Sources of vibration?

[AMCQ46]

One of the remaining niggles with my bike is that I think it has a vibration problem which makes it a pain in the hands and feet if I am doing any distance on motorways with a constant vibration frequency. Back roads are fine as I am changing the revs all the time, so the frequency changes, and I have other factors to keep me distracted from the vibration.
Feels worst at about 5000 revs in any gear.

I remember the bike being smoother when I first bought it 10yrs ago, but the vibration started about 4yrs ago, and has stayed about the same since then, but I have vowed to fix it this winter! so the question is where should I be looking?

Traditional sources and fixes I have thought of are:
1) Chain tight spot.........I will be changing the chain, but I dont think this is the cause, as it is engine speed dependent not road speed.
2) Exhaust mountings loose........that would be a reason for vibes in the foot pegs but not the bars, and I have also tried tightening them with no improvement.
3) engine mounts loose........Anybody got the special tool I can borrow? or is there a good way to make one up?
4) Cam timing out 1 tooth.......would this cause a vibration?.........I will check anyway, but interested in your thoughts.
5) Balance shaft............I cant see one in the workshop manual, but is there a balance shaft on the storm and is it possible for it to lose its timing to the crank position.
6) Carb balance...........will look at this again, but is it possible that this will cause a problem at high revs?
7) ............what else do you think? .......Clutch basket out of balance [you all know I have the grabbing clutch problem, so could there be a common link], Main bearings on way out etc. etc.

Other than the vibration, the engine runns great, so would like to get this fixed.

[pinkyfloyd]

Dont know enough about bikes to give you an answer but the first thing that springs to mind is front wheel bearings. From another forum I post on that seems to be the cure for excessive vibrations.

[pariah]

When I had a small amount of oil leak when at low speed. I thought that only losing a small amount of oil wouldn,t have caused any problems . The oil light never came on and went out straight after starting the bike up again so oil pressure was fine.
When riding back home after filter change and topped oil up I noticed extra vibration, ? It's very bad now , even the passanger can feel it . No other problems with the bike, starts and runs ok Just that at around the 5000 mark you can feel the vibration really bad. I have spoken to roger ditchfield and he says it because the small lack of oil has picked up one of the shells on the right hand side and is now causing the vibration .

Just my 2 pence worh, speak to roger first.

[warby221]

Not wanting to alarm you too much but if you check all the other things fist and can’t find the answer
check the oil pressure when hot then get back to us if its low

[tony.mon]

Try a compression test.
My money's on low compression on the front cylinder.
Once one cylinder has noticeably lower compression than the other it vibrates like a single! The engine will still run ok like this, it's only if you ride another bike back-to-back you notice the lack of power.

I have one of the two special tools you need for the frame bolts; the smaller of the two.
I borrowed the larger one when I wanted it, but next time I need one I'll make one with an old socket. The big one's easy to drift round anyway, as it's not recessed in wells in the frame like the other two.

There's no balance shaft, but just possibly if the primary tensioner gear (spring-loaded on the RH end of the crankshaft behind the timing sprocket) is not properly set that might just give the symptoms you describe.

Clutch basket that far out of balance is unlikely.

Cam timing out? Possible, but fairly easy to check.

Thought about wheel balance? (although if it's been like this for four years I'm assuming you've changed tyres and had them balanced).

Carbs not properly seated/sealed, or not functioning correctly- borrow a spare set and try them to see if this affects it.

Loose/flapping fairing? Any damage? Are the two small pushfit clips in place under the oil cooler?

Bingo wings flapping in the breeze?

Lastly, I found that the standard cans made the pegs vibrate, and if you have changed the bar-ends the internal bar weights might not be tight, or there at all.

[benny hedges]

your mrs pushed a vibrating love egg up your butt while you were asleep and it's been there that long the battery has gone flat and you forgot about it.
but as your bumhole is perched right over the storm's battery, it's inducing a current at high rpm, up through the seat & is revitalising the long lost marital aid.
apparently they have a bit of string attached to them so maybe you could get some margarine on a rubber gloved hand and have a good fish about, see if you can tug it out.
i'm sure she'll be glad to get it back after all this time.

[AMCQ46]

I have spoken to roger ditchfield and he says it because the small lack of oil has picked up one of the shells on the right hand side and is now causing the vibration .

Yes I had seen that thread and that got me a bit worried, my only hope is that it has never gone low on oil, and my wheelies arnt that good that I could have starved it of oil.

