anybody have a link to one? I want a multimeter and i would like to check what the idle is currently on my crf250. Figured i could kill 2 birds with one stone.
what do you guys have or used?
Multimeter w/ RPM for Single Cylinder?
Started by gaines1016, Nov 30 2009 03:27 PM
13 replies to this topic
Posted 30 November 2009 - 03:27 PM
anybody have a link to one? I want a multimeter and i would like to check what the idle is currently on my crf250. Figured i could kill 2 birds with one stone.
what do you guys have or used?
Posted 30 November 2009 - 06:30 PM
Don't think you'll be able to find a multimeter that does that. My Fluke 187 will measure frequency/period/duty cycle... with that you could interpolate engine RPM...
What I'd do.... get a current clamp and snap that around the ignition wire, then set it to read voltage frequency (pulses per second) and multiply by 60 to get pulses per minute. The current clamp will amplify the current through the clamp part into a voltage readable by the DMM.
600 RPM, one spark per revolution = 600 sparks per minute. Divide by 60 (60 seconds in a minute) = 10 sparks per second. Counting only rising edges, my meter would read 10Hz at a very low duty cycle.
I know ther'es not a whole lot of DMMs out there that read frequency (my fluke wasn't cheap, but I needed and use most of its features), so without some $$ and equipment I think you're SOL.
What I'd do.... get a current clamp and snap that around the ignition wire, then set it to read voltage frequency (pulses per second) and multiply by 60 to get pulses per minute. The current clamp will amplify the current through the clamp part into a voltage readable by the DMM.
600 RPM, one spark per revolution = 600 sparks per minute. Divide by 60 (60 seconds in a minute) = 10 sparks per second. Counting only rising edges, my meter would read 10Hz at a very low duty cycle.
I know ther'es not a whole lot of DMMs out there that read frequency (my fluke wasn't cheap, but I needed and use most of its features), so without some $$ and equipment I think you're SOL.
Posted 30 November 2009 - 06:55 PM
SnowMule said:
Don't think you'll be able to find a multimeter that does that. My Fluke 187 will measure frequency/period/duty cycle... with that you could interpolate engine RPM...
What I'd do.... get a current clamp and snap that around the ignition wire, then set it to read voltage frequency (pulses per second) and multiply by 60 to get pulses per minute. The current clamp will amplify the current through the clamp part into a voltage readable by the DMM.
600 RPM, one spark per revolution = 600 sparks per minute. Divide by 60 (60 seconds in a minute) = 10 sparks per second. Counting only rising edges, my meter would read 10Hz at a very low duty cycle.
I know ther'es not a whole lot of DMMs out there that read frequency (my fluke wasn't cheap, but I needed and use most of its features), so without some $$ and equipment I think you're SOL.
What I'd do.... get a current clamp and snap that around the ignition wire, then set it to read voltage frequency (pulses per second) and multiply by 60 to get pulses per minute. The current clamp will amplify the current through the clamp part into a voltage readable by the DMM.
600 RPM, one spark per revolution = 600 sparks per minute. Divide by 60 (60 seconds in a minute) = 10 sparks per second. Counting only rising edges, my meter would read 10Hz at a very low duty cycle.
I know ther'es not a whole lot of DMMs out there that read frequency (my fluke wasn't cheap, but I needed and use most of its features), so without some $$ and equipment I think you're SOL.
what are your thoughts on something like this:
http://www.sears.com...ters+%26+Meters
you are obviously schooled in the workings of multimeters. it says for 2 or 4 strokes from 1-8 cylinders but i never take the manf. word for those things. i am still a multimeter newb:thumbsup:
Posted 30 November 2009 - 07:00 PM
I have a hardline hour/tachometer and am greatly satisfied with it. It measures rpm in 10 rpm increments. Plus i opted for the mount kit that puts it where the front gas tank mount bolt is so its nice and easy to see.
Here's a link: http://www.motosport...re_val=dirtbike
Here's a link: http://www.motosport...re_val=dirtbike
Posted 30 November 2009 - 07:04 PM
Stihl and Echo -- the chain saw companys, make a small meter that is used to check RPM on 2 and 4 stroke engines . I bought one a few years ago for around $20.00 .
All you have to do is hold it up next to the plug cap!
All you have to do is hold it up next to the plug cap!
Posted 30 November 2009 - 07:11 PM
I bought this http://www.tinytach....ch/gasoline.php about 6 yrs ago and it works great (especially for the price). Now it's only a tach and not a DMM but it does what it's supposed to. :thumbsup:
Posted 30 November 2009 - 07:45 PM
TrailTech Vapor has a built in tach feature that works great for setting idle, plus a bar graph tach making it easy to see RPMs when riding.
Posted 30 November 2009 - 08:26 PM
There's quite a few that do this. Hardline, PC Racing, Moose, all sell one and I'm pretty sure they are all made by one company.
Posted 30 November 2009 - 11:14 PM
gaines1016 said:
what are your thoughts on something like this:
http://www.sears.com...ters+%26+Meters
you are obviously schooled in the workings of multimeters. it says for 2 or 4 strokes from 1-8 cylinders but i never take the manf. word for those things. i am still a multimeter newb:thumbsup:
http://www.sears.com...ters+%26+Meters
you are obviously schooled in the workings of multimeters. it says for 2 or 4 strokes from 1-8 cylinders but i never take the manf. word for those things. i am still a multimeter newb:thumbsup:
Features look nice, and it's obviously built to fill a niche market...
that being said, it's a 4k count meter. My Fluke, while it's on the high end of DMMs, is a 50k count.
