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Posted by scamp62
- October 29, 2014, 14:59:46 PMWill do !!!
Posted by Troll
- October 29, 2014, 10:08:12 AMplease let us know how it works...I'm sure everybody is interested.
Posted by scamp62
- October 28, 2014, 12:40:00 PMTroll your my hero !!! that all makes since !!!....thank you sir !!!
Posted by Troll
- October 28, 2014, 09:56:59 AMB+ simply means battery positive. This is a constant and will not change, so this is not what you want. There are two wires on each coil, beside the high tension lead. One coil has red and green and the other has red and black/white. Since the igniter is as easy to access as the coils, I would try connecting temporarily to that to see which one , if any, work. I can't say, for sure if this is going to work, since my W-650 has a similar system but there is a tach output on the igniter just for this purpose. If I get a chance, I'll stop by the dealer and ask how they would connect a test instrument. I'm surprised the tach didn't come with instructions.
Posted by scamp62
- October 27, 2014, 21:52:45 PMO.K. I will have to take another look at the coil, I only saw one lead, and the spark-plug lead, but I'm not an electrician (nor do I play one on T.V. !) what exactly dose B+, and pulsed mean, and which one do I want to hook-up to, are they marked ? ......as always gentlemen THANK YOU !!
Posted by Troll
- October 27, 2014, 20:49:13 PMI don't have a wiring diagram for the ign. on an 800, but you need to connect the tach to the ground side of the coil. One side will be B+ with the ignition on, and the other will be pulsed.
Posted by scamp62
- October 27, 2014, 20:38:29 PMSo were do you make the connection ?
and thank you for the help !!
Posted by Troll
- October 27, 2014, 19:07:15 PMthe tach signal is low voltage...actually a pulsed ground, so no, not the high tension side.
Posted by scamp62
- October 27, 2014, 12:08:48 PMOne last question gentleman ! (maybe ?)
The trigger lead from the tach is connected to the coil, I assume the they mean on the input side and not the spark plug side ?!?
Posted by Troll
- October 27, 2014, 09:35:24 AMWaste spark has been around for over 100 years. The Drifters are not dual fire, in the sense you are thinking. The 1500s are dual plug, however. This is both how and why it works: A spark coil when energized, is looking to get rid of the energy through discharge. Spark energy will only jump the gap with the least resistance. A cylinder with a burnable mixture inside will ionize and allow a path for the spark to jump, the cylinder on the exhaust stroke essentially does not have a burnable mixture, so no ionization, no spark jump. It's actually a pretty simple system to get a multi cylinder engine to run with only one ignition trigger. In the old days, a dual tower coil was fired by a single set of "points". Mid year 1978, H-D replaced the points with an electronic module, but the rest of the system dated back to 1911...This is essentially the same kind of system that cars had up until the digital ignition processors took over, and after distributors went away...I had this system on all my H-Ds, as well as on my BSA, and on my GM cars of the 80s-90s...
Posted by John Hopkins
- October 27, 2014, 07:01:50 AMThe wasted spark is not really wasted, it is to burn off any remaining fuel on the exhaust stroke..It makes the engine burn cleaner..or at least that is what some environmentalists would have us believe..
John.
Posted by Bucko
- October 27, 2014, 00:21:59 AMWhat's the advantage of a wasted spark system on a V twin? I guess it makes timing simple (no need to divide cranks rotations to time to the compression stroke - that could be easily done by the ECU), but is that the only reason? Makes all sorts of sense for a inline 4 - reduces the number of coils required by 2 but that doesn't apply to a v twin.
Posted by scamp62
- October 26, 2014, 20:47:20 PMThen is the Drifter considered a dual fire ignition ?
Posted by Troll
- October 26, 2014, 18:16:43 PMTapping both coils will likely keep the engine from starting at all, since each signal wire is actually the ground for the coil. Most tachs, at least they used to, have an adjustment on them for # of cylinders. When installing a tach on a Harley with single fire ignition, a special filter is required to get a reading from the coil. I'll bet that the waste spark system on an 800, using only 1 coil per cylinder, will signal on both the exhaust and power strokes, so there will be no issues with the tach reading 1/2 rpm...
Posted by scamp62
- October 26, 2014, 18:03:00 PMA little help from the brain trust out there please !
Installing an electronic tachometer on my 800. The question I have is there is a single engine signal line that is to go to the coil, is going to one coil going to give me a true reading, or should there be a line to both coils 
Any advice would be greatly appreciated.