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Bad Vibes Maaaaaan!
Blog Date - 01 May 2025
Regular folks will know Sharon was suffering from bad vibes on her new Z500. Not the transcendental cosmic bad vibes from cheesy 60s and 70s movies but real vibrations. There were/are 2 different sets of vibes. One was a rattle somewhere around the engine at almost exactly 2,900 rpm. The other is a harshness through the bars as she approaches motorway speeds.
Let us deal with the first one, the buzz, the almost a metallic clatter at 2,900 rpms. This did not start until we fitted the engine bars - therefore it would be logical to presume something about the engine bars had lead to this rattle. It is not beyond the realm of possibility it could be something else, but it seems mostly likely the engine bars.
The Z5 is slowly but surely getting "tour ready".
We retorqued the bolts that hold the engine bars to the frame. Nope. We listened carefully, we touched and grabbed things, we stood in different places, plugged this ear then that, pushed things, pulled things, shook things, and all to no avail. While always replicable keeping the motor at exactly 2,900 rpm was also proving difficult.
Eventually with guidance from this here blog and the interweb we removed the left engine bar - because the noise seemed to be oh-so-slightly louder on the left. Gone! So it's definitely at least attributable to the engine bars, particularly the left engine bar. Well that's something at least, I thought the engine internals were falling apart.
We both agree we desire to keep the engine bars fitted because even a simple topple in a car park can put a hole in the side of a crankcase and ruin a holiday as well as a bank balance. But that rattle is driving Sharon bonkers and Sharon moaning about it is driving me bonkers. Oh what to do!!
Science innit. Rattles of this nature at a particular rpm are due to resonances. Resonances? Yes. A park swing has a resonance, a pendulum has a resonance, a ruler held against a desk and twanged has a resonance. If you push a park swing in time with that resonance it's easy to really get that swing swinging high, we seem to understand that almost instinctively.
Well at 2,900 rpms between the engine bars and the rest of the bike something somewhere is meeting it's resonant frequency and getting all carried away. We need to change something about the engine bars to change the frequency and/or dampen the vibrations. I get to thinking about running a strap between the left and right engine bar, fitting bags to the engine bars, fitting weights, all kinds of hairbrained notions.
Then Sharon, bless her, says "worrabout fillin' it with sand?" Now don't be thinking she's a genius, she'd read somewhere online that someone had done this successfully. Nah... no, hmmm... wait, errr...actually that's not as stupid as it first seems. The sand will change the weight of the engine bars AND, AND also act as a dampener. Hmmmm, this might just work.
Due to the design of the left engine bar we cannot fill the main structure - without drilling holes in the tubing at least. We can however fill one side of the cross tube which I shall try to show in a delightful image. This tube has an open end see. That being said an open end also means the sand would all too swiftly fall right out again.
Fill this section with sand?
We need a bung to keep the sand in. A big blob of epoxy resin? We ain't got any right here right now and I wonder if expansion and contraction of the tube would eventually loosen the bung. A rag stuffed in there? Nah. We scour Sharon's cupboards for potential bungs. "Rubber" says I "something rubbery". Sharon returns from the shed with 2 tank mount rubbers, the origin of which escapes both our memories.
We think it's a tank mount rubber doodaa whatnot.
"Sharon that sand needs to be dry, we don't want to encourage rusting from the inside". Sharon sits gleefully blow-drying the sand she's found from some garden project for half an hour. With 2 washers and a M6 bolt, the judicious use of scissors and a nyloc nut I craft an expandable bung. Essentially the rubber is pushed into the sand filled tube and the nut/bolt tightened thus squeezing out the rubber.
Tighten the nut(s) which squeezes out the rubber making a bung.
The engine bar has gained some mass. It is duly refitted to the bike and the engine started. At 2,900 rpm the rattle has gone! There is still a minuscule residual notion of a rattle but nothing that could be noticed as anything other than the regular shakes and shudders from any machinery. Woohoo!
So - the other vibration?
Sharon is now complaining of vibes through the 'bars at motorway speeds. I take the Z5 out for a blast and sure enough it's not like the bike is trying to disassemble itself at 70 but it feels harsh and buzzy rather than the silky smooth you experience at say 55. Hmmm.
Quite some time ago I purchased a CLR125 City Fly from a friend who was still on L plates. The bike ran just fine and dandy with 10,000 miles on the slock but I noticed when I got it above 55 it was harsh and buzzy too. With my friend being a learner and the bike being used mostly for town commuting I daresay this bike had seldom seen 55 and above. After a few months in my abusive hands I noticed the vibes had subsided at these higher speeds.
It were a reet gud bike my City Fly
I have a working theory - it's as though *SOMETHING* needed bedding in at higher speeds. Clutching at straws perhaps there's a few microns of barrel that aren't reached until the piston is moving fast enough to fling the piston a micron higher and lower. I don't know...