Tony,
I will add compression test to my list, are you thinking valve damage?, and I might take you up on borrowing the special tool to torque up the engine.

Dont think it is wheel balance, as you say I am on my 3rd set of tyres and it goes away if I pull in the clutch, that is also the reason I dont think it is wheel bearings either [and I have checked for roughness when the wheel is spinning with the calipers removed]

Didnt think about carbs seating, but will give that a good look over when I check the cam timing.

Fairing undamaged and all clips in place

Bingo wings..............I dream of growing them ...........I make kevin schwantz look like a porker

Sill got std bar ends, but I can rotate them, not sure how the internal weights are fitted, so any more clues there?

Benny,
I will check for string, as there was one camping weekend where I may have passed out..............oh hold on, that wasnt me

[tony.mon]

Tony,
I will add compression test to my list, are you thinking valve damage?, and I might take you up on borrowing the special tool to torque up the engine.

Wasn't thinking valve damage, (however it's possible, but not as a result of low oil) but the front piston often wears on these engines and the balance goes out.
In fact, I have now stripped four of them and the front cylinder had lower compression that the rear on all four.

I believe that this is because the front cylinder wall is not receiving as much oil spray under hard acceleration and during wheelies, but TBH this is just conjecture, I have no proof. It could be, though, that under low oil pressure the oil spray form the front conrod oil hole isn't enough to lubricate the cylinder wall.

I've now started to check compression on every Storm that comes my way, because it seems to be a common problem, and I would like to see if it affects all engines equally, more on those ridden hard or trackday'd or run low on oil, or is just a natural mileage-related wear item.

Won't affect high revs running, or peak horsepower, but makes the bottom end and midrange a bit weaker.
Oh, and borrowing special tool is fine, however I've already reground the pegs as they're not very strong.
It does the job with a little care, though.

[AMCQ46]

Oh, and borrowing special tool is fine, however I've already reground the pegs as they're not very strong.
It does the job with a little care, though.

Thanks Tony, If you post a photo or some dimentions I will try and get one milled out of a socket or something

[oldbikeman]

Vibes as you describe were the exact symptoms of a twisted or out of balance crank on British twins .And they are very similar ,all swinging about on two end bearings.

[AMCQ46]

ok, 1st check done today, when I fought off the hang over and did the compression test.

front 10.75 Bar
rear 10.5 Bar

so that looks both normal and balanced, therefore we can rule that out

was going to balance the carb again, but rather than use the airflow meter [rigged up from a an asthma lung function tester!] that I normally use, I will try conventional vac gauges........Then realised that I need the 5mm adapter for the front cylinder, so that job is stalled as I wait for those bits!.

And I am feeling to crap to try and take the front cam cover off to check the timing, so I think I wil go and watch TV

[AMCQ46]

Right then, I managed to get round to getting teh carbs off, oil cooler out ot the way and took the front cam cover off. so managed to check the front cam timing and valve clearances..........all OK there too

So thats 1 more off the list.......carb balance next but still waiting on the 5mm brass adapter for the front cylinder from carbtune.

I ended up ordering the pack of 4 adapters so I will have 3 spare looking for a new home. will post in the sales & wanted section.

[sirch345]

Keep up the good work AMcQ

It makes a nice change for someone else to be doing the work, but we get to hear the outcome just the same

Good luck in finding the culprit,

Chris.

[AMCQ46]

Well 1st ride out after doing all the other checks confirms the unpleasent truth that they have made no difference to the problem, and the vibration levels on steady throttle are as bad as before, and motorway stints even for 20 mins leave my hands tingling.
So perhaps I now have to consider that I may have the same problem as Pariah and one of the main brg shells has picked up .

Will talk with Roger D next week and see what he says. pariah, what did it cost you to get it fixed?

Not wanting to alarm you too much but if you check all the other things fist and can’t find the answer
check the oil pressure when hot then get back to us if its low

Warby, I guess this is the next test I need to do. Am I right to assume that I would take the oil pressure switch out and fit a gauge into that oilway? Any idea what thread fittings I need to get and what pressure I am looking to measure.

Thanks

[benny hedges]

al. ive found before that on cars, when the crank & shells are fkt, the oil pressure can go up, not down like you would expect.
whats it like when you go up a hill in a high gear & accelerate under high load? does it grumble & rumble through the pegs?
every time ive had a set of mains fail, thats the first thing ive felt / heard.