RPM meter

[Sutty 96]

Hi Guys

 

Forgive the low level and ignorance of this question, but I'd like to be certain about what I'm doing, and I've tried my best to understand, from my limited knowledge. I have a quad bike, which I want to set the RPM for, for an electrical test, as it happens. It's a single cylinder 4 stroke, and is many miles away, so I'd like to set-up what I need before I go. To this end I've purchased a small, cheap, induction RPM meter. I doubt they're super accurate, but it should be good enough for my purposes. I bought the meter for both setting the revs on this quad, but also for all my other small engine equipment, including my Wheel Horse.

 

In order to test the RPM meter, and make sure I was setting it correctly, I decided to use my Wheel Horse, which has a 14hp K321 Kohler engine. This will be single cylinder and 4 stroke too, I suppose, and I thought it would be a simple matter of reading the instructions, setting the engine type, wrapping the wire around the HT lead, and off we go. Sadly the instructions are awful. They do however have what I think are useful codes to help, but it's the description of each that is so dreadful.

 

Code 01  2P1R

Code 02  1P1R

Code 03  1P2R

Code 04  No rpm

Code 05  Reset

 

I didn't work out what these meant until I went to look at an online video, for a similar type, a better one, that actually had a decent description of the engine after the code, in their manual, and as he read the descriptions from his, showing the page, I paused the video and looked at their codes. These said, 1P2R, 4 stroke, single cylinder, 1 spark, 2 revolutions. Perfect, I thought, with the P, perhaps, just referring to pulse, as opposed to spark, and the R to revolutions, as the better product described their code? Despite the horrible description in my manual, complete garbage, do you think it is safe to assume that they got the codes right in my manual too, thus I can assume that the 1P2R setting is what I'm after? I hoping those of you with more familiarity of such products, might be able to confirm. I'm thinking I'm right, but would like to be certain.

 

I have tested it on code 3, and get 800 RPM at idle on my Kohler. In addition, I counted the RPM by hand, audibly, 1,2,3,4,5,6,7,8,9,10 put up finger, repeat, put up another finger, until 10 fingers, then repeated, until I had 20 sets of 10. I can just count fast enough, for this. This took 31 seconds, on my stop watch. What I think I was listening to was the exhaust puff, of an engine running too slowly at idle, again another reason for getting this meter. Very roughly, call this 30 seconds, so I would have had 400 puffs in a minute, which I am thinking will be 800 RPM?

 

Is my counting method right, for reading the low revving of the idle on my Kohler, because if so, that does stack up with the 1P2R setting and the reading I got with the meter of 800 RPM?

 

And, whilst I'm here, what's the correct idle speed for a 45 year old 14hp Kohler K321S, because I've always thought it too low, despite the fact that it will happily sit there, idling like that, for as long as I leave it? The very fact that I can count it, always made me think it was too slow. Is too slow detrimental, if it keeps going, which it does?

P.S. A quick search here, before posting, looks like it should be 1200? With 800 being way too low, as it can impact "splash lubrication", or so I just read. I'd better fix that. Glad I got this meter, if I've set it up right?

 

Thanks ever so much in advance for any guidance.

 

Best regards

 

Sutty

Edited February 24, 2023 by Sutty

[RED-Z06 2,221]

1 spark 2 rev on K series.  

Magnums would  be 1 spark 1 revolution 

[RED-Z06 2,221]

The factor is what drives the spark...if its cam driven, such as a kohler points engine it sparks every other crank revolution.  If its crank driven such as with a solid state coil, you get a spark every revolution and 1 is wasted. So the tach reads every spark and knows time, so it needs to know if the number of sparks its seeing is 1/2 the crank speed or 1/1 the crank speed.

 

I use a cheap laser tach..you put reflective tape on anything that spins and point it at it..gives you rpms...which is nice because i can check speeds of things independently of ignition 

 

 

[ri702bill 8,318]

9 minutes ago, RED-Z06 said:

you put reflective tape on anything that spins and point it at it..gives you rpms

My HF non-contact Tachometer works fine - but not in direct sunlight.

[Sutty 96]

Nice one RED-Z06, thanks, so I was right with the Kohler, but that may not be right for the quad bike. I'll see what I can find out about that engine. Funnily enough, as I'd been pondering this stuff, it crossed my mind that perhaps some designs might just waste sparks, and then I thought, no, don't be silly, why would they do that, lol.

 

Thanks very much for the explanation.

 

When looking at what to buy, I considered a laser type, but then thought, there's nothing I can see that's spinning on the Quad, and I'm not sure I can open anything up whilst running, especially not in a shed, miles away from home, to allow it.

Edited February 24, 2023 by Sutty

[RED-Z06 2,221]

14 minutes ago, ri702bill said:

My HF non-contact Tachometer works fine - but not in direct sunlight.

