Hello all,
I've got a recent issue with my 75 850.
It started about 3 months ago. The Bike died on me after about a 40 mile ride.
I left it set overnight and it fired right off.
I figured the stock coils were tired so I replaced them.
The bike starts fine (like it always has) but will only run for about 10 minutes before quitting.

I'm now thinking that maybe my 17 year old Boyer is giving up the Ghost.

What do you think?
Does this sound like a dying Boyer black box?

wild shot, blocked tank vent?...someone here will put their finger on it.

Take a look at the pick up plate (where the points used to be)where the wires attach. I had an issue where the wires got brittle and broke.

I just finished pulling the pickup plate and doing a continuity test on the wires from the box to the plate,
all is A-OK.

Yes - all is OK now, but what about when it is hot? I agree with the "wiring" boffins, above - my 72 with Boyer would consistently run for about ten minutes, then quit until cool. My particular ogre was one of the Boyer wires inside the timing chest - the wire would lose continuity when hot, but worked fine when cool. You will have to chase the electrons when the wires are hot to be sure you have continuity. THEN, if all is well, try other stuff. However, this sounds so identical to my previous problem, I am betting on bad wires as the source of your aggravation.

I am unfamiliar with the boyer ignition however this sounds to me like you are losing your fuel flow due to a blocked breather in the fuel cap. Next time this happens immediatly and slowly open the fuel cap. If you hear a hissng noise the fuel vent is blocked. I hope this helps.

Its an ole motrocycler's prank to drop rag in tank so starts fine but 10 min later rag shuts er down, ditto ditto etc, so peek in just to relieve us all. Leave cap loose instead of trying to catch it before stalls and if it don't bingo!

I've also had water in bowl do that, start ok but then misfire when warm and stall. Of course there should be no ballast resistor in power to Boyers or other electro brains or lowers V when warm so Boyer losses it timing brain function. Its also possible broken copper inside installation that flogs and separates once warm but checks fine cold and static.
Trigger wires most infamous for this as mentioned.

Mark wrote:I just finished pulling the pickup plate and doing a continuity test on the wires from the box to the plate,
all is A-OK.

Unless the insulation is cracked 360 deg. at the entry , and goes silly occasionally .Theres a wire under VH Holdens does this at a clip to a tube , at the wreckers THAT wire was Cracked on all of them .Easy one to spot .

HENCE the ' Replace Every accessory wire ' advice , or at least inspect thproughly . Whadabouthe Condensors .

This sounds like a classic case of the Boyer stator wiring. Where they are attached to the plate and are encapsulated in resin they tend to break. It's usually intermittent like you're describing. I don't think I've ever seen one last 17 years without failing this way. An elegant repair is to scrape away the resin de-solder the wires and solder screws on as posts to which to attach the wires. Someone on the forum (Norbsa I believe) sells a small kit with everything you need to do this. It's a quick and easy repair and something Boyer should have done many years ago.

I also had this problem, and found it was to do with the key switch. If it happens just try wiggling the key. I replaced the switch now no probs.

Nelson wrote:This sounds like a classic case of the Boyer stator wiring. Where they are attached to the plate and are encapsulated in resin they tend to break. It's usually intermittent like you're describing. I don't think I've ever seen one last 17 years without failing this way. An elegant repair is to scrape away the resin de-solder the wires and solder screws on as posts to which to attach the wires. Someone on the forum (Norbsa I believe) sells a small kit with everything you need to do this. It's a quick and easy repair and something Boyer should have done many years ago.

With the continuity test, wiggle the wires and you might find a break inside the insulation just before they are soldered to the stator plate. Install new stator plate and drill it, bolt the wires on and use nyloc nuts to ensure vibration proof. There is a nice info sheet somewhere on the Internet explaining the process nicely, and it worked for me. I did find the break in t he wire eventually, but it would show continuity and randomly no continuity as it was wriggled.

My problem was that it would start but suddenly start backfiring and running on mostly 1 cylinder and fowling the plugs. Further oil analysis showed 1% fuel in the oil (caused from running home on 1.2cylinders more than once with bursts of 2 cylinders along the way ( as if trying to convince me she had just cleared a fuel blockage or something).

Once I confirmed the broken wire, I resoldered the stator plate real good and thought the problem was fixed. It cam back 100k latter exactly the same wire, broken inside insulation again. Second time I replaced stator and drilled and bolted connections. I also replaced the black box while I was at it.

Now she is running and starting like a rocket. Just fixing other stuff like broken throttle cable, etc etc....

The wires on mine broke under the zip-ties. Using the rubber sleeve 061093 might help, but in the end I just made up the posts. I believe Boyers were originally set up this way.

Gosh its been a long time since I last saw the back side of a Boyer, ugh.
ReGardless of what combo of things you find preventing constant joy those Boyer trigger wires Will break soon enough so while its out and on you mind do your self and bike innards a big favor and DIY upgrade them or ping here for the easy way out if following instructions to a Tee. Greg Fauth Norton Bsa <norbsa@hotmail.com>

I don't think that I need instructions.
After seeing rpatton's Pic, I see what the mod is and I can do it no problem.
I'm gonna re-wire the whole thing like 1up3down suggested and see if that fixes the issues that I have been experiencing.

If not, then maybe I'll just have to spring for one of those Pazon units.
.