can i run a electric tack

[odl777]

will a eletric tack from a car work on a 79 gs 750? thanks

 

[Roadwarrior]

Your GS is an inline 4 with two coils. Unless its a 2 cylinder car, your RPM readings will be off.

 

[MrSector9]

It will work since ther eis a wasted spark on each cylinder.

Most modern 4 stroke cars are setup the same way. 2 coils wasted spark on each cylinder.

Also depends on if you buy a good tach or not. I knwo most autometer tachs will work. VDO tachs will also work.

I think however you have to set the cylinder number to 8 but cannot recall for sure. Also we put them on twin cylinder snowmobiles, even triples and they work on them too

 

[Guest]

Your GS is an inline 4 with two coils. Unless its a 2 cylinder car, your RPM readings will be off.

This is the correct response... I've done quite a bit of reading and this is the answer.

 

[MrSector9]

GM cars are setup the same was as motorcycles. 2 coils wasted spark on each like stated.There 6 cylinders are 3 coil packs with wasted spark.

I will go further into detail to explain this as I have done this before instead of read about it.

use any of the common boxes and it iwll work as they have signal output, dyna,msd,accell

When used with the coil most tachs are setup for single coil, if you hook up a single coil it iwll read half of the actual rpm, if you hook up both to it the bike will misfire. to solve this problem you use a diode (cheap at radioshack) between the 2 coils so it will allow the signal to be sent one way but not the other allowing the 2 coils not to bridge.

Autometer has a 2 coil adapter (contains said diodes formore money)

Soem automotive tachs are setup and have a switch for 2 cylinder operation.

 

[m in sc]

get a tach that can read a 2 cylinder, there are pleny of them out there on ebay for the blinged out fast and furious crowd that can be set to read 1,2,3,4,6,8 & 10 cylinder engines.
I had one on my liquid cooled rd i ran with wasted spark and it was dead accurate. Mine was an autometer gauge.
remember, a car ignition (standard) spins the distributor @ 1/2 the speed of the engine. So, for an automotive 4 cylinder, the crank spins 360 degrees, and the distributor spins 180 degrees, firing the coil (and tach) twice every 360 degrees of crank rotation. You need a setup that you can read 1 fire every 360 degrees of rotation, hence a 2-cyl setting is required.

heres the tach I had on my rd:

 

[odl777]

I let you guys knoe when iget the taq it has a shift light on it also will it still work. My buddy said he would give it to me for 10 bucks and it looks nice so why not try it. The taq is out of a s10 extreme pickup. thanks for the help.

 

[MrSector9]

the stock tach?

if it is aftermarket wiht a shift light it will sitll work.

if it is a factory installed tach if you cannot chang ethe settings then no it will not work.

 

[m in sc]

yeah, the tach listed above has ashift light and annoyingly came on at 10k constantly :-D

 

[earlfor]

What rating diode is required?

Earl

When used with the coil most tachs are setup for single coil, if you hook up a single coil it iwll read half of the actual rpm, if you hook up both to it the bike will misfire. to solve this problem you use a diode (cheap at radioshack) between the 2 coils so it will allow the signal to be sent one way but not the other allowing the 2 coils not to bridge.

 

[hungryman]

The biggest problem using a car tach is that they are not waterproof.