Chasing Electrical Gremlins: A Quick Update on the Spark-less Honda Elsinore

Salem Race PosterThe second Salem flat track motorcycle races are coming up on November 25th, and everyone knows that if you go back for that third helping at Thanksgiving you’re going to lose 1-2 horsepower on the turns because your rear fender will be rubbing on the back tire. With small displacement, you gotta slim down to speed up!

The last we left the Elsinore, it had rolled to a stop after the first lap in the second heat. No spark, not even an erratic one. Dead.

In Portland the rain has been relentless, so with the help of my wicked awesome girlfriend, we moved the Elsinore up onto our porch so I could wrench without getting soaked.

After running through the old wiring harness, testing the coil, stator and finally hooking up a 6v battery to the harness (and melting a ground wire), I think the problem is the rectifier. The points looks fine and the fact that I have zero spark points to a larger failure. The stator is pushing AC but I’m not getting an voltage out of the black/white wire… which should be 6 volts of DC heading to the coil and condensor.

honda-mr250-rectifier
Please be dead.

This rectifier is different than any I’ve seen before — mainly because a separate green ground wire is running to it rather than grounding through the mount and into the frame. That only leaves two wires – one from the stator (black/yellow) and one returning approximately 6 volts of power to the rest of the system.

Luckily Oregon has a couple secret weapons when it comes to vintage electronics. One of them is Oregon Motorcycle Parts. I’ve purchased a few things through Tony, and his parts and electrical knowledge are both tip-top. I emailed him and he’s building me a rectifier as I type this blog post.

I really hope this is the issue. When I first purchased the bike I actually emptied water out of this rectifier, and it certainly looks like the original equipment. 40 years is a good run for a piece of electronics, let’s hope that the new one returns spark to the system.

About that system. I’m rebuilding it from the ground up. The wiring harness is dead simple, but it’s also old with cracked insulation, stiff connections and corroded grounds. I’ll be running new wire, eliminating the headlight system completely, and tucking it all up a little neater than it was. This was something that I figured I’d get to after the season was over, but I’m happy to do it now if it ensures a strong running 6 volt system.

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I use real bullet connectors and a ratcheting crimper with my wiring harnesses, and it’s the best investment you can make if you do any custom wiring on your vintage bike. Quick connectors are great in a pinch, but do it right if you are building something that you want to last. I got my kit from Vintage Connections.

I also ordered a new coil, just in case. That should cover it – if I don’t see a bright blue spark you’ll be able to feel the heat from my frustration from Mt. Rainier.

I’m also using this downtime to get rid of some of the surface rust that was on the exhaust pipe and respray it with High Heat Rust-oleum.

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BEFORE: Light surface rust, but I didn’t want it to get any worse.

I took some sandpaper and a wire wheel to the worst parts, which were right at the first bend where the pipe meets the head.

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After one coat.
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I ended up putting two coats on after this photo.

I use this BBQ High Heat flat black paint on my Vespa Primavera pipe every few seasons. It should work just fine for the rest of the winter, and I’ll do something a little more permanent after the season.

Small things like this really make a project feel good, even when I’m in a bit of a holding pattern as parts get shipped. I like taking the time to clean up or repair a part that doesn’t need it yet, but is preventative in nature and makes the whole bike look a bit better.

I ordered some stainless steel springs to complete the exhaust clean up. Along with my electrical parts, I should have a whole mess of stuff to do when I get back on Friday.

Fingers crossed, updates then.

I’m starting to update my Project Pages – where you can see all the resources I’ve gathered and read all the posts pertaining to individual projects like my racing Honda Elsinore. You can view that page right here.

 

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