Vibration through 'bars on deceleration?

Bonzo

Bonzo

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I'm just getting to know how this bike rides and one area I need to address is an annoying vibration felt through the handlebars and foot pegs when I come off the throttle, approaching a junction, coming to a stop, changing down etc.

Elsewhere, vibration is felt when starting off, though to a lesser extent, up to about 2,800/2,900 rpm when the vibration stops, the mirrors become useable, and the ride is smooth and linear. Also, cruising along at a steady throttle is blissful. I reckon this is pretty normal, it's when I'm off the throttle that is the issue I'd like to dial in/out. It's not unrideable, far from it, but I'd like to try to eliminate the tingling.

Where should I start?

It's a mk2, but with the AN adjustable front & rear Iso. conversion. The HS is the standard rubber mounted assembly (I actually have a Dave Talyor HS and mk3 spring set up sitting in a box, but I haven't fitted it until I knew what - if anything - needed to be improved).

I don't know if I'll get chance to get out with the bike today as I have other stuff to catch up on, but thought I'd ask the question.
 
Bonzo,
I am with concours on this. I don’t think that a new head steady and the Mark 3 spring are going to eliminate the shudder you are experiencing.Enjoy your blissful ride as it sounds like your bike is well set up.
Mike
 
look around for witness marks showing an isolated part is touching a non isolated part especially towards the rear of the bike. On the overrun the drive train (not just the chain but gearbox and primary) is being flexed differently from when under acceleration or cruising hence if 2 parts are very close they may touch on the overrun but not any other time.
 
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In your boots, I would install the parts in the box, then reevaluate the situation. The deceleration vibration could mellow to a tolerable state with the HS change. Go over and tighten every nut and bolt on the bike especially in the engine and gearbox cradle area. Make sure your chain is not too tight.

Nortons vibrate period. It is possible to make a Norton engine vibrate less, but it requires taking the motor apart and changing a few things.

I don't notice this deceleration phenomenon, but I've owned a Norton for a long time, and am numb. ;)
 
+1 on what Schwany said. Plus, the new iso's may be stiff. You could try opening up the clearance, like up to .01" then dial it back if that's too soft
 
Thanks gentlemen.

All good points that make sense. I'll have a check over tomorrow.

Cheers :)
 
If bar vibes annoy you, you can reduce it.
I put 1.3kg of lead shot in and it definitely improved things. Apr 21, 2021
Cheers
 
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You got to remember steel handle bars are only thin wall, I stopped mine vibrating by putting a set of alloy bars with 6.5 mm wall or put solid bar up the end of the steel bars where the hand grips go.

Ashley
 
A cheap filler for stock steel chromed bars is clear silicon caulking. Pump it in there with a caulking gun. Filling the bars won't stop the motor from vibrating, but it is a slight improvement at the grips.
 
Bar end weights are supposed to help heaps with vibes through the bars. Same with placing some lead in the bar ends. Changes the resonance of the bars. Just need to play around with mass and position.
 
Providing the ISOs are in reasonable nick the Mk3 Spring will help eliminate the judder, that's its job. The vibes in the handle bars can be caused by a worn, dirty or stiff linked drive chain.
 
Tornado said:
Bar end weights are supposed to help heaps with vibes through the bars. Same with placing some lead in the bar ends. Changes the resonance of the bars. Just need to play around with mass and position.
Click to expand...
The ENDS is the answer.
 
Schwany said:
A cheap filler for stock steel chromed bars is clear silicon caulking. Pump it in there with a caulking gun. Filling the bars won't stop the motor from vibrating, but it is a slight improvement at the grips.
Click to expand...
I tried filling bars with RTV, no difference discerned.
I tried 7-1/2 shot, a bit better.
A weight at the end was a noticeable difference.
Disclaimer: NOT on a Commando
 
concours said:
I tried filling bars with RTV, no difference discerned.
I tried 7-1/2 shot, a bit better.
A weight at the end was a noticeable difference.
Disclaimer: NOT on a Commando
Click to expand...
I'd think position and weight amount will depend on the bar bend, material and even switch gear/other gubbins placement.
 
Well, as it turned out, I didn't get much riding time this weekend (despite it being an unplanned bank holiday), and so my fettling has amounted to precisely bugger all.

Was gonna take a ride out to our eldest's at his new gaff this avvie, but before I did thought I'd check the valves again as the timing side exhaust seemed to be a touch rattly (it needed a tweak). Went to start the bike and found fuel pAssing out of the l/h tickler. Stripped the bowl, checked the float, couldn't see a problem, put it back together again and its fine. New Premier's so can't blame it on any worn parts. Float could've just stuck I suppose. Taking it for its vehicle examination on Wednesday (like a one-time strict MOT), so need it to be bob-on.

I'll take it for a quick run out now because I'm gagging for a ride out on it.
 
Burrs on the float tang, causing it to bind on the needle and prevent proper action is a common ish problem on new Amal’s (Premier and MK2).
Finishing with a fine file and emery is the answer.
 
Fast Eddie said:
Burrs on the float tang, causing it to bind on the needle and prevent proper action is a common ish problem on new Amal’s (Premier and MK2).
Finishing with a fine file and emery is the answer.
Click to expand...
I'll bear that in mind Nigel, cheers.

Just took it out and the flooding issue hasn't reappeared, so I won't delve in again until I need to.

EDIT. Actually, I remember checking that (on your recommendation, I think) a while ago - before they went on.
 
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