as pretty much bulltetproof in that application, but only 11 to 14 Volts AC with no load on them sounds a bit low. Probably something might have happened when you disassembled the coils from the base plate. You can check air gap w/o taking off the flywheel by poking a feeler gauge through one of the flywheel holes . Both coils iron cores should also sit on the same height. Often overseen when converting HKZ igniton base plates to BTZ mode, that some washers are needed under the second charging coil replacing the former charge coil of the HKZ, to have that coil at the proper height. But yours seems a generic BTZ bike, so don't know if this is the same on those ones, too.

Another issue could be how the coils are wired into the alternator. If the wires of one coil are accidentaly swapped, this will eliminate their output current to nearly zero.
 
Mark - exactly how did you measure the AC voltage output from the coils, and at what revs?  11-14v AC is too low...and is suspiciously close to DC charging volts!

I'm hoping you disconnected the charging coil wiring at the terminal strip at the back of the petrol tank.  Doing that, measuring across each coil in turn (yellow and yellow/black) should give around 25v AC at 3000rpm.

Did you remove the coils /wiring from the stator plate during the rebuild?
 
Thanks for your input. I did remove the stator assy during rebuild but did not strip it down. I measured voltage between both yellows to both yellow and blacks disconnected from rr. On ac. Scale ,no reading on dc as I realised after trying first ! I will try one to one later to see what I get from each coil.  I am no stranger to electrics but a bit baffled by this.
 
Mark, you might also check the resistance of the coils to each other. I had recently a stator plate in for rebuild, and insulation was not only found brittle on the pickup wires, but also on the charging coil wires, insulation snapped off like glass on slightest movement.
 
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