Ill have to remember that.  I got so tired if the erratic inductive pickup tachs, it was nice to get one i trust.

 

The inductive ones you really have to spend some money to get one that works and they can be fragile sometimes 

[Sutty 96]

By the way, I have an optical tach for my hobby of flying RC model helicopters, for rotor RPM. Could I put white tape on the spinning cage, on the side of the engine, and tach that, with my optical tach, by way of further confirmation, or is there already some ratio in play there? I don't think there is, and I'm guessing that would be okay, as long as I set it to single blade.

[squonk 41,097]

I use my photo tach by putting the tape on the crank pulley. Of course you have to remove the PTO pulley to do it but it's no big deal.

[Sutty 96]

So, I just drop off the PTO clutch part, to reveal the flat plate behind? I've just been to look at that, and it appears, at first glance, to be just a few R pins, and one circlip in the middle, on the shaft, which if so, easy enough, as you said.

 

Again, at a glance, it looks as though I could just put a bit of tippex on the edge of the plate behind, and see that well enough? I'll take a look tomorrow, because my optical tach doesn't work in the dark, and it can't be trusted under the flickering of mains lights.

Thanks for that.

Edited February 24, 2023 by Sutty

[RED-Z06 2,221]

51 minutes ago, Sutty said:

By the way, I have an optical tach for my hobby of flying RC model helicopters, for rotor RPM. Could I put white tape on the spinning cage, on the side of the engine, and tach that, with my optical tach, by way of further confirmation, or is there already some ratio in play there? I don't think there is, and I'm guessing that would be okay, as long as I set it to single blade.

I stuck mine to the steel screen over the flywheel 

[Sutty 96]

I think that's what I was trying to describe by saying cage. The part you can see in the picture for your avatar? If that's it, then it has to be easier than any disassembly, regardless of how straightforward that might be.

[Racinbob 11,070]

No need to disassemble anything. Just stick a piece of the reflective stuff on the flywheel screen like I did here. 

 

 

 

[Sutty 96]

Thanks, I'll do that, after lunch, I've been busy this morning. That's what I thought people were meaning, but a picture's worth a thousand words, so thanks again. I think your horse looks lovely by the way. Makes me think mine needs at least a wash, lol.

 

Not sure how to work out what's going on with my quad engine, in terms of sparks per cycle, but I'm going to leave my meter set-up as it is, and measure it, when I can get back up there to where the quad is located, and see what answer I get. Once I have the optical tach check on the horse, I'll know for sure that I've set the inductive tach correctly. I can then also set the idle correctly on the horse, nice and easily with the optical tach, once I've found the manual for that tach, lol.

 

Finally found the confirming data that the low speed idle should be 1200 rpm, for my K321S. It's right there in the engine manual, but my manual, although a pdf, is just based on a scan of the original document, so it isn't searchable for text. Always very frustrating. I hope I haven't done any harm with the low idle being at 800 for so long. Fingers crossed all is well. It won't have spent a whole deal of time at idle, in the grand scheme of things, because it doesn't really get used that much, at least not relatively speaking. More like monthly use, as opposed to a daily runner, and mostly it would actually have be running at mid revs, not idle.

Whilst I'm here, is there a proper K series Kohler engine manual available, such that it has clickable links and searchable text and not just a scan?

[Racinbob 11,070]

That tractor is definitely my baby. I purchased it brand new. 

I wouldn't worry about harming your engine at low RPM. Even at 800 rpm there a lot of splishing and splashing going on to protect the engine. As a kid my Dad would pull us kids, big and little, around the property on a trailer with the engine at idle or just cracked above. It was like a game to him seeing how much he could pull up hills before the engine stalled. An engine was never hurt. I run all mine at whatever rpm that suits me at the time. Of course it will tell you to go max when running pto driven attachments. Except a sickle bar mower. It will QUICKLY tell you not to run it that fast. 

[Blasterdad 2,692]

25 minutes ago, Sutty said:

is there a proper K series Kohler engine manual available, such that it has clickable links and searchable text and not just a scan?

 

[Sutty 96]

That's perfect, thank you. I typed in the search, rpm, found 8 hits, the very first of which directly followed the numbers 1200. 

[Sutty 96]

39 minutes ago, Racinbob said:

That tractor is definitely my baby. I purchased it brand new. 

I wouldn't worry about harming your engine at low RPM. Even at 800 rpm there a lot of splishing and splashing going on to protect the engine. As a kid my Dad would pull us kids, big and little, around the property on a trailer with the engine at idle or just cracked above. It was like a game to him seeing how much he could pull up hills before the engine stalled. An engine was never hurt. I run all mine at whatever rpm that suits me at the time. Of course it will tell you to go max when running pto driven attachments. Except a sickle bar mower. It will QUICKLY tell you not to run it that fast. 

