Thread Number: 34529  /  Tag: Brand New Vacuum Cleaners
Kirby Avalir- higher speed than prior models?
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Post# 373312   6/6/2017 at 08:15 by reo580 (Holland, Michigan)        

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I just bought an Avalir for my birthday and I am in love with it.
I noticed that it has a smoother transmission than my Diamond and G6 did.
it sounds like it runs at a higher RPM rate than any of my prior G models (and Diamond on high speed) did.
Anyone else notice this?
Does Avalir run at a faster speed than the prior models?

My avalir has a rattle when the hose is used that I do not like. I can feel a slight vibration on the motor unit when the hose is on. I rebuilt many, many Kirbys before but never tore into the Sentria-Avalir models.

I am going to replace the fan and shaft.The shaft has a very slight wobble to it on the wind-down. I am considering replacing the armature which made me wonder if Sentria II and Avalir had different field coils and armatures than the prior models.

Could it be a bent fan shaft?
Thanks for any info.
, Derek

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Post# 373313 , Reply# 1   6/6/2017 at 08:37 by Kirbysthebest (Wichita, KS)        

Since you just got it, it should still be under warranty.  I would seek out a authorized distributor and have the repairs made by them at no cost.


Post# 373338 , Reply# 2   6/6/2017 at 13:32 by sptyks (Woburn, MA)        

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Believe it or not the Avalir has the exact same motor as the G3 had. The airflow was increased to approx. 137 CFM by redesigning the Mini Emptor on the Sentria II and Avalir. This would most likely be why the Avalir sounds different than older models.


I doubt if the motor is to blame for the vibration. I would have the fan and belt pulley shaft replaced under warranty by your local Kirby dealership.

Post# 373351 , Reply# 3   6/6/2017 at 15:36 by wyaple (Pickerington, OH)        
Yes, the motor RPM is greater in Kirby's newer models

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I don't exactly when (maybe the Sentria I or Diamond edition), but Kirby definitely increased the motor speed. You can easily hear the pitch difference in my videos of the G6 and Sentria II. I'm aware that the motor part number is the same, but manufacturers make little tweaks all the time...

Here's a pic of an FFT program showing a lower RPM for a G6 versus a Sentria II. BTW, my G4, G5 and G6 all run at the same speed. For those musically inclined, the newer Kirbys sound about one half-step higher than the older G series.


Post# 373410 , Reply# 4   6/7/2017 at 11:10 by sptyks (Woburn, MA)        

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That looks like a fairly insignificant increase to me. Could it be that the older G series machines have dry motor bearings reducing RPM? I wish there were an easy way to measure motor RPM so we can determine if there is a significant performance increase.





Post# 373411 , Reply# 5   6/7/2017 at 11:22 by sheetstyler (Mooresville)        

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My avalir I just got it and it sounds like it has more RPM. My doesn't have the problem with the shaft though. I am in love with my avalir it's an amazing machine I got it with the attachments and shampoorer for $80 don't regret it at all

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Post# 373415 , Reply# 6   6/7/2017 at 14:11 by wyaple (Pickerington, OH)        

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It's interesting to follow Kirby's evolution into higher performance over the years.

There is a 17 CFM difference between my G6 and Sentria II.

G6 Nozzle CFM = 120
Sentria II CFM = 137

Here's my partial guess as to how the 17 CFM increase can be accounted for:

--9900 RPM / 9300 RPM = 6.45% or about 9 CFM for the increased motor speed (BTW, that's with the brush roll spinning, not just the fan by itself with no nozzle attached.)

--Redesigned emptor allowing 8 CFM more airflow (Haven't verified this yet).

Total CFM increase = 17 CFM over the older G series machines. I'll take it!


Post# 373450 , Reply# 7   6/8/2017 at 11:23 by sptyks (Woburn, MA)        

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How do you measure motor RPM?





Post# 373458 , Reply# 8   6/8/2017 at 12:43 by vacuumdevil (Denver)        

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Looks like a insignificant increase to me as well . I bet your older G6 machine has worn and dry motor bearings.

Post# 373459 , Reply# 9   6/8/2017 at 13:48 by wyaple (Pickerington, OH)        
There are two methods I have for verifying

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dry motor bearings without removing them from the machine.

1) Current meter. Dry bearings will cause additional drag and cause the amperage to increase. I have a post entitled some like "How much power do they use" and you can see my measurements there.

2) FFT (sound) analysis. Since there are boatloads of Kirby videos on YouTube (including from the Kirby company itself), it is very easy to hear the increase in speed in the newer models.

I have a Heritage II Legend, G4, G5, G6 and Sentria II so far and I can assure you the bearings aren't dry (yet). Several years ago, when Kirby first released the Sentria II, I immediately heard the speed increase and wondered how much faster it was running. Well, using an FFT program called "Sound Analyzer", I am able to pin it down by placing a recording device (microphone, cellphone, etc.) at the rear of the Kirby in order to get an accurate reading with the brush roll actually spinning (under load).