When I'm on the motorways with the CB500X I'll cruise at 55-60 happily, keeping with the trucks in the left lane and relaxing, not stressing about speed limits and changing lanes and drinking fuel and wearing out tyres. When I get up there to 70 my CB500X feels harsh too, buzzy and busy and annoying.
I've made a point these last few years to ensure I get the damn thing up to speed more often. It helps clear the engine, gives the motor a chance to breathe and clear it's lungs. I'll do 5 or 10 miles then drop back to my leisurely pace. Having done this I've noticed it's less vibey and harsh. Again it's as though the last bit of running in is finally done.
Sharon got her Z5 with about 360 miles on the clock. She's been sure to keep the revs down until the Z5 passed the 600 mile mark and now we're gradually building the revs. I am wondering and hoping the harshness at motorway speeds will pass as it has in the previous examples. We shall monitor the situation.
I get the feeling Sharon is slowly but surely coming to terms with the loss of the much beloved Z4, and slowly but surely coming to terms with the Z5. Maybe she will come to love the Z5 too one day? Again only time will tell.
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Reader's Comments
Upt'North ¹ said :-
Well done you mechanicing urchins.
Grip puppies, just sayin.
Upt.
06/05/2025 16:14:59 UTC
Bogger said :-
Yes, grip puppies may well be the answer.
However is if Sharon is used to gripping handgrips of a smaller diameter.
She may struggle with the extra girth. Ooh err Missus.
Bogger
06/05/2025 21:05:41 UTC
Upt'North ¹ said :-
I thought it, you said it!
Bad boy Bogger. Shouldn't you be off somewhere with your tiddler.
But yes, the extra "girth" is noticeable at first but you soon get used to it. I went to Grip Puppies when cramp and trigger finger was becoming an issue, all problems disappeared overnight. If you're tempted use the zip clip method of fitment. You only have to use two clips as the rest are still usable afterwards.
Upt.
07/05/2025 09:37:28 UTC
Ian Soady¹ said :-
"I've made a point these last few years to ensure I get the damn thing up to speed more often. It helps clear the engine, gives the motor a chance to breathe and clear it's lungs. I'll do 5 or 10 miles then drop back to my leisurely pace. Having done this I've noticed it's less vibey and harsh. Again it's as though the last bit of running in is finally done."
The old Italian tune-up.
07/05/2025 10:02:29 UTC
Ren - The Ed¹ said :-
As for grip puppies - subject to your innuendo and rude comments - I'd be tempted to give 'em a try. Not because of vibrations but because I've always thought 'bars need to be a bit thicker. How do they go on in the rain? Do they get sodden - I'm thinking will this transfer to the glove palms too.
As for the old Italian tune-up Ian - quite so. I would never suggest engines should be run at full throttle all the time but I do think they need "a damn good thrashing" once in a while. The problem is - especially with vehicles that offer a lot of performance - where can you give them a damn good thrashing legally? A 125 out in the countryside can be thrashed legally but even a 250 at full chat would see your licence in trouble. You can firmly accelerate up to speed but once there do you leave it in 3rd and revving wildly?
07/05/2025 13:16:47 UTC
Upt'North ¹ said :-
Can't say I've had a problem in the wet Ed.
They must absorb some moisture but I've never noticed. If it's raining that heavy you're probably soaked through anyway. Or at least half-soaked.
Plus how often do you get seriously wet.
Our last jaunt saw three proper wet spells in 4 weeks, the comfort payback and lack of vibes is well worth any extra dampness. Although they do feel odd at first.
Upt.
07/05/2025 16:33:13 UTC
Bogger said :-
Never noticed a problem with Grip Puppies in the wet.
They can literally transform how a bike feels, in a good way.
Try some and if they ain't for you ditch em. I do know they cost a LOT of money £15.00 FFS.
Bogger
07/05/2025 20:27:28 UTC
Upt'North ¹ said :-
OMG, Bogger has gone off his little nut.
£15.00 is not be be joked about, Ed is gonna ban ya.
Yes he is.
£15.00.....ban him Ed.
On that note I'm still banned from a certain US of A driven Honda Pan European forum. It's probably for the better, I mean I wouldn't want to be in any club that would accept me as a member.
Except here of course!
Upt.
08/05/2025 08:52:15 UTC
Ren - The Ed¹ said :-
I must admit I've been feeling rather out of sorts since Bogger suggested I spend... I can barely say it... £15!
As for you being banned Upt' - what terrible and repulsive thing did you say to get banned? Please bear in mind we like to keep things here family friendly. I can only imagine you suggested that your Wee-Strom is actually better?
08/05/2025 14:52:26 UTC
Upt'North ¹ said :-
It didn't involve insulting Pan Europeans, indeed why would I, they're a fine motorsiccle, in a behemothie sort of way.
No not that, but I'm glad you asked, I mentioned Trump, Tariffs and Tosser in the same post, arrange those words how you like.