 

Good to know that it's unlikely to have caused any damage. Right's right though, so I'm off to set it now.

 

Thanks all.

 

Sutty

[tunahead72 2,412]

45 minutes ago, Sutty said:

That's perfect, thank you. I typed in the search, rpm, found 8 hits, the very first of which directly followed the numbers 1200. 

 

I must be seriously slow...

 

I uploaded that file years ago, and I didn't know until just now that it was searchable that way.  I'm going to guess @gwest_ca enabled that fine feature?

 

[Sutty 96]

Whoever did, it's going to be a grand help, so thanks to any concerned.

 

Done the setting now, 1200 it is, or 1177 as my tach said, when I gave up adjusting, because it was so cold in the wind outside. I had to put it outside to get enough light to see properly through the tach. That's the way these heli tachs work.

 

Before adjusting I checked the 800 figure from my exhaust puff counting, and from the inductive tach, and got just less than 800. Can't tell you the exact figure, below 800, because my tape was nearly stable, but tracking round slowly, and I couldn't go any slower on the tach, because 800 is its lowest setting. Going the other way with the tach resulted in faster tape rotation, so I had been homing in on it, until my lowest setting of 800. I tweaked the idle up, just a tad, and synched the tach, for stationary tape, and got 850, so I know it was definitely just less than 800 before I tweaked it.

 

Used the tach, very briefly, to check the Kohler Command 23 idle on the Cub Cadet, whilst I was there, no tape, just made the logo on the top stop spinning, and got 1950. I'd been thinking that was a tad fast, so I'll have to look that up too. I went all the way up from 800 and found no other stationary point, so I think it's right. I did rush a little with that though, because I was literally shaking with the cold. I can do it more carefully when I get the correct figure for that engine.

[Sutty 96]

My Kohler CV23 should be 1200 rpm at idle too, so that's been far too high. I kept thinking it was, and did nothing about it. Glad I've gone through this exercise, and thanks to all who have helped me get there. Only thing that remains to be solved now is how many sparks per revolution on the quad, so that I can read that correctly. I have a manual, so hopefully I can work that out from there.

[TractorEd 633]

@Racinbob I have a similar tach as you

 

 

used it last week on a C-161 and worked fine.  Then I put it on the C-100 and the rpm’s it reported were double what they should have been.

 

Would someone please explain what would/could cause that?  Both Kohler K Series engines, one 16 hp and the other 10 hp.  Tach was set to 4 stroke 1 cylinder for each.

 

I month or so ago I took the older coil, condenser, and starter solenoid off the C-100 and put them on the C-161; I bought and put new stuff on the C-100. Both still points run off cam.

 

@RED-Z06

 

What’s causing the C-100 to fire twice as often?

 

Thanks, Ed

Edited February 25, 2023 by TractorEd

[Sutty 96]

If that's an inductive type, did RED-Z06 not explain that in an earlier post in this thread?

[Racinbob 11,070]

41 minutes ago, TractorEd said:

@Racinbob I have a similar tach as you

 

 

 

used it last week on a C-161 and worked fine.  Then I put it on the C-100 and the rpm’s it reported were double what they should have been.

 

Would someone please explain what would/could cause that?  Both Kohler K Series engines, one 16 hp and the other 10 hp.  Tach was set to 4 stroke 1 cylinder for each.

 

I month or so ago I took the older coil, condenser, and starter solenoid off the C-100 and put them on the C-161; I bought and put new stuff on the C-100.

 

What’s causing the C-100 to fire twice as often?

 

Thanks, Ed

 

Mine doesn't have the induction feature so there's no settings to change. 

[Sutty 96]

Just thought I would report back with my final findings. It turns out that my quad bike has crankshaft/flywheel timed ignition and not camshaft and I have just had it confirmed that for use on my quad, the meter must be set to 1P1R, because it does indeed have a "wasted spark ignition" system. These words exactly as quoted by the guys in the Suzuki forum, with the further description that there is a wasted spark at the very top of the exhaust stroke, making it one spark for every revolution.

 

Had it not been for the contributions here, specifically @RED-Z06 , I doubt I would have known what, or how, to ask them.

 

I'm so pleased with the help I've received here. I can now easily check RPM on my Wheel Horse and Cub Cadet Kohler engines, and on my Suzuki quad.

 

Brilliant, thanks.

 

Best regards

 

Sutty

[TractorEd 633]

23 hours ago, Sutty said:

If that's an inductive type, did RED-Z06 not explain that in an earlier post in this thread?

Both the Kohler engines I’m testing are cam driven K Series engines with points.  So they should both spark every other revolution, but the tach says it ain’t so on one of them.