Tach not working

[rickardracing]

Ok, my gauges (Equus) all work. Finished the install, changed the oil and cranked her up. Oil pressure came right up, water temp took a few and finally came up to about 180 degrees. Volts, no problem. The tach is not working. The light works but the needle does nothing. So here's the poop. I need some suggestions.

The Tach is a Nitrous 2". I wired it as follows:

 

White: Night lamp...tapped into the driving lights.

Orange: Wired to the positive battery terminal.

Black: Chassis ground.

Green: To the negetavie lead on the coil. I am pretty sure it's the negative. According to the repair manual, it's the gray/orange (top terminal). My terminals are as follows. Red is the lower and white is the upper. So I connected it to the white terminal.

Red: Is supposed to go to the ignition switch accessory position. I just tapped into the lights again since they come on when the key is turned to the accessory position. This may have been my down fall. I am not sure where to tap into the ignition at. I am not sure if it makes a differance or not.

The tach does have a 4-6-8 cylinder switch. I tried all of these positions.

Tech support was nooooooo help.

Any ideas? I am bummed and pissed. I put alot of work into the tach housing. It really looks sweet, but it would look sweeter if the tach worked!

 

Randy

[dug050]

Hi Randy, there has been several threads on this site about connecting a car tach to the RSV. The problem is the RSV ignition system is not like a 4 cylinder car, it has 4 individual coils, one for each cylinder. If you just connect to one coil you should only read 1/4 of the actual RPMs but because the system is a wasted spark design (also fires the plug on the exhaust stroke) by hooking to one coil you will read 1/2 the actual RPMs. If you go to Tech Talk>General Tech Talk>Sun Super Tach II, there is a good thread where they work through this problem. You have to use an adapter.

It sounds to me that you have the wires hooked up properly and should at least be seeing a reading of 1/2 RPMs, if not you may have the green wire hooked to the positve post of the coil. I have a Royal Star which is not quite the same as your RSV and the negative post is on the bottom. I believe the bike shown in the post I mentioned is the same as yours and should resolve your problem.

 

Good luck, post some pictures.

 

Doug

[rickardracing]

Thanx Dug......I read the post, printed off the sketch and will do this this weekend. I will let you know what happens.

 

 

Randy

[donphantasmo]

Ok, my gauges (Equus) all work. Finished the install, changed the oil and cranked her up. Oil pressure came right up, water temp took a few and finally came up to about 180 degrees. Volts, no problem. The tach is not working. The light works but the needle does nothing. So here's the poop. I need some suggestions.

The Tach is a Nitrous 2". I wired it as follows:

 

White: Night lamp...tapped into the driving lights.

Orange: Wired to the positive battery terminal.

Black: Chassis ground.

Green: To the negetavie lead on the coil. I am pretty sure it's the negative. According to the repair manual, it's the gray/orange (top terminal). My terminals are as follows. Red is the lower and white is the upper. So I connected it to the white terminal.

Red: Is supposed to go to the ignition switch accessory position. I just tapped into the lights again since they come on when the key is turned to the accessory position. This may have been my down fall. I am not sure where to tap into the ignition at. I am not sure if it makes a differance or not.

The tach does have a 4-6-8 cylinder switch. I tried all of these positions.

Tech support was nooooooo help.

Any ideas? I am bummed and pissed. I put alot of work into the tach housing. It really looks sweet, but it would look sweeter if the tach worked!

 

Randy

 

Randy, I'm pretty sure that the green wire is supposed to connect to the positive of the ignition coil... The fact is.... A four cylinder is a four cylinder. If you will wire it to one of the ignition coils, it will pick up the charge from that cylinder (I think it is supposed to be the #1 Cylinder) and count it as a revelation. It will then see how many times it sparks in a minute, multiply it by 4 (for a 4 cylinder) and display it as such. It will also do the same for 6 or 8 cylinders accordingly.

Double check that green wire. I'm pretty sure it's supposed to go to a POSITIVE, not a negative...

 

Best of luck!!

[dug050]

Hi Randy, the post from donphantasmo is not accurate for the RSV because of the type of ignition they have. On cars with distributors and a single coil the tach was hooked to the negative post of the coil. The distributor fired the coil once for each cylinder and you set the switch on the back of your tach for the number of cylinders in your engine to get the correct reading. As you read in the post I referred to you, RSV ignitions do not work like this, stick with the procedure they gave and you will be successful. I'm sure others will confirm this. I have never seen a tach hooked to the positive side of a coil, all you have there is the 12 volts the battery supplies to the coils through the ignition switch.

 

Doug

[rickardracing]

dug050,

 

Once I read the post, it pretty much made sence. I am going to do this on saturday. I will post my results. Thanks to all who responded. Much appreciated.