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Parasitic Draw / Short at points

905 Views 4 Replies 4 Participants Last post by  Mydlyfkryzis
Hello Honda Twins,
I want to preface my first post with a disclaimer - I'm 18 and the only mechanically inclined one in my family - so troubleshooting this build has only been me, my climber manual, and the internet. Forgive my ignorance.
The previous owner of this bike had cafe racer goals but was a doctor rather than an electrician, meaning the bike has some funky wiring.
That being said, I've gotten the bike to the point where it starts and runs.

So onto the problem at hand:

When I turn the ignition on, immediately there is a ~2.6 amp draw that I've traced to the points. When they touch, there is a draw, when they are not touching, there is *not* a draw (wow, that's how electricity works!). This is what I describe in the video.

Is this problem with the points, wiring, or possibly a rouge ground/short?

I know the easy way out would be to just be to install electronic points ignition, but I admit to slight doomsday prepper leanings and in the event of an EMP, I'd rather have a working bike. Sorry :/

Any help or suggestions would be greatly appreciated!
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When a set of points are closed and the ignition is on, they complete a circuit to the coil. If left on too long, you will burn the coil up.
You have 2 sets of points which open and close independently. Not an expert on your bike but I believe that at any given time one or both sets of points is closed. You apparently have the engine stopped at a spot where the other set of points is open. In your video you say (and show) that you have a current draw when the points are closed. This is normal since the closing of the points is what completes the circuit and energizes the corresponding oil. When the points open it de-energizes that coil and the current through that coil stops. What you are demonstrating is the system working exactly as it's supposed to.

Welcome to the group.
Thank you both for your insight. If the bike is in fact wired correctly, then is it normal to have a ~5.3 amp draw while the bike is running?
My battery gets quite hot while the bike is running, and drains to around 8-9 volts within 20 minutes of operation.

I assume the recharging system (perhaps the stator) is amiss.
Yup, thats why many of us don;t recommend smaller batteries (in AH capacity). If your charging system quits, you have very little reserve.

And yes, the charging system is a bit anemic. They generally do not charge at amn idle. Full output is available after 5000 to 6000 rpm. Assuming the rest of the system is in good shape.

A Sparckmoto Reg/rectifier is a great replacement for the stock components. With better regulation and lower internal resistance, it allows you to get the most from the weak system. I originall used a Kohler Cloner replacement, which worked, but later replaced with a Sparckmoto unit. The performance was better with the Sparckmoto unit. Higher voltage (do to lower internal resistance) at low RPM, and very stable regulation when the system was putting out the full amount. I helped Sparckmoto develop the unit, so I have done a bit of testing. It is a superior unit at a competitive price.

Before replacing any components, though, it pays to clean and tighten EVERY connection in the charging system. Old, dirty connectors, loose connectors, can cause poor or no charging.

I bought crimpers and connections from OEM-Type Bullet & Spade Electrical Connectors for 1960's through 1970's Japanese Vehicles... Bridgestone, Datsun, Hodaka, Honda, Kawasaki, Landcruiser, Suzuki, Tohatsu, VW, & Yamaha and renewed/replaced the most important connections (ignition wiring and charging system) with fresh. IJn some cases I went a size up for better reliability. My bike chgarges and runs very reliably now.
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