The New And Improved Unofficial R65 Forum V2
General Category => General Announcements => Topic started by: jusgus on February 25, 2012, 09:39:20 AM
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Disclaimer: The subject of this article is a device that I invented and made. I have used the device to set the ignition timing on my 1980 R65 BMW motorcycle, and I have found it be accurate when rechecked with a proper timing light. The motorcycle still has its stock ignition system consisting of coils, condenser and points. To the best of my knowledge the bike has suffered no ill effects from the use of the device. Because I do not understand exactly, the electro-magnetic principals involved in the operation of the device I cannot warrant that it will not cause damage to other motorcycles. Also, the Tool Kit Timing Light can never replace a real timing light. By comparison, at idle speed it is blurry, and above 3000 rpms there are no less than 6 ghost images behind the advanced mark. It is what it is; a small inexpensive device that will help you set the timing on your bike in a pinch.
When I bought a used 1980 R65 several years ago, it did my old heart good to dust off the timing light for her regular tune-ups. On the down side, I had a hard time looking around the timing light to see the timing marks through the hole in the side of the engine housing.
I thought to myself, wouldn’t it be convenient to use a small light and place it inside the engine housing. That caused me to remember my first four wheeler, a used 1966 Chevy ¾ ton fleet side with a 200 cubic inch straight six. Back then I had a very inexpensive timing light that used the electrical impulse going to the number one spark plug to excite a neon strobe. It was not very bright but it worked in the shade.
The next insight came from an idea of Kevin Reimer’s. Kevin used two shortened spokes and lugs attached to the spark plugs of a BMW airhead motorcycle. The lugs were screwed onto the plugs and the ends of the shortened spokes were attached to the plug wires. Kevin then used a screw driver to short out one cylinder and then the other by touching the screw driver to the bare spoke shaft and the cylinder. This procedure was used to fine tune the carburetors. In particular this method worked for bikes with electronic ignition.
I have used a spoke as a core for the coil of the Tool Kit Timing Light. I first attempted to make a transformer to power the LED but the only way to produce a current in the coil was to use only one leg of the coil. At that point it seemed that the coil was an antenna. While working on the prototype it became apparent that the air gap between the core and the coil had a marked influence on the brightness of the LED. When this development was factored into the equation it seemed to indicate that the current for the LED was produced by an inducted capacitance. At least that’s what my big brother Jimbo told me and he ought to know. Anyway, it works and they are easy to make as you will see in the rest of this article.
How to make a Tool Kit Timing Light
Begin with an old spoke and lug.
Remove the lug and screw the small end onto the left cylinder spark plug as far as it will go (snug). Then screw the spoke into the big end of the lug until it bottoms out on the spark plug. Mark the top side of the spoke. Remove the lug from the spark plug being careful not to turn the spoke in the lug. Place the lug in a vice and bend the spoke at the top of the lug approximately 30 degrees in the direction of the topside mark. (Be careful not to crush the lug.)
Cut off the spoke about 2 3/4” from the lug and file or grind a slight bevel on the cut end of the spoke. Cut a 2 1/2” length of NAPA windshield washer / vacuum hose (part # NBH-H-459) and slide it over the spoke down to the lug. Wrap the hose with 3M 33+ electric tape. (The electric tape is vinyl but the hose needs to be rubber.)
Cut a length of Ace Hardware all-purpose Bell Wire 20 AWG single strand wire 60” long. Insulate one end of the wire with a small piece of electric tape folded over the end, and leave a little sticky showing. (The sticky will help hold the wire as it is wound into a coil.) Begin winding the coil with the insulated end of the wire about 1/4” below the end of the tubing at the cut end of the spoke. Make about 30 turns but stop at least 1/4” from the bottom end of the tubing.
Test the coil. Remove 1/8” of insulation from the running end of the wire. Screw the lug onto the spark plug and attach the plug wire to the bare end of the spoke. Start the engine, and then ground the coil wire to the cylinder. If the engine runs rough or the plug stops firing your coil is not working properly. (Most likely the ignition current is leaking into the coil wire.) If the engine runs smoothly after you ground the coil wire, check to see if it is making current. It should make a friendly little spark about 1/16” long and if you touch it you should get a tingle but not a jolt.
If the coil is good, check to see if the lead from the coil to the timing hole is long enough. It should reach easily with some slack and an inch or two to spare. Remove the coil from the engine
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Very ingenious and I like the idea of getting the LED in close to reduce parallax error which is quite significant on our small flywheel bikes.
I don't know about "inducted capacitance" though.
I would think it's simple electromagnetic induction. When the current in the ignition leads changes due to the ignition pulse the electric field changes and induces a current in the surrounding coil which lights the LED. The ghost images are probably oscillations of some sort. A Kettering ignition system has inherent oscillations in any case. The old neon tube strobes suffered from the same problem because they used the ignition pulse as an energy source while the modern xenon strobes only use the ignition pulse as a trigger and are able to filter out all of the noise.