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.

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

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.

Well, I finally got the time to work on my bike today and got the new tach mounted and all hooked up. It looks really nice but when I started the bike it registers low on RPMs no matter where I set it. Here is how I hooked it up. I ran the wires into the headlight housing to get 12 volt and ground. I ran a short jumper wire between the 12volt and light terminals on the back of the tach. I then ran the signal wire to the white wire on the coil that is up above the front of the engine on the right side of the bike. The only thing I am wondering about is whether or not I hooked the signal wire to the right place on the bike, any advice will be appreciated. Thanks again, Phertwo, for all the details you wrote up on this, it looks great and surely I will get it working correctly with some help.

I really like the way your tach looks and the way you mounted it on the bike. I hope you don't mind that I am going to copy your idea. I ordered my new tach and housing yesterday so I am excited to get started installing it in my warm shop since it is cold here. The way this tach matches the bike's gauge is what sold me, looks great at night too. I will post a picture when I get it installed. My bike is the one that Wedgebolt has pictured here, I bought it last spring on ebay, it has flames on it so it ought to have a tach. Thanks for all of your details on the install.