Author Topic: NGC Cancelling the parallel twin buzz  (Read 605 times)

Offline Canuck750

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NGC Cancelling the parallel twin buzz
« on: September 19, 2021, 02:00:58 PM »
Like many parallel twins the Laverda SF series can really buzz, I found riding for half an hour my right hand was numb, the bike has been tweaked and tuned as well as anyone can get it but still the buzz. A friend had a couple suggestions 1) check the front suspension and 2) add bar end weights.

So I replaced the original and probably worn out front fork springs with a pair of new Wurth progressive springs and added a 25mm tube at the top of mild preload.

I replaced the original hard style grips with a pair of cushioned fat style and installed Emgo bar end weights

Went for a couple hour ride in the country yesterday at 60 ~ 80 mph speeds,



Totally transformed the bike, very steady front end, almost no buzz, can ride comfortably at near 80 mph with one hand on the bars, I am shocked that a couple simple and relatively cheap items can make such an improvement to a bike!



The big downside to a perfect days ride was the left side cover went AWOL as I was exiting the highway back into town, took three passes, the last on foot to find the battered side cover, salvageable abut in need of some serious repair and repaint, damn! NOTE TO SELF - check the side panel screw is tight next time :thewife:

« Last Edit: September 20, 2021, 10:27:17 PM by Canuck750 »
48 Guzzi Airone, 57 Guzzi Cardellino, 65 Benelli 200 sprite, 66 Aermacchi Sprint, 68 Gilera 106 SS, 72 Eldorado, 72 Benelli 180, 74 Guzzi 750S, 73 Laverda SF1, 74  Benelli 650S, 75 Ducati 860GT, 75 Moto Morini 3-1/2, 78 Moto Morinii 500

Offline SIR REAL ED

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Re: NGC Cancelling the parallel twin buzz
« Reply #1 on: September 19, 2021, 02:20:30 PM »
Yep.  It is all about harmonic frequencies.

Little changes can have big results.  I've have good luck with inserting a Bar Snake in the handlebars.  Also with bar end weights.

Bar end weights are sometimes magic.  I know some who have filled their handlebars with lead or steel shot and epoxy to get the same effect.

What brand of handgrips are those?  I have never seen them.
« Last Edit: September 19, 2021, 02:56:29 PM by SIR REAL ED »
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Offline Canuck750

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Re: NGC Cancelling the parallel twin buzz
« Reply #2 on: September 19, 2021, 03:09:00 PM »
I bought the grips from Fortnine, they are very comfortable for my hands


https://fortnine.ca/en/driven-vintage-grips
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Re: NGC Cancelling the parallel twin buzz
« Reply #3 on: September 19, 2021, 04:28:19 PM »
 on my vintage Brit twins it is not the grips or pegs that I feel the vibration, it's the seat. My ass gets itchy from the vibration...And my vision can get blurry..l Stand on the pegs just enough to pick up my butt and  it's fairly smooth.Sit back down and my vision blurrs and my ass is on fire...tried more seat foam, fleece, but it doesn't make much difference

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Re: NGC Cancelling the parallel twin buzz
« Reply #3 on: September 19, 2021, 04:28:19 PM »

Online ray bear

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Re: NGC Cancelling the parallel twin buzz
« Reply #4 on: September 19, 2021, 05:05:37 PM »
No good losing your side cover, all my bikes that have hard to get panels I have a nylon fishing trace attached so that the cover doesnt leave the bike but long enough to let the cover hang out of the way so you can access what ever, Lost a lid off my FLHX electraglide some time back that has the silly removeable lid idea instead of a hinge  so I drilled a tiny hole in the tongue  where it goes through the retainer slot and put a small R clip in it. Ray
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Offline SIR REAL ED

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Re: NGC Cancelling the parallel twin buzz
« Reply #5 on: September 19, 2021, 06:05:39 PM »
I bought the grips from Fortnine, they are very comfortable for my hands


https://fortnine.ca/en/driven-vintage-grips

thank you for the information!!

If you find that your right hand is getting numb faster than your left hand, reducing the clearance between the OD of the handlebar, and the ID of the twist grip tube works wonders.  You can have all the vibration absorbing mass in the world in your handlebar, and if you have a lot of clearance between the handlebar and the twist grip tube (say .040-.060") the handlebar mass isn't doing much for the vibration your right hand will experience.

