A 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.
Tapping 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...
Then is the Drifter considered a dual fire ignition ?
What'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.
The 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.
Waste 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...
One 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 ?!?
the tach signal is low voltage...actually a pulsed ground, so no, not the high tension side.
So were do you make the connection ?
and thank you for the help !!
I 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.
O.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 !!
B+ 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.
Troll your my hero !!! that all makes since !!!....thank you sir !!!
please let us know how it works...I'm sure everybody is interested.
Will do !!!
Well after 2 hours of fiddling, and the good words of wisdom from the Troll we have success ! My Drifter has a tach, !! Really the only tricky part was how do you tap-off the coil. Just not a lot of wire to work with, so I made an extension between the coil, and the lead, with a tap off it. All works well. Again thank you Troll
Scott
Glad to hear it works. Which wire did you use? Green or black and white?
Pictures, you know, we need PICTURES!!! ;D
I'd like to see it mounted, too.
Black & white wire
That's a good look, Scamp.
Is that a DS? Haven't seen any with a white face before. What color is the back light?
The tach, make is KEGE, the back light is white for the first 8k then from 8k to 13k is red
Well now you can perovide us with some info, if you have not done the sprocket swap, you can see what your rpms are in different gears, then do the sprocket swaps and see the difference........lol......
scamp62: Nice install. Assume you have stock sprockets. If so, I am also interested in actual readings in each gear at normal shifting points usually determined only by sound....for instance:
1st to 2nd @ 20mph
2nd to 3rd @ 30 mph
3rd to 4th @ 40 mph
4th to 5th @ 50 mph
then rpm @ 60 mph
I know, I know....I drive like a senior citizen! (even got the senior discount on coffee at dunkin donuts recently without asking...I'm under 60)...but I tried the shift points in the owner's manual once and those are just crazy, but shows the engine is designed to be wound out more that I usually do.
So, just looking for some real data without doing all the math. Not convinced on the sprocket swap. Thanks if you can oblige.
I wish I had thought about the tach, after I bought the bike.
KW, I was leey about the sprocket swap at first, and I did the reading, and the belt set up did all the reading and learning, then GB got to me and I did the swap only on the front over the winter, Now not having a tach I had to go by ear sound alone. I used the ride to my sisters as it covers the spectrum of speeds from in town to small towns and open highways to major highways, and a lot of nice back quiet roads. I found a huge difference in just the front sprocket swap, only once did I look for a next gear. I then did the rear the following winter, and it was even better, and at a cost of less then $100.00 for the sprockets, I did the work myself, so I think it was weel worth the funds. As for around town, really nothing has changed, I can still pull away fast and as quick as the big boys do, so I will advocate the sperocket swap.
I'll say it again...
The sprocket swap is the #1 upgrade on the 800.
#2 is the progressive springs in the forks. Close second.
progressive 1500 springs of course......
ok got both done....I am good.......
sorry gents, I have an 18 tooth sprocket installed on my bike
ok one step ahead of the game already.......lol....
Foiled again....on data that is. Thanks.
P.S. I do love the 18 tooth sprocket !!!