tach replacement

[Broom]

i don't know much about how the tach and stuff works, but if i go down to the mc junkyard and pick up a little analog tach and wire it up to the stock wiring, will it work?

i also need a temp gauge. if i remember right the new 250 only has a dummy light, so i'll probably just wire up an aftermarket temp gauge myself and skip the stock wiring altogether.

any suggestions on how to get these two jobs done cheaply?

[randomwalk101]

where's your stock ones? let us know if it'd work or not...should cost too much doing it that way i think.

[Broom]

sold the stock dash... good place to make some cash!

[ztrack157]

Broom I picked up a Faze temp gauge off ebay for like $11. It works great wiring is fairly simple as well.

[HKr1]

Originally Posted by Broom

i don't know much about how the tach and stuff works, but if i go down to the mc junkyard and pick up a little analog tach and wire it up to the stock wiring, will it work?

Tach gets its signal from one of the igntion coils. Long as the bike you get the new tach from is wired the same, using the same type signal. Should work............

GL

[Banzai]

Just make sure whatever tach you use is for, or can be set up for, a 2 cylinder. For most aftermarket tachs, that means either cutting some wires inside or on the back of the tach, or setting jumper pins. Stock tach takes a feed from the CDI/coil BLACK wire, but the GREEN wire to the other coil will work as well.

[HKr1]

Originally Posted by Banzai

Just make sure whatever tach you use is for, or can be set up for, a 2 cylinder. For most aftermarket tachs, that means either cutting some wires inside or on the back of the tach, or setting jumper pins..

Wouldnt that be a 1 cylinder? Your only getting a signal from one of the two coils. If there was one coil getting fired twice, for cyl's 1 & 2..... wouldnt that be a setting for a twin

What do you think?

[Banzai]

Originally Posted by HKr1

Wouldnt that be a 1 cylinder? Your only getting a signal from one of the two coils. If there was one coil getting fired twice, for cyl's 1 & 2..... wouldnt that be a setting for a twin

What do you think?

Nope! He needs a motorcycle specific product.

Each cylinder fires only ONE time for each revolution of the crank (which is what the tach is keeping track of), so you only need one timing reference. The internal workings of the tach keep track of everything else. Since we have two coils, each has a trigger wire coming from the CDI, and fires only one time per revolution. Thus, you only need a sense from either, but NOT both.

If you were to take two signals and route them to the tach, it would double count, and you'd get TWICE the RPMs indicated that the engine was actually turning.

Most tachs have only 4 wires. 1 power +, 1 ground, 1 backlighting power +, 1 RPM coil sense. Aftermarket tachs usually either have a series of wires that you cut to set the cylinder count, or jumper plugs that you have to put in place.

For cars, they pretty much come standard set up as 8 cylinder and assume ONE coil, in which case for each 8 triggers counted, it indicates ONE RPM. If the car has multiple coils (like one coil for every two cylinders or one for each), you have to either compensate with your set up or get a different tach). For motorcycles, they usually come set up for 4 cylinders, and you adjust them from there.

[HKr1]

Originally Posted by Banzai

Nope! He needs a motorcycle specific product.

Each cylinder fires only ONE time for each revolution of the crank (which is what the tach is keeping track of), so you only need one timing reference. The internal workings of the tach keep track of everything else. Since we have two coils, each has a trigger wire coming from the CDI, and fires only one time per revolution. Thus, you only need a sense from either, but NOT both.

That was my question to you You first mentioned needing a tach for a twin(two pulse). Being 250r is using two coils, thats 1 pulse each... Like a 1 clyinder tach

Guess were all on the same page now

[Banzai]