Use some UHMW tape to reduce the clearance to "zero," while not producing any friction that would prevent the throttle from closing due to spring force from the carb.

https://www.mcmaster.com/tape/

Type in p/n 76445A723 for 1" width or 76445A724 for 2" width

I posted this previously, and some thought it was BS (those who did not try it, I assume) while those who tried it appreciated the difference.

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« Last Edit: September 19, 2021, 06:20:42 PM by SIR REAL ED »
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Offline SIR REAL ED

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Re: NGC Cancelling the parallel twin buzz
« Reply #6 on: September 19, 2021, 06:11:35 PM »
on my vintage Brit twins it is not the grips or pegs that I feel the vibration, it's the seat. My ass gets itchy from the vibration...And my vision can get blurry..l Stand on the pegs just enough to pick up my butt and  it's fairly smooth.Sit back down and my vision blurrs and my ass is on fire...tried more seat foam, fleece, but it doesn't make much difference

Tony,

Have you tried rebuilding the seat with some rebonded foam? 

Great stuff.  Hard to believe all OEM seats aren't made from it.

Lots of articles out there describe the process and material.  If you re-use the original seat cover, only you and your ass will know the difference. 

Hopefully, your ass won't tell nobody.......   :wink:
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Re: NGC Cancelling the parallel twin buzz
« Reply #7 on: September 19, 2021, 06:24:03 PM »
No good losing your side cover, all my bikes that have hard to get panels I have a nylon fishing trace attached so that the cover doesnt leave the bike but long enough to let the cover hang out of the way so you can access what ever, Lost a lid off my FLHX electraglide some time back that has the silly removeable lid idea instead of a hinge  so I drilled a tiny hole in the tongue  where it goes through the retainer slot and put a small R clip in it. Ray

that is brilliant.  My mother used to do the same thing with my mittens when I was a kid.....
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Offline cliffrod

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Re: NGC Cancelling the parallel twin buzz
« Reply #8 on: September 19, 2021, 06:28:27 PM »
Good to hear you found some success and your lost side cover.  If it was my bike, I would think al those vibes were still there and had to go somewhere so they ganged up on the sidecover..


on my vintage Brit twins it is not the grips or pegs that I feel the vibration, it's the seat. My ass gets itchy from the vibration...And my vision can get blurry..l Stand on the pegs just enough to pick up my butt and  it's fairly smooth.Sit back down and my vision blurrs and my ass is on fire...tried more seat foam, fleece, but it doesn't make much difference

More true words ^^^ have never been spoken.  That's good stuff.
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Offline guzzisteve

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Re: NGC Cancelling the parallel twin buzz
« Reply #9 on: September 19, 2021, 06:29:28 PM »
There is a company that makes circular plates with a mercury tube that go on the motor and make it dead smooth. I've installed them and they work.
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Re: NGC Cancelling the parallel twin buzz
« Reply #10 on: September 19, 2021, 06:33:35 PM »
There is a company that makes circular plates with a mercury tube that go on the motor and make it dead smooth. I've installed them and they work.

I remember something similar used to balance wheels.  Tubes filled with oil and small ball bearings, IIRC.
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Re: NGC Cancelling the parallel twin buzz
« Reply #11 on: September 20, 2021, 02:56:32 PM »
There is a company that makes circular plates with a mercury tube that go on the motor and make it dead smooth. I've installed them and they work.
Do you know the name? What bike did you install it on?




Offline guzzisteve

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Re: NGC Cancelling the parallel twin buzz
« Reply #12 on: September 20, 2021, 03:08:43 PM »
Do you know the name? What bike did you install it on?




Got to look it up, I have the wrapper somewhere. Harpers sold it to go on the flywheel at ring gear bolts. The owner of the EV had a few on his old Harley with success. He noticed the same product at Harpers so I put one on. No vibration under power on acceleration, kinda real weird & dead smooth. It did work. This was back around 99 or 2000. Maybe someone else here bought one.
« Last Edit: September 20, 2021, 03:10:38 PM by guzzisteve »
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Offline rschrum

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Re: NGC Cancelling the parallel twin buzz
« Reply #13 on: September 20, 2021, 07:12:00 PM »
Norton had it figured out!
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Re: NGC Cancelling the parallel twin buzz
« Reply #14 on: September 20, 2021, 08:45:33 PM »
Do you know the name? What bike did you install it on?

IIRC, Amsoil used to make the one you could mount between your wheel and hub for automobiles/trucks.

