Ascalon Posted January 18, 2012 Report Share Posted January 18, 2012 Right, over the last six months I have had a fair bit of work done to revive the old 4s. Belts and valves were done, air filter cleaned and re-oiled, new oil and filter and plugs (iridiums) cleaned and gapped correctly. The engine is running sweet as a nut. The forks and shock were rebuilt, new tyres, brake pads, front and rear wheel bearings have now been changed. The headstock bearings were also changed within the last year. Now, I have been getting a high frequency vibration through the bars that I thought I had dialled out by messing about with some SS washers under the bar end weights but this has not really done the trick. Cruising at motorway speeds, it gets pretty intrusive over 100kph. Now as I said, there is a new Roadsmart on the front, pads are well bedded in, bearings are brand new and forks have been rebuilt and dialled in. The vibration seems to be partly engine related as it reduced when you clutch it at speed, but does not entirely go away. I know a big twin is going to be a bit vibey anyways, but the thing is, it wasn't until I got all the engine and suspension work done on it that I noticed the vibes. I have retorqued all fasteners on the headstock and ensured that the forks sit correctly against the bar mounts etc. So, what could it be and what can I do about it? A Link to comment Share on other sites More sharing options...
MonkeyJim Posted January 18, 2012 Report Share Posted January 18, 2012 Take your hands off the bars? Link to comment Share on other sites More sharing options...
buster Posted January 18, 2012 Report Share Posted January 18, 2012 Fill the bars with sand, damps the vibration Link to comment Share on other sites More sharing options...
porter_jamie Posted January 18, 2012 Report Share Posted January 18, 2012 add some mass to the barends, see if that helps Link to comment Share on other sites More sharing options...
BudgetBoy Posted January 18, 2012 Report Share Posted January 18, 2012 Cleaned and lubed chain recently? Something loose (engine mount,bar end etc)go round and check. Wheel bearing? Wheel alignment? Chain/cogs nackered? list is endless tbh.. Link to comment Share on other sites More sharing options...
lorenzo Posted January 18, 2012 Report Share Posted January 18, 2012 Blu-tac in the bars or get rubber mounted wrists. Link to comment Share on other sites More sharing options...
davosaurusrex Posted January 18, 2012 Report Share Posted January 18, 2012 Saw a thread on another forum where a fella melted down some lead (breathe deeply), set it inside a bit of pipe same ID as the bars, hacksawed to length and araldite/epoxy resin'd it to the bar end weights. Reckoned it worked a treat. Link to comment Share on other sites More sharing options...
VanWinkle Posted January 18, 2012 Report Share Posted January 18, 2012 engine mount, bar ends not weighted properly, carbs out of balance. As said, the list can go on. Link to comment Share on other sites More sharing options...
Ascalon Posted January 18, 2012 Author Report Share Posted January 18, 2012 engine mount, bar ends not weighted properly, carbs out of balance. As said, the list can go on. Throttles have been balanced, no effect. Engine mounts have all been retorqued, no effect Exhaust system all checked and retorqued, no effect. Front wheel has been rebalanced after tyre fitting, no effect. Chain has a Scott Oiler and seems OK, have played with the tension on it too, no effect. The bars are solid, so can't be filled. The bar end weights are substantial and as I said, I have had large diameter stainless 1mm thick washers added each side to try to tune it out, but it hasn't got rid of it. The bars themselves are machine from a casting that bolts on top of the headstock. I have retorqued them too, no effect. Anything else I haven't covered? A Link to comment Share on other sites More sharing options...
dansp1 Posted January 19, 2012 Report Share Posted January 19, 2012 First things first, is it related to engine revs?i.e. does it occur at x'000 rpm regardless of gear? if so you are going too slow try a gear lower or change the gearing so it doesn't occur at your chosen cruising speed. Link to comment Share on other sites More sharing options...
Ascalon Posted January 19, 2012 Author Report Share Posted January 19, 2012 First things first, is it related to engine revs?i.e. does it occur at x'000 rpm regardless of gear? if so you are going too slow try a gear lower or change the gearing so it doesn't occur at your chosen cruising speed. There is a natural vibration around 6,100rpm that is a bit intrusive, but this generally occurs outside of my normal cruising range. The bar vibration is noticeable from low speeds, 80kph and upwards but becomes really intrusive between 100 and 120kph. However, it does not entirely go away when going at speed and clutching it and letting the engine revs go to idle. So I suspect that it is some sort of sympathetic vibration, as in the bars responding to a combination of engine speed and road feedback. My plan is, this weekend, to disassemble the front end entirely, right down to the headstock and rebuild everything very carefully to see if there is something awry or misaligned that is causing it. A Link to comment Share on other sites More sharing options...
BudgetBoy Posted January 19, 2012 Report Share Posted January 19, 2012 Well if everything is tight, i would look at anything you have had done since this problem arrived. process of elimination my friend.. Good luck. Link to comment Share on other sites More sharing options...
Ascalon Posted January 20, 2012 Author Report Share Posted January 20, 2012 Well if everything is tight, i would look at anything you have had done since this problem arrived. process of elimination my friend.. Good luck. Well, there's the rub! With a full engine service, full suspension rebuild, new tyres, brakes and generall all round fettling, there's a fuck of a lot of elimination to be done! That said, a trip to the breakers today produced a heavier set of bar end weights that I can adapt to fit, so that may be the ultimate solution. As I was buying a few other bits and bob too, they threw them in for nowt an' all Top blokes CitySpares! A Update: just fitted the new bar end weights, which are about 50% heavier than the OEM ones, and guess what? sorted! I forgot to mention that my Christmas bling was some nice CNC shorty levers, which are lighter than the aftermarket adusjtable one I had, but not by that much. Could that have caused the additional vibes? Fuck knows, but sorted now, as a quick spin up to "cruising speeds" has confirmed. Link to comment Share on other sites More sharing options...
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