Inductive RPM multimeter

To fine-tune my idle as well as get some misc tools consolidated, I had been looking at the ESI-585K Automotive Multimeter . Upon asking if this would work with 4- and 2- cylinder motorcycles, they replied that it wouldnt and suggested the ESI-321 Digital Tachometer ... which is twice the cost.

My question is... if my motorcycle is a 4-cylinder and many cars are 4-cylinder, why wouldnt the required tach be the same?

Thanks to anyone who can help me with this question!! (Somehow I think good ole' WiredGeorge coming in to drop knowledge...)

Cheers,
Dustin

Post edited by: eMusicMan, at: 2007/07/15 13:50

on a car, at least one with a distributor you get one igition pulse per cylinder per 2 revolutions. on our bikes you get two so an automotive tach will show you twice the actual rpm.
Ride safe

The Milkman wrote:

on a car, at least one with a distributor you get one igition pulse per cylinder per 2 revolutions. on our bikes you get two so an automotive tach will show you twice the actual rpm.
Ride safe

Woah - so the guy was telling me the truth? Honestly I was getting the feeling that he simply wanted to get me into the much high price-point (and single-tasking) product!

Would the Automotive Tach still be viable and just know that I need to divide the readout amount by two? Or is it more complex than than when I start looking at 2-cylinder engines, etc?

Thanks a lot!!
-Dustin

PS - Would you mind sharing why this difference happens in cars and bikes? (if you have the time and are so inclined to teach a newbie)

RPM: 2/DIS 0-3200 RPM, 6,000 RPM x 10

The above statement (copied from the linked site) says it will work with a four cylinder KZ.

The KZ four ignition is a DIS style (I think DIS is a trademark of the Ford Motor Co.)

Distributorless Ignition System

The KZ twins are just half a KZ four, ignition wise, and since the inductive pick up fits on a spark plug wire, and since it's going to see one spark event per revolution on both a four and a twin, then I'd say it's not going to know the difference between a four and a twin.

Post edited by: steell, at: 2007/07/15 20:18

Since I was called on to provide an answer, got to say I am not sure. I suspect the folks told you the truth... The Kaw ignition is called a "LOST SPARK" ignition or something along those lines. There is spark TWICE for every ignition cycle. The one time the ignition sparks, the valves are not in a position where the spark ignites the mixture. That is why you have to turn the crank around twice to find the actual TDC. In any case, this would bugger a tach. Folks that run an inductive tach (not a shop tach but a handlebar tach) with twin coils have to add a resistor based device to connect the coils in some fashion so the tach will work. I used to have a link to the tech details if you are interested but suggest this might need to be done to get this tach to work. Again, I am waddling around outside direct experience and sort of talking about a subject I have only "heard" about and not actually done. BTW: If you want to set your idle, just do it by ear. Most of the Kaw tachs are too inaccurate at the lower rpm range to be of much use. On one bike, the correct idle will be around 1500 rpm and the next, it will be 1100 rpm... the first bike obviously has the tach reading a bit too high. They seem to be more accurate up where the bike is actually being operated on the street.

wiredgeorge / steell / milkman - I have to say, y'all kick some major arse. Thanks for sharing your knowledge with me on this whole topic...

Sounds like the 585K would work in my case, but only by sheer luck lol. I think I'll pass on it and see if I ever find a multimeter which would be better suited to working on other bikes too.

Thanks again everyone...

-Dustin

Dustin, A precision multimeter is a must for every professional electrical engineer and designer! Fortunately, you ain't either so can get away with an el-cheapo multimeter from Harbor Freight. Since I tend to break meters, it is a good thing the one I use is only $2.98 on sale... I generally buy 3 or 4 of them at a time as it is cheaper to replace the meter than the batteries they come with bwhahahaha... these meters are not real accurate but good enough for bike work.

The cheaper ones work, but just require some math to be accurate. Same goes for timing lights with advance-knobs. Same goes for electronic dwell meters. Same goes for electronic car tachs.

As side note, for you twins guys, some things, like the car tach will work on twins without a multiplication problem. You set it to 4-cylinder mode, then it works right. A 360-degree twin's coil fires like a 4-cylinder-distributor car's coil... twice per crank revolution.

Wasted spark like the KZ's use has been used on automobiles for at least the last 17 years, and probably longer, and any tach made for a four cylinder car with wasted spark (and there are a lot of four cylinder cars with wasted spark ignition) is not going to know the difference between a car and a KZ four.

Four cylinder cars with 2 coils, six cylinder with three coils, etc

The problem is that most of the cheap aftermarket car tachs are all for 25 year-old cars and older. And who's going to get an expensive one? :laugh:

After thinking I would not hear back from them, I had started this post... but finally I heard back directly from ESI ... and here's what they had to say:

As far as the 585K RPM working on motorcycles it would be 50/50. That goes
for our DMM's as well as all other brands, including Fluke brand. The
reason - these DMM's are all designed for the autmotive market, by far the
largest buyer of these items.

Why don't they work on motorcycles very well? DMM's can not filter the high
amount of EMI noise produced by the CD ignitions on your motorcycles,
outboards, snowmobiles, etc..., basically all small engines use CD ignition.
Automotive ignitions are much "cleaner" from this stand point, and do not
require filtering of the RPM signals.

We do build a tachometer that will work on your motorcycles. It is our #321
Versa Tach. This model is built with much more robust circuitry and we
spray the inside of the case with EMI shielding.

I hope this helps you, please let me know if you have any questions.

Regards,

Steve White
ESI

I think this was great of them to reply and try to explain... anyhow, just sharing...

-Dustin

Post edited by: eMusicMan, at: 2007/07/17 10:55

yeah, nice. I don't believe they are trying to up-sell ya. They are trying to look out for you, but their explanation does not apply to KZ's. KZ's don't use CDI, (even though many industry people seem to think so).