Retro Tachometer - A different approach

[V7Goose]

I do not know what tach you have, so I can only tell you about the engine. A coil on the RSV or RSTD fires one time for each revolution (this is the same as a two-cylinder engine with only one coil). For a tach to register the correct RPM, it must be made for a twin cylinder engine or have a 2 cylinder setting. If you have a tach that can only be set to four or more cylinders, then you will need a "single fire adapter" that will allow you to connect it to two coils at the same time for it to work correctly in the 4-cyl position.

Goose

[Condor]

I do not know what tach you have, so I can only tell you about the engine. A coil on the RSV or RSTD fires one time for each revolution (this is the same as a two-cylinder engine with only one coil). For a tach to register the correct RPM, it must be made for a twin cylinder engine or have a 2 cylinder setting. If you have a tach that can only be set to four or more cylinders, then you will need a "single fire adapter" that will allow you to connect it to two coils at the same time for it to work correctly in the 4-cyl position.

Goose

 

Just what I was about to ask. I set an Autometer Pro-Cycle tach to the Harley setting and wondered if it was right for the '99RSV?? I haven't installed it yet, so I wasn't sure if it was right or not. Also wasn't sure what Goose had posted previously, but I guess I remembered right.

[DarrinGT]

According to the research that I have done, When installing an automotive tac you need to wire it like this. It was posted in the original post.

 

http://www.gadgetjq.com/tach_install.htm

 

Please correct me if I am wrong, since I will be doing mine this week,...

[V7Goose]

According to the research that I have done, When installing an automotive tac you need to wire it like this. It was posted in the original post.

 

http://www.gadgetjq.com/tach_install.htm

 

Please correct me if I am wrong, since I will be doing mine this week,...

That information is meaningless without specifying both the tach to be used and the exact vehicle ignition system to which it will be connected. As it applies to an RSV/RSTD, it is ONLY correct if you have a tach for a four cylinder, single coil ignition.

 

Tachs are made in lots of different configurations, so it is a little difficult to try and give connection details for just a generic tach and expect it will work for all bikes and all tachs. But here is a basic overview (again):

 

Our bikes have four coils, but each fires one time in every revolution of the engine (just like a stock HD with dual-fire ignition). So any tach that will work on a stock HD motorcycle will work fine for us when connected to just one coil.

 

A tach that is for a standard 4-cylinder engine with a single coil and distributor will only work on our bike if it is connected to two coils with a single-fire adaptor.

 

A tach with a setting for "12 pole alternator" (or something similar) is intended primarily for outboard motors or diesel engines where the signal is an AC feed from the alternator; it needs six pulses per revolution and will not work properly on this engine in that setting.

 

One last comment for DarrinGT - I note that you have a 97 Royal Star, not a post '99 RSV or RSTD. I personally have no idea how many coils your engine uses, or what type of ignitor it may have, so you should make sure to understand that before you hook it up like we say for the current 2nd gen engines.

Goose

[Condor]

A tach with a setting for "12 pole alternator" (or something similar) is intended primarily for outboard motors or diesel engines where the signal is an AC feed from the alternator; it needs six pulses per revolution and will not work properly on this engine in that setting.

 

Goose

 

A little more info on a Marine Diesel tach. The last Teleflex I installed on a Yanmar Diesel Outboard had a magnetic pick up that read off the number of teeth on the flywheel.

[DarrinGT]

That information is meaningless without specifying both the tach to be used and the exact vehicle ignition system to which it will be connected. As it applies to an RSV/RSTD, it is ONLY correct if you have a tach for a four cylinder, single coil ignition.

 

Since this thread is about installing an automotive tac on a Royal, and knowing that An automotive tac is a single coil ignition, and they have a setting for 4cyl motors, makes this information is not meaningless. As I stated before, it was in the original post so I reposed it.

 

My 97 Royal has 4 coils like the Ventures, so I will be wiring it up in the same manner.

 

Here is another thread regarding an automotive tac, showing the same wiring diagram in the last post.

