Vibration issues

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daves71dream
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Vibration issues

Post by daves71dream »

Hi guys and gals,
Has anyone ever tried to reduce the amount of vibration we experience on these great machines by fitting handlebar end weights as fitted to todays bikes?
I realise an experienced engineer can give you the optimum balance by crankshaft balancing, but how about the end weights OR any other means.
I look forward to your replies.
Cheers
Dave
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Re: Vibration issues

Post by Canberra »

I have front end from a later Triumph with disc brake. The forks are wider and the handlebar is rubber mounted. It does remove the vibrations in the handlebar to some extent and I believe bar end weights would improve it again.

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Re: Vibration issues

Post by minetymenace »

So whats the plan? Rubber mount the bars and make them so heavy they stay still? Can't beat a bit of white finger
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Re: Vibration issues

Post by b50root »

Why under "P92 Tech"
Last edited by minetymenace on Tue Jan 28, 2014 10:48 am, edited 1 time in total.
Reason: Didn't notice that Rickard! Sorted
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daves71dream
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Re: Vibration issues

Post by daves71dream »

Canberra wrote:I have front end from a later Triumph with disc brake. The forks are wider and the handlebar is rubber mounted. It does remove the vibrations in the handlebar to some extent and I believe bar end weights would improve it again.

John
Hi John,
That sounds like a good solution, if i'm serious about reducing the vibes I should try the later Triumph front end.
My 1972 650 Bonneville had rubber mounted bars and I'm sure they helped keeping the vibes down.
It is something to consider for the future, and I might try the bar end weights anyway. I will let people know the results if and when I do.
Thanks for the advice. Cheers and safe riding to all.
Dave
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Re: Vibration issues

Post by minetymenace »

daves71drean, just re-read my post and it seems a little harsh, sorry. What I was trying to say is that adding mass to the bar ends is most effective at high frequencies and it changes the resonant frequency of the bars, they will still vibrate, but as long as resonance dosen't happen in the normal rev range, that is about as good as it will get. Rubber mounts will provide AV protection and the density of the elastic material should be chosen with the problem frequency in mind, this is the way to go. Its a single, it vibrates.
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daves71dream
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Re: Vibration issues

Post by daves71dream »

minetymenace wrote:daves71drean, just re-read my post and it seems a little harsh, sorry. What I was trying to say is that adding mass to the bar ends is most effective at high frequencies and it changes the resonant frequency of the bars, they will still vibrate, but as long as resonance dosen't happen in the normal rev range, that is about as good as it will get. Rubber mounts will provide AV protection and the density of the elastic material should be chosen with the problem frequency in mind, this is the way to go. Its a single, it vibrates.
Hi Minetymenace,
Thanks for your second post on this subject. Rubber mounted bars are as you suggest probably the way to go.
Canberra has found this helps,and so this looks like it will be a long term issue for me. I do realise that I'm never going to get a B50 to be as smooth as my F650CS BMW though.
Cheers,
Dave
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Re: Vibration issues

Post by maddkraut »

Are there any hardcore machinists who may have tried to fit balance shafts? Would be a big mod I am sure.
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Re: Vibration issues

Post by hwan »

Buy a K*wasak* W650 - same bore/stroke and feel as good a triumph, without the 'bits dropping off'/bungee-strap requirement.
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Re: Vibration issues

Post by Sly Dixon »

I filled the bars on my B44 with lead which changed the moment in the bars. Interestingly it means that the speedo only tells the true speed when my hands are off the bars. The bigest improvement came with balacing the crankshaft but its still a pretty buzzy machine at speed.
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Re: Vibration issues

Post by Victor500T »

hwan wrote:Buy a K*wasak* W650 - same bore/stroke and feel as good a triumph, without the 'bits dropping off'/bungee-strap requirement.
No, don't buy one of them! It's a myth that Triumph twins are serious vibrators. I have two right now, one of which I built entirely out of parts from god knows how many different machines, and neither of them vibrate much at all. Oh, and neither of which have undergone the expensive and dubious process of crankshaft balancing - all cranks were 'balanced' at the factory.
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Re: Vibration issues

Post by minetymenace »

Victor500T wrote:the expensive and dubious process of crankshaft balancing - all cranks were 'balanced' at the factory.
Back in the early 80's I was at the Lanch Poly in Coventry (riding my <12fs ). The local bike club organised a trip to the Trumpet factory just down the road at Meriden. I will always remember being introduced to Fred (or George or Bob or whatever his name was, that bit is not so clear), who was in charge of balancing cranks, he was about 134 years old. He stood next to a dusty dynamic balancing machine, and had a set of parallel bars, a Victorian pillar drill fitted with a 1/2 in bit, and a couple of spring loaded weights. He clipped the weights to the big ends, rolled the crank left and right, up and down the parallel bars, then graunched out a chunk of flywheel on the pillar drill. After three check rolls up and down the bars, another crank was tossed in the box on the floor. We were told that Fred (or whoever) could balance a crank better/quicker than the machine, but I suspect that either the machine had broken and they couldn't afford to fix it, or Fred couldn't find the "On" switch and was afraid of this new fangled electrickery.
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Re: Vibration issues

