Automotive style tach on the bike.....

[HiSPL]

Does any one use one? How does it work for you, and how does it hook up to compute RPM? Also what do you do with the factory tach sender on the valve cover? Does it need a cover or not?


I'm not worried so much about the mounting 'cause I will probably ditch my guage cluster soon. That leaves plenty of space for a big 'ol tach.....


P.S. What do you do about water? Are they waterproof/resistant?


TIA,
-=Tim=-

[lhanscom]

You should be able to get one that's waterproof, since some cars have them mounted on the hood. The big question though is, can you find an automotive tach that goes up to 10k rpm?

[Anonymous]

big question though is, can you find an automotive tach that goes up to 10k rpm?

Should be no problem. I looked for one for a project bike several years ago and could find ones for 10k and 12k (I think it was). They usually use an inductive lead that simply wraps around a spark plug wire to pick up the ignition pulses.

Mark

[Philly_Chris]

I thought the un-used spark was an issue. Basically you'd be reading at twice the RPM unless the tach accounts for this, which it may not if it is for a car...

Feel free to fill me in if I'm wrong

[KennyJ]

I think it will be tough to find one that is waterproof unless you look at the ones for marine applications. The big Autometers shed water OK, but are not waterproof (from having a tell tale tach in the stock car). You might be able to seal one up with some sealant and time.

As for hooking it up to a 4 cylinder bike with 2 coils, I think it will actually read slow. They usually can be set for 4/6/8 cylinders with 1 coil (thus 1 trigger). Your dual coils will trigger it as often, but it should think the 2nd trigger is cylinder 3.

I am sure it can be done, I have seen pictures of it. (like that means it works....)

Kenny

[Anonymous]

As for hooking it up to a 4 cylinder bike with 2 coils, I think it will actually read slow. They usually can be set for 4/6/8 cylinders with 1 coil (thus 1 trigger). Your dual coils will trigger it as often, but it should think the 2nd trigger is cylinder 3.

I was looking at them for a two stroke twin, so the firing thing worked out properly. It may give problems on a four stroke when reading from a plug wire. It would pay to read the directions carefully before throwing out the receipt...

Mark

[HiSPL]

Thanks for all the replies so far......

Thinking about it, if I set it to 8 cylinder operation, wouldn't it read correctly?

[Hap Call]

Thanks for all the replies so far......

Thinking about it, if I set it to 8 cylinder operation, wouldn't it read correctly?

Tim, that would be my guess.

Hap

[Flatline_Racing]

My guess would be that you set it for 4 cyl. because each coil fires once every revolution, there fore each sparkplug fires one every revolution of the motor.

[focus frenzy]

a normal inductive tach wont work, it looks for the single spark per cylinder you get with a distributer.
on a bike the tach would read 2X the crank speed.

I have seen a tach for cars with distributor-less ignitions, and one of those will work, as most distributorless ignitions use a single coil for two cylinders like our bikes.

[Anonymous]

Tach

Dont waste your money on a coventioanl tach get the digital with memory from dennis Kirk goes to 19,000rpm has a high rpm memory hooks into the cdi harness, is easy to read, at fast speeds and can be mount so your eye balls don't have to roam so far from the road, about $135, note will not work on points ign. or V-4s, I dont know about you guys but the needle type tach is to hard to read at 120plus, so I shift by the pull of the motor

[HiSPL]

Leds and lcds are really hard to read under the Texas sun.

[HiSPL]

Problem solved thanks to a little googlin'...... 8)

http://procycle.autometer.com/index.html

Found it here; http://www.motorcyclecruiser.com/acc...andgear/tachs/


Thanks all.....

[Hap Call]

My guess would be that you set it for 4 cyl. because each coil fires once every revolution, there fore each sparkplug fires one every revolution of the motor.

Automotive tachs fire off each time the spark plug fires which is once every two revolutions of the crank. A motorcycle's fire once every crank rotation, at least on our four cylinder bikes. If you set the automotive tach on for 4 cylinders on our bikes it would show twice the RPM...at least that's the way I understand it.

Hap
Been wrong in the past, will be wrong in the future.