Hi folks,
Ill start with apologizing if I have violated any of the posting guidelines of this forum.
Im just in need of some help to save a motorcycle.
I’ll start by introducing myself and keep it as short as possible. By day I’m in the custom metal fabrication trade, automotive sub category, automotive engine performance sub sub category? Tig welding 95% of the time. 15+ years experience and still learning. By night, avid FPS console gamer, Netflix connoisseur in training and sleep procrastination analyst? I’m no expert in anything above.

My issue at hand. I have a 40+yo motorcycle that I custom built into a cafè racer/bobber. I built/designed it to my liking. Well recently (5 weeks) an important electrical part has an intermittent failure resulting in a dead bike for a few minutes. A new bolt in replacement part doesn’t exists either from NOS source, dealer or aftermarket supplier. There’s no aftermarket upgrade as well. The part in mention is the pulse coil. I’ve scoured the www to great lengths for the past 3 weeks trying to find at least an equivalent part that I can use as a replacement but the coil ohms rating and its pole shape are making this scenario that much more difficult to get past.
The information I’ve gathered from the repair manual is that it’s a variable reluctance type coil that should have 360-520ohms of resistance between its 2 wires. The pole shape on mine is a vertical line (not sure of the correct term but picture a flatblade screw driver and that about sums it up) Ive purchased a 2 vr coils from that I’ve found from 2 different donors both of which ended up having low resistance. My questions are..
Is it possible to increase the resistance of any particular pickup relatively easy?
If anyone has info of a vr sensor within the specs above, that would be greatly appreciated.
Took me some time to post this, kept getting sidetracked. If you need more info, let me know here. Thank in advance...

 

Is it possible to post a pic of the VR sensor?
Is it possible to reverse engineer it?
They are basically simple devices, is it an intermittent open maybe?
Max.

 

Yeah it’s intermittent. The bike starts just fine and can even ride it on the freeway. But will die soon as I’m stopped at a light long enough for the heat to catchup to the pickup since it’s an air cooled motor. Same goes if I let it idle for 10mi s after a cold start up, the same results happen. After a couple mins of cooling, motor starts back up as if nothing was wrong. Bench tested the pu using a heat gun and was able to recreate the problem.
This is a pu From a Polaris sportsman I think. Had to mount it upside down in order for the pole to be inline with the rotor. Unfortunately this one only has 129ohms of res. The motor gets a weak spark at best.
Below is exactly how my pu would look if brand new.

 

a variable reluctance type coil that should have 360-520ohms of resistance between its 2 wires

With a resistance that high the coil clearly has a high number of turns of extremely fine enamelled wire.
Apart from the mounting, the coil resembles a read/write head from a tape recorder. I wonder if a salvaged tape head, in conjunction with a magnetized rotor, would do the job?

 

I tried the search function here, but it seems a lot different than what I’m used to on other forums I’m on. All that comes up is the same info I’ve seen linked from other forums. Some seemed promising, but never concluded the outcome. It’s been 9 years on some?