Workbench October 2014

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stu and bike

Technical Questions and Answers

Voltage Concerns


Well, I went out to get a fuse for the .300 A scale on my good VOM while leaving another in series and when I came back about an hour later, the drain was maintaining at a consistent level. I switched meters without losing the connection and it maintained the same, so after about 15 minutes I started to test things and started with the easy stuff: the plug for the readout controls under and in front of the key. I pulled it out and nothing changed. I put some dielectric grease on it and plugged it back in and noticed nothing, but by the time I had moved to the back of the bike to start checking out the wiring in the trunk hinge area, the meter started varying and then dropped to .00495 A. I’m not sure 1) why dielectric grease would make a difference when being completely unplugged made no difference, and 2) why it would change after 2-3 minutes of being plugged in. I’m going to keep it on the charger when not riding and check it every couple of weeks to see if it starts drawing again.

In another vein, I may have an idea of the cause of the decreased fuel mileage subsequent to this winter’s work of replacing the preload with the one you rebuilt for me, but it depends on your answer to the following question. Does the inherent error in the speedometer show in the odometer as well? The reason that this matters is that my daughter gave me a SpeedoHealer for Christmas and that was installed while things were opened up. The adjustment was .066 to true the speedometer up with an accurate GPS. This change would cause one factor for sure, my driving faster (higher rpm) due to the speedo actually being accurate. The question above figures in because if the installation also impacted the odometer, recording the true mileage would have reduced my mileage by 6.6 percent, and if I add to that the increased time over 3,000 rpm, I can easily see myself getting to the 10 percent-plus decreased mileage.

So, what do you think of my hypothesis?

Van F. Moore
Salem, OR

Hi Van,
AHA! The other half of the story (that I usually never hear). You’re correct that the rpm at any particular cruising speed will now be higher. For instance, your tach probably registered right around 3,000 rpm at 70 mph indicated (63 mph actual) and now reads around 3,300 rpm at the same indicated (and true) speed. Depending on various things such as windshield size, externally mounted wind management accessories, etc., I suppose a 10 percent reduction in fuel mileage would be possible due to increased wind resistance alone, which also increases engine load. Regarding the odometer, I’m sure it was affected as well. In fact, when the GL1800 was a fairly new model, some owners expressed extreme outrage, claiming the odometer reading higher than actual mileage affected their warranty. After I reminded them that the warranty wasn’t predicated on mileage, the squawking largely stopped.

As for the delayed reduction in parasitic current flow, it actually could be explained by the dielectric grease. The GL1800 will exhibit a higher than normal parasitic load for a short time after the battery terminals are first connected. I’m not certain what component is responsible for that, but it may be something in the display. Your playing with the connector may have corrected a faulty connection. Check the back side of that connector for loose wire strands that may have been creating a partial short to adjacent wires in the connector. Dielectric grease packed into the back side of the connector is intended to reduce this possibility.

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