 

http://www.venturerider.org/forum/showthread.php?t=52293&highlight=automotive

 

 

Here is a quote from that post:

 

I'm not familiar with autometer tachs but I did install an automotive tach on my 96 Royal Star by setting the tach on the 4 cylinder setting and connecting to two coils. To do this you have to build a simple adapter to read the pulses from the two coils. Because the coil fires twice per engine revolution, by hooking to two coils you get four pulses which should give you the proper readings on your tach set for a 4 cylinder. I can't guarantee that this will work with all brands of tachs but it worked well for me.

Good luck

Doug

Here is the PDF on the wiring.

[1joeranger]

I really like this website: http://www.classicinstruments.com/ that phertwo has found for us and am trying to figure out how to install one of the instrument panels pictured below into the RSTD! Gonna be thinking about that for awhile!!!

[V7Goose]

Since this thread is about installing an automotive tac on a Royal, and knowing that An automotive tac is a single coil ignition, and they have a setting for 4cyl motors, makes this information is not meaningless. As I stated before, it was in the original post so I reposed it.

 

My 97 Royal has 4 coils like the Ventures, so I will be wiring it up in the same manner.

 

Here is another thread regarding an automotive tac, showing the same wiring diagram in the last post.

 

http://www.venturerider.org/forum/showthread.php?t=52293&highlight=automotive

 

 

Here is a quote from that post:

 

Here is the PDF on the wiring.

Sir, you seem to have taken some sort of exception to my response to your post. I am sorry if I have upset you in some way - I was actually trying to help you (and you did specifically ask for that help).

 

You did not specify what kind of tach you were using. All automotive tachs do NOT have setting for 4-cylinders. Many automotive tachs these days are designed for electronic ignitions with dedicated tach connections or for the fairly common multi-coil engines. In addition, many tachs use alternator pules or magnetic pickups. And lets not forget those tachs that are designed to use a simple inductive pickup like Koso. The days when everything was designed for a single coil and distributor are long gone. Furthermore, the OP said he used the "12PALT" setting on his tach, and that cannot work properly on this engine when triggered from one coil. So on the chance you were using the same tach, I did not want you to make the same mistake.

 

And just for clarity, the information you just quoted from "Doug" is quite wrong, even though he did connect his tach correctly.

 

Here is the quote you used:

"I'm not familiar with autometer tachs but I did install an automotive tach on my 96 Royal Star by setting the tach on the 4 cylinder setting and connecting to two coils. To do this you have to build a simple adapter to read the pulses from the two coils.

Because the coil fires twice per engine revolution,

by hooking to two coils you get four pulses

which should give you the proper readings on your tach set for a 4 cylinder

. I can't guarantee that this will work with all brands of tachs but it worked well for me.

Good luck

Doug"

I have highlighted three things that are quite wrong in that quote. First, the coils on this bike fire once for every revolution, not twice, thus you get two pulses per revolution if you connect two of them together through an isolation diode. And a four cylinder, four cycle engine will fire two times on every revolution, so two pulses is the correct number for a 4 cylinder tach.

 

BTW - Smely's post in that other thread was much more useful (but only if you know the correct number of pulses per revolution you get on this bike), whereas the response from Autometer that Sideoftheroad posted just showed that they did not understand motorcycles.

 

I wish you the best of luck in setting you your new tach,

Goose

Edited January 31, 2011 by V7Goose

[Woodman]