The "count" is a measure of the resolution of the A/D converter. The measurement between the probes gets converted to a digital signal through the A/D converter. "One count" would return a binary number, 0 or 1. An "8-count" would be able to tell the difference between 8 levels. So you turn this 8-count meter on, set the range to 1 volt, and you can read 0, 0.125, 0.25...0.75, 0.875, or 1.0. The higher the count, the more resolution in the readings. And generally the wider the scales go. My old 4k count radio shack meter measured down to 100mV (0.1v) on its lowest scale; the 187 does 10µV (0.00001v). The frequency spec (20k) would have a resolution of 50Hz at 1MHz, or 20ms time.
I'm sure it's enough to do troubleshooting on vehicles, which is what it's built for, but $200 is more than I'd pay for a meter with those specs.
The temp thing looks like a pretty standard K-type thermocouple. Cheap and easy to find. If temp measurements are a big deal for you, get an IR thermometer. Don't have the settling time of a resistive thermocouple, the readings on IR are almost instantaneous. Thermocouples are great (cheap) for temperature control systems, since they will generally heat up as fast if not faster than the parts you're working with so settling time isn't a big source of error. When you want to get the temp off a radiator hose with a thermocouple, the method of coupling and the time the RTD's been on the hose will all contribute to the measurement error. With an IR thermometer, point the thing at the hose and pull the trigger... reading shows up on it in <1sec.
Not sure about the brand either, never heard of "universal enterprises". Might be big in the automotive world, but I've never heard of them.
I'm in test/electrical engineering which is why i'm so familiar with all this...
Posted 01 December 2009 - 06:22 AM
SnowMule said:
Features look nice, and it's obviously built to fill a niche market...
that being said, it's a 4k count meter. My Fluke, while it's on the high end of DMMs, is a 50k count.
The "count" is a measure of the resolution of the A/D converter. The measurement between the probes gets converted to a digital signal through the A/D converter. "One count" would return a binary number, 0 or 1. An "8-count" would be able to tell the difference between 8 levels. So you turn this 8-count meter on, set the range to 1 volt, and you can read 0, 0.125, 0.25...0.75, 0.875, or 1.0. The higher the count, the more resolution in the readings. And generally the wider the scales go. My old 4k count radio shack meter measured down to 100mV (0.1v) on its lowest scale; the 187 does 10µV (0.00001v). The frequency spec (20k) would have a resolution of 50Hz at 1MHz, or 20ms time.
I'm sure it's enough to do troubleshooting on vehicles, which is what it's built for, but $200 is more than I'd pay for a meter with those specs.
The temp thing looks like a pretty standard K-type thermocouple. Cheap and easy to find. If temp measurements are a big deal for you, get an IR thermometer. Don't have the settling time of a resistive thermocouple, the readings on IR are almost instantaneous. Thermocouples are great (cheap) for temperature control systems, since they will generally heat up as fast if not faster than the parts you're working with so settling time isn't a big source of error. When you want to get the temp off a radiator hose with a thermocouple, the method of coupling and the time the RTD's been on the hose will all contribute to the measurement error. With an IR thermometer, point the thing at the hose and pull the trigger... reading shows up on it in <1sec.
Not sure about the brand either, never heard of "universal enterprises". Might be big in the automotive world, but I've never heard of them.
I'm in test/electrical engineering which is why i'm so familiar with all this...
that being said, it's a 4k count meter. My Fluke, while it's on the high end of DMMs, is a 50k count.
The "count" is a measure of the resolution of the A/D converter. The measurement between the probes gets converted to a digital signal through the A/D converter. "One count" would return a binary number, 0 or 1. An "8-count" would be able to tell the difference between 8 levels. So you turn this 8-count meter on, set the range to 1 volt, and you can read 0, 0.125, 0.25...0.75, 0.875, or 1.0. The higher the count, the more resolution in the readings. And generally the wider the scales go. My old 4k count radio shack meter measured down to 100mV (0.1v) on its lowest scale; the 187 does 10µV (0.00001v). The frequency spec (20k) would have a resolution of 50Hz at 1MHz, or 20ms time.
I'm sure it's enough to do troubleshooting on vehicles, which is what it's built for, but $200 is more than I'd pay for a meter with those specs.
The temp thing looks like a pretty standard K-type thermocouple. Cheap and easy to find. If temp measurements are a big deal for you, get an IR thermometer. Don't have the settling time of a resistive thermocouple, the readings on IR are almost instantaneous. Thermocouples are great (cheap) for temperature control systems, since they will generally heat up as fast if not faster than the parts you're working with so settling time isn't a big source of error. When you want to get the temp off a radiator hose with a thermocouple, the method of coupling and the time the RTD's been on the hose will all contribute to the measurement error. With an IR thermometer, point the thing at the hose and pull the trigger... reading shows up on it in <1sec.
Not sure about the brand either, never heard of "universal enterprises". Might be big in the automotive world, but I've never heard of them.
I'm in test/electrical engineering which is why i'm so familiar with all this...
thank you very much for taking the time. i really do appreciate the info.
Posted 01 December 2009 - 10:19 AM
Measuring RPM for idle....I use me ear 'oles. If it idles good and it sounds right then it must be about right. Not sure that the actual figure matters. I set idle high, then adjust idle mix to get a nice round stable idle, then lower idle speed to where I want it to suit my riding.
Posted 01 December 2009 - 12:44 PM
Pedroski said:
Measuring RPM for idle....I use me ear 'oles. If it idles good and it sounds right then it must be about right. Not sure that the actual figure matters. I set idle high, then adjust idle mix to get a nice round stable idle, then lower idle speed to where I want it to suit my riding.
EFI bikes require 1800 to 2000 RPM idle.