Here's a slightly different screenshot showing more of the program's capabilities with me whistling. It can even pinpoint the frequency and decibel level if you desire.


Post# 373464 , Reply# 10   6/8/2017 at 14:46 by Kirbysthebest (Wichita, KS)        
Though I am not an engineer

I have taken a few Audiology classes in my day.  There a number of factors that can change frequency and pitch, without indicating an increase in speed.


With our constants being Fan of same size, and material, and motor of same design and amperage we then can look at variables.


One variable having been addressed, older motor with thicker grease, or worn bearings. Verifiable by no load amperage draw.


The redesigned, and shorter air path of the Avilir can be one cause.  Looking at the human voice, discounting the size of the  Larynx which will vibrate slower for a male than a female (Frequency).   It is  the size of the vocal tube and resonating cavities which are shorter in females and children, thus vocals  higher in pitch.   


I hypothesize that the redesigned emptor and shorter air path of the Avilir is not only a factor of the increased CFM, but also the rise in pitch.   Without knowledge of what RPM difference that is required to raise the frequency, I could also hypothesize the other factors, motor age, etc. could influence your end results. Though we focus on the older model and it's bearings, since you also noted a rattle effect, I could question the bearings on the Avilir.  It is possible to have a tight, or squealing bearing on a new, or relatively new machine. 


Have you ever switched the bag system from the G6 to the Avilir and vise-versa to see if you notice a difference? 


As far as measuring RPM on a small motor be it electric or gasoline, is difficult.  May be a good question to pose directly to Kirby, and see if they respond.


Please let us know what you discover.





Post# 373482 , Reply# 11   6/8/2017 at 19:44 by texaskirbyguy (Plano, TX)        

The easiest way to measure RPM is with a non-contact tachometer. I have done this with all the vacs I have restored just for fun and general info. I had originally bought the tool for vintage phonograph and turntable restos.
Harbor fright has an inexpensive one that I found quite accurate. I made a a round disc from black cardboard, poked a hole in the center, and pressed it onto the motor shaft. The reflective tape is then stuck to the disc. Fire it up and take the reading, holding the tool steady. To measure with the brushroll on, wrap black tape to one section and stick on the reflective tape. Power on and take the reading. Measure the brushroll diameter and motor shaft diameter and find the ratio. Then extrapulate the motor RPM.

Post# 373536 , Reply# 12   6/9/2017 at 14:20 by sptyks (Woburn, MA)        
Kirby G series motor speeds

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I spoke to a Friend who has owned a Kirby dealership for many years and he really knows his stuff.


Fact: ALL G series motors from G3 to Avalir not only have the same part number, but they all have the exact same Armature and Field Coil. In other words, no changes have been made to the motor itself.


The changes to RPM and pitch can be mostly attributed to changes in outer bag material and a much cleaner air path due to the design of the newer mini emptor.


I expect that the older emptor design caused some back pressure in the fan chamber slowing the motor down somewhat. The new mini emptor alleviated this problem allowing the motor to reach it's max RPM. This would prove Harley's assumptions to be correct and also account for Bill's increased pitch measurement.



Post# 373548 , Reply# 13   6/9/2017 at 19:21 by wyaple (Pickerington, OH)        
Finished Bag and Emptor Tesing Today

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After testing just the Sentira II and G6's outer bag/emptor setup, I continued testing with G5 and G4 assemblies as well. The tests were run with the brush roll spinning and the same (never used) HEPA bag inserted into each assembly. Drum roll please....

Relative to the Sentria's outer bag/emptor setup:
Sentria II airflow loss = 0 (default)
G6 airflow loss = 8.2 CFM
G5 airflow loss = 12.3 CFM
G4 airflow loss = 13.3 CFM

So this means that the "missing" 8 CFM from my previous estimation has been found. To recap:

CFM at the nozzle difference of 17 CFM from a G6 can be accounted for by two changes in the Sentria II/Avalir.

1) 9 CFM increase by the motor running at a higher pitch (faster RPM) and
2) 8 CFM increase by the outer bag/emptor having greater flow through capability.

It should be noted that by carefully wrapping the HEPA bag around the filltube so it gently surrounds it from top to bottom (like a hot dog in a bun) paying particular attention to removing creases, I was able to push my Sentria II to a whopping 138.7 nozzle CFM.

Below is a picture of today's contestants:

Post# 373705 , Reply# 14   6/12/2017 at 08:16 by Reo580 (Holland, Michigan)        

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You are right: the Avalir takes the same armature as the G-series.
I replaced the armature, front bearing and the fan and shaft ( might as well since I got this far) and now it runs perfect in both carpet and hose mode.
I couldn't stand the vibration it had earlier. One of my friends said it sounded like a Kirby. I could hear a viberation / frequency that sounded off to me. I Couldn't live with it. Now I'm happy with it.
This thing cleans well and I like its looks too.
Many thanks to Kent Oyler @ Kirby Needs for quick, professional service!! I got the parts I needed and they arrived quickly. My Avalir and I thank you.

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