Then when reprimanded by the head boy Ed, I remembered the ramblings of that Irish geezer George Bernard Shaw. Who famously argued that censorship stifles progress. He believed that censorship exists to protect the status quo by preventing challenges to existing ideas and institutions. He famously stated that "the first condition of progress is the removal of censorship," implying that allowing free expression and the open discussion of ideas is crucial for societal advancement.
Well, apparently not, like he said, "Assassination is the extreme form of censorship."
Pffffffftttttti'ttttty Pffffffftttttt.
Upt.
I prefer it here anyway, there's no one telling us to remember to fly the stars and stripes.....AGAIN!
08/05/2025 16:26:15 UTC
Ian Soady¹ said :-
Funny isn't it how those people who bang on about free speech seem to be the first to complain when their pet subjects are criticised. I'm not entirely with the venerable GBS - the classic example being "is it OK to shout "Fire" in a crowded cinema" but generally he was pretty spot on.
08/05/2025 17:01:07 UTC
Ren - The Ed¹ said :-
Surely you all have your flags attached to you motorcycles?!?! How terribly unpatriotic of you.
On a more important note - I hate brakes. Seized. Again. This time really bad. I must have a special magic brake seizing aura about me. Pffffffft.
09/05/2025 08:10:53 UTC
ROD¹ said :-
I don't think that a magic brake seizing aura is necessary, just UK winter riding and lack of maintenance is usually sufficient.
09/05/2025 09:55:08 UTC
Upt'North ¹ said :-
What part/s are seizing Ed?
09/05/2025 12:24:33 UTC
Ren - The Ed¹ said :-
You're quite right ROD.
Upt' - the front brake calliper is of the sliding type and of course the primary slider is stuck. Now normally they're a little stiff requiring a significant number of blows from a rubber mallet to persuade the slider to slide, allowing the brake calliper body to come away from the brake hanger.
This time round... success... of a sorts. Blowlamp, hacksaw, drill, big hammer... and so on and so on. I shall be ordering some parts...
09/05/2025 14:39:21 UTC
Upt'North ¹ said :-
Is that slider the fixed one? (Is that an oxymoron). If so are you stuck with oem?
Upt.
09/05/2025 18:34:46 UTC
Ren - The Ed¹ said :-
In this instance the slider in question is fixed to the calliper and slides into a socket on the hanger. Fear not, I have a used calliper and hanger en route.
Pffffft
10/05/2025 08:36:51 UTC
Upt'North ¹ said :-
Yes, I thought that was the offending miscreant Ed. I was going to suggest some expensive exotic material to replace the removable caliper pins, but I'm not sure anybody supplies such exotica for the fixed ones.
You'll know.
You know everything.
Blummin know it all.
Upt.
10/05/2025 09:51:27 UTC
Bogger said :-
Used Caliper OMG it'll be a bad as the old one.
Just buy a new one.
Bogger
10/05/2025 15:04:48 UTC
Ren - The Ed¹ said :-
The replacement only has 5000 miles on it not 54000 Bogger.
I have fudged a DIY replacement and it works... But I don't trust it Upt'. Apparently brakes are important? At the speeds I ride I could just put my feet out.
10/05/2025 18:03:38 UTC
Ren - The Ed¹ said :-
Oh and a new calliper complete is £800. The bike is barely worth that.
11/05/2025 04:48:57 UTC
Bros Steve said :-
Ren I have grip puppies fitted to all my bikes. not had an issue with rain cos I spent a fortune on various waterproof gloves but they were an instant success for me as I suffer with my hands regardless of what bike it is.
I also bought some foam lever sleeves from Wemoto. Not everyone needs them but as I say they work for me.
11/05/2025 11:40:52 UTC
nab301 said :-
Seized calipers ? I tend to clean and grease said sliders with silicone grease annually or at least everytime I replace tyres , it has to be better than purchasing replacements !
Nigel
11/05/2025 12:13:07 UTC
Ren - The Ed¹ said :-
Annually nab301? I daresay my callipers are off and on the bike more than annually.
11/05/2025 21:19:25 UTC
Upt'North ¹ said :-
It's weird innit?
When did any of us have to remove the calipers annualy off a four wheeled contrivance to ensure the brakes work?
Perhaps we should.
Upt.
12/05/2025 09:33:43 UTC
Ian Soady¹ said :-
Out of sight out of mind. And most drivers wouldn't notice whether their brakes were working properly till they failed an MoT.....
12/05/2025 09:43:37 UTC
Ren - The Ed¹ said :-
It would be advisable to either check your car's brakes or get them checked annually - and not just the MOT check but the MOT check is a start. However... car brakes are made to last without major maintenance. Boots over the pistons - not on motorcycles. Sliders with proper boots not the flimsy paper thin rubber slider boots bikes enjoy.
13/05/2025 07:52:45 UTC
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