OK, here goes, I have installed my new (automotive) Classic Instruments tach just like the one phertwo used at the top of this thread. When I hooked it up the only setting that even begins to work is with the tach set for 4 cylinders and at that setting it is showing half the RPM. With some thought process going on in my head I figured that a four cylinder car engine is going to fire two times per revolution and I am only getting one time per rev. by hooking up to one coil on my bike, so this all makes sense to me. The answer in my mind was to hook up to two coils to double the number of signals per rev. I went to radio shack and purchased the 1N4007 diodes and the 100Kohm resistors and made the Y connection as described earlier in this thread. I hooked up two coils with this setup and the tach shows almost no RPM at idle and when reving the engine it does come up but not correctly. I took the shrink tubing back off my Y to make sure I had the diodes wired correctly and they are with the silver ring closer to the tach than the coils. I had the tach hooked up to #3 and #4 cylinders and got to thinking that maybe they were firing at the same time because of the firing order with one of them on the wasted spark while the other is actually firing. I switched to #1 and #4 with no change. Now I am wondering if the Y connecter I made will actually work on this bike, has anyone used this setup. My next question is if it is the same thing as what Barons includes with their tachs for single fire ignition bikes. I would try the Barons adapter but if it is the same as what I made I hate to waste my money. Any suggestions would be appreciated.

[V7Goose]

Looks to me like the diodes are backwards. The cathode (band) needs to point towards the coils.

 

It makes absolutely no difference which two coils you use, but why in the world would you chose one rear coil and one front one??? It only makes sense to me to use two coils close to each other (#2/#4 under the tank or #1/#3 under the swing arm)

Goose

[Woodman]

The diagram clearly shows the diodes installed the way I have them but just to be sure I did try to reverse them already and got no signal to the tach at all. The reason I used one of the back coils is because the #2 cylinder coil up front is really buried behind the radiator and hard to get to. Classic Instruments tech support told me I could get a part from Dakota Digital (SGI8) that will adjust the spark however I need it but it is another $75 and I'm not sure it will work. I just don't want to get too much invested and still not have something that works. Thanks for your thoughts

[DarrinGT]

Sir, you seem to have taken some sort of exception to my response to your post. I am sorry if I have upset you in some way - I was actually trying to help you (and you did specifically ask for that help).

 

No Problem Goose, thanks for your input!

[Woodman]

I have now completed the installation of my Classic Instruments Tach like the one at the top of this thread. Here is what I had to do to get it to work correctly. I mounted it almost the same way as the tach at the top of this thread. I went to Walmart and bought a stainless steel ladle for $5.50, removed the ladle part and bent the handle to fit the bike as described by pertwo earlier, cut down the chrome tach cup by 5/8 inch to clear the windshield then welded them together with stainless wire in my mig welder. I practiced a little on the ladle and the part of the cup that I cut off just to make sure I had my welder set correctly, it worked great. Instead of using silicone between the ladle handle and speedometer housing I used a strip of velcro about 2 inches long right under the tach, it works great and doesn't show unless you really look close. Got it all mounted and hooked up and it showed half RPM with the setting on 4 cylinder. Here is how I had it hooked up. Power and ground from the headlight housing, that way the wires don't constantly flex, the tach signal wire went to the white wire on the coil for #4 cylinder (front, right cylinder). Phertwo stated that he has his tach set on 12palt and mine didn't work on that setting so I tried the other settings and 4 cylinder is the closest at half RPM which makes perfect sense if you consider how our bikes fire. That is when I made the adapter that is described toward the top of this thread where it says (build). It is designed to hook two coils to the tach to double the signal without allowing the coils to enteract with each other. In my earlier post you can see that I couldn't get that to work on this bike. This is when I called Classic Instruments for help and he told me to buy a (SGI8) from Dakota Digital. I called them and they assured me that it would work but that it is not waterproof. I bought one on ebay for $75 and it works great. Here is how the tach is now hooked up. Tach power and ground still in headlight housing, power to the SGI8 is from the red w/black stripe wire on the coil, tach input on the SGI8 is hooked to the white coil wire, output 2 on the SGI8 is hooked to the tach signal, ground on the SGI8 is hooked to a bolt under the tank. Now for the settings on the SGI8. Switches 3&4 are both off ( that is for a 4 cylinder tach setting (the tach is still set for 4 cylinders) there is a little green light that flashes to set the SGI8 for engine cylinders, you want it set for 2 cylinders and then it works great. I hope this helps anybody that tries to use this tach or probably any other automotive tach. The cost did get up to real close to $300 but what the heck, it looks really nice.