Post by Sly Dixon »

Mine had a B50 big end in a B44 crank. It was wildly out of balance. The difference between before and after the re balancing was that before the only thing you could see in the rear vision mirror was a brief flash as it was falling off whereas now it is possible to see other vehicles approaching from the rear.
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Re: Vibration issues

Post by beat »

minetymenace wrote: Fred couldn't find the "On" switch
well, - Fred celebrates this year the 177 anniversary and some of the cranks are still running !

lucky he did not find the " ON " switch.......

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Re: Vibration issues

Post by Victor500T »

Must have been Fred who did the crank on the T`120V I once owned, briefly. That thing was like a pneumatic drill. The clocks would vibrate their ways out of the rubber cups and start turning around and no bulb lasted more tha 20 miles. But that was the only serious vibrator of a Triumph twin I've had. Of all the rest, some have been a tad buzzy and some have been smoother than a Jap four.
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Re: Vibration issues

Post by beat »

:mrgreen: :mrgreen:
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Re: Vibration issues

Post by BSA_WM20 »

maddkraut wrote:Are there any hardcore machinists who may have tried to fit balance shafts? Would be a big mod I am sure.
balance shafts gobble up power.
H*nda tried it with the FT ? and it was a disaster and got dropped.
Not only was it slower off the mark than a C10 with side car, the counterweight drive wear a little then the thing internally self destructs.
Where as the SR which was concurrent with the FT went from strength to strength,
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Re: Vibration issues

Post by hwan »

WM20 ........ And every other bikes and cars fitted balance shafts ?????
You are actually trying to tell us, that a 8HP (on a good day) SV C10 + sidecar (!!!) is initially quicker than an FT500 !


Bar-end weights are a very common feature of non brit-bikes and are available for stuff like (Norton) Dominater's and Commando's.
The weight to be used will vary from bike to bike and handle-bar - so basically it would be a 'try & see' job to determine the actual weight will needed - note that the BMW ones are heavy, perhaps 4-8 ounce or so.

As far as i can see on my F650 (Rotax - WITH POWER SAPPING ? BALANCE WEIGHTS) the substantial bar end weights are to remove a particularly 'tingly' rpm around 5K - i know this because i removed the original wide bars and fitted the slightly narrower ST Strada bars.
These vibrated like hell and as i didn't get the balance weights with them, i swapped them back to the original PDQ - leaving the original bar-end weights off, for some reason ......
These were quickly replaced when i realized why they were there :???:

So, they could be useful to reduce vibs at a particular rpm.
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Re: Vibration issues

Post by stew79 »

i feel i must defend H*nda with there 500 single engines. (i have 2 in the shed) the very tuned down version of the xr engine that went into the ft was very wet, but still quite reliable. in 1982 yam started using counter balance shafts in the xt,s (thats were the sr 500 came from) and still use the same system in there latest singles. as for power the xr can make 50 to 60 all day long, with or with out the counter balancers.
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Re: Vibration issues

Post by hwan »

Exactly Stu !
I've had a number of H*nda's - I dont like them, but that's a personal thing - like all jap bikes, they work - full stop!
And dont give you vibration white finger in the process.

I suppose if you want to have a britbike experience without the vibromassage you could buy an early (no idea what the later ones are like) K*wasak* W650 - balance shafts + rubber mounts + h/bar weights (belt + braces + elastic waistband):grin:
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Re: Vibration issues

Post by Victor500T »

In my humble opinion those FT500 H*nda´s were extremely poor motorcycles, very slow and begging the question, why did H*nda make a 500 version of the excellent CB250RS that was no faster and used a lot more fuel! The 250RS had balance shafts. It was a little gem of an engine, certainly not lacking in power for it's size.
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Re: Vibration issues

Post by hwan »

Thats H*nda for you ........

One reason i dont like them, they seem to like using the customer for product development work - like the cheese cams fitted to early V4's.

And yes, the 250 was a damn good engine.

The off-road XR200/25/500's all are good enough bikes, but the bigger ones were sods to kick-start when hot!
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Re: Vibration issues

Post by minetymenace »

Might move these posts to the H*nda section if you guys don't stop pontificating about that brand...
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Re: Vibration issues

Post by hwan »

ooooooooooooooo - pontificating - that's a long word :grin:

I take it the H*nda section is round and bin shaped ?
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Re: Vibration issues

Post by Victor500T »

minetymenace wrote:Might move these posts to the H*nda section if you guys don't stop pontificating about that brand...
Good idea! Sorry about that, it won't happen again I can assure you! (I'd add a smiley thing if I knew how)
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