The one that mounts on a motorcycle flywheel is very interesting.

Seems like a very different challenge than balance a tire/wheel.
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Re: NGC Cancelling the parallel twin buzz
« Reply #15 on: September 20, 2021, 08:50:54 PM »
on my vintage Brit twins it is not the grips or pegs that I feel the vibration, it's the seat. My ass gets itchy from the vibration...And my vision can get blurry..l Stand on the pegs just enough to pick up my butt and  it's fairly smooth.Sit back down and my vision blurrs and my ass is on fire...tried more seat foam, fleece, but it doesn't make much difference

If you ever get around to rebuilding one of your Brit bike seats, by tossing the stock foam and replacing it with rebonded foam, I would love to hear your impressions.  Hard for me to believe you would not consider it a great improvement.

How long does it take before your nether regions become irritated?  Hopefully, reading my posts doesn't create the same symptoms.... :wink:

Bead seat cover can sometimes be a significant improvement.
"If reading shite on the internet will trigger your head exploding, please wrap your head in Gorilla tape before logging on.  Thanks!!!"

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Offline Canuck750

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Re: NGC Cancelling the parallel twin buzz
« Reply #16 on: September 20, 2021, 08:54:16 PM »
Can someone educate me on 'rebonded foam' I have never heard of it and I need to get the seat foam replaced in my Laverda and Moto Morini.

Thanks!

Jim
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Offline Canuck750

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Re: NGC Cancelling the parallel twin buzz
« Reply #18 on: September 20, 2021, 10:30:57 PM »
https://foamforyou.com/multi-rebonded-mixed-foam.html

Thanks Charlie! I recognize that product, should be able to find it around here.

Thanks Ray Bear for the tip securing the side panel with a fishing line leader, the fine braided steel lines with clips on each end should do the job!
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Re: NGC Cancelling the parallel twin buzz
« Reply #19 on: September 21, 2021, 01:42:00 AM »
If you ever get around to rebuilding one of your Brit bike seats, by tossing the stock foam and replacing it with rebonded foam, I would love to hear your impressions.  Hard for me to believe you would not consider it a great improvement.

How long does it take before your nether regions become irritated?  Hopefully, reading my posts doesn't create the same symptoms.... :wink:

Bead seat cover can sometimes be a significant improvement.
  Oh, maybe 5 minutes at 75 mph...Other Triumph guys have ridden the bike and remarked how smooth it is for an old Triumph...So maybe it's just me. A few years back I built a cafe type 70 Bonneville. I made a seat with a shaped plywood base on 3/8 thick rubber mounting pads that was similar but shorter than the stock seat...I used rebonded foam, two inches thick, vibration blurred my vision,. added an expensive anti vibration gel pad...was still the same....maybe it's just me....

Offline SIR REAL ED

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Re: NGC Cancelling the parallel twin buzz
« Reply #20 on: September 21, 2021, 04:32:59 AM »
  Oh, maybe 5 minutes at 75 mph...Other Triumph guys have ridden the bike and remarked how smooth it is for an old Triumph...So maybe it's just me. A few years back I built a cafe type 70 Bonneville. I made a seat with a shaped plywood base on 3/8 thick rubber mounting pads that was similar but shorter than the stock seat...I used rebonded foam, two inches thick, vibration blurred my vision,. added an expensive anti vibration gel pad...was still the same....maybe it's just me....

If other Brit bike owners say your bike is smooth, that does sound like you have some unique physiology.  Does wearing tight or loose pants help matters?  The effect of blurred vision caused by vibration is interesting.  I wonder if it could be reduced blood circulation or a sitting related posture issue.  I'm not sure normal sitting posture is very similar to sitting on motorcycle. 

I know some swear that the extra "support" given by wearing tight fitting bicycle racing shorts seems to reduce fatigue.

I would try some bizarre experiments just to see if there is any effects or changes.  Say compression socks, compression shirts, bicycle racing shorts, a truss or a weight lifters belt, etc.
 
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« Last Edit: September 21, 2021, 06:29:20 AM by SIR REAL ED »
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Offline guzzista

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Re: NGC Cancelling the parallel twin buzz
« Reply #21 on: September 21, 2021, 04:40:50 PM »
Guzzi content .  For Tontis such as T3/T4 G5, Convert and LM1/2 , this is my solution to prevent side covers from going AWOL.



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