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Post by professore on Sept 1, 2010 13:14:12 GMT -5
Hi,
I get a lot of vibration at speed (70 mph +). Any ideas what might cause it?
Thanks,
Bob
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Post by Jake on Sept 1, 2010 15:28:44 GMT -5
Hi, I get a lot of vibration at speed (70 mph +). Any ideas what might cause it? Thanks, Bob Hi Bob.... Vibes could be caused by a number of things. Wheels out of balance. Worn tyres or wrong tyre pressures. Worn headstock bearings. Loose bar end weights. Suspension settings e.g. old fork oil etc…. Knackered exhaust silencer. Or, maybe the engine needs tuning i.e. carbs and valves adjusted. |
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Post by professore on Sept 2, 2010 5:31:40 GMT -5
Thanks ! I should add that the vibration seems confined to the footpegs - and seems to start around 5 K rpm at any speed - even when bike is stationary - so would suggest a valve clearance - carb balancing problem - or maybe loose footpegs  Wheels out of balance. Possible ;DWorn tyres or wrong tyre pressures. Checked tyre pressures this morning. Both a bit soft. That's now sorted Worn headstock bearings. I think they're OK as steering moves smoothly with no notchiness.Loose bar end weights. Hmmm they seem ok Suspension settings e.g. old fork oil etc…. did fork oil and seals and think all is OK as had the help of an experienced bike mechanic. Will ask him at the weekendKnackered exhaust silencer. Or, maybe the engine needs tuning i.e. carbs and valves adjusted. - probably the cause .... haven't got round to doing them. Engine seems a bit unwilling as well so probably the issue. Some fun for the weekend ! |
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Post by professore on Sept 6, 2010 2:57:39 GMT -5
Ok had a good look over the weekend. I almost did the valve clearances - but thought I had rounded off the crankcase cover bolt so put everything back together only to discover I just hadn't shoved the allen key in far enough - d'oh !!!. Anyway will know for next weekend.
Anyway, I found that the bolt that attaches the exhaust pipe - I have the stubby one on my '93 German imported Revere 650 - was missing a nut and washer !!! Went to the local hardware shop and got some and hey presto, problem solved.
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Post by Jake on Sept 6, 2010 3:42:33 GMT -5
Anyway, I found that the bolt that attaches the exhaust pipe - I have the stubby one on my '93 German imported Revere 650 - was missing a nut and washer !!! Went to the local hardware shop and got some and hey presto, problem solved. Oops....  Has this solved the vibration problem? |
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Post by professore on Sept 6, 2010 4:31:16 GMT -5
Pretty sure vibration problem solved ... didn't get a chance yet to really take an extended high speed blast as it's very wet here right now but did do a few high rev blasts from the lights which normally have the same effect and seemed fine.
Will keep you posted if problem is not gone.
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Post by professore on Sept 21, 2010 5:40:14 GMT -5
Ok I can now confirm that my footpeg vibrations are less, but still more than what I think they should be. I haven't done carbs yet, but idle is very smooth and plenty of power especially after doing the valve clearances. I also have to check the engine mounting bolts. BTW where are they - are 2 of them part of the engine guard ?
Is it possible that a loose exhaust baffle might cause this - as I still have the stock stubby exhaust + collector box and it has seen better days (although doesn't appear to have any leaks) ?
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Post by professore on Sept 21, 2010 5:42:21 GMT -5
Maybe I'm being too picky .... what kind of vibrations do other people get - does it kick in around 4 K revs and steadily get worse - and is there more in one footpeg than the other ?
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Post by Jake on Sept 21, 2010 7:18:20 GMT -5
Maybe I'm being too picky .... what kind of vibrations do other people get - does it kick in around 4 K revs and steadily get worse - and is there more in one footpeg than the other ? Having experianced vibes on the CX500 (recently sold) I kind of expected some vibes when I bought the NTV....  For a start the previous owner had fitted a Laser exhaust can which wasn’t road legal and made a lot of noise (including backfiring on the over run) so I changed it to a Motad which calmed things down a bit. I found the NTV footpegs a bit small compared to the CX’s so I fitted some after-market alloy-pegs, wrapped them with duct tape and cut down some handlebar grips to go over them. It sounds messy but it's a tidy job.  I also fitted some thicker grips on the handlebars themselves, together with a Vista Cruise control and heavier bar end weights which I got from Busters... Finally I bought some 50mm bar risers which also helped kill some of the handlebar vibes and made the riding position more comfortable. Engine now feels smoother with Silkolene 5w40 fully synthetic oil. But the only thing I haven’t checked yet, is the engine bolts. |
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Post by professore on Sept 26, 2010 4:17:14 GMT -5
Hi Bob.... Vibes could be caused by a number of things. Wheels out of balance. Worn tyres or wrong tyre pressures. Worn headstock bearings. Loose bar end weights. Suspension settings e.g. old fork oil etc…. Knackered exhaust silencer.Or, maybe the engine needs tuning i.e. carbs and valves adjusted. I have found the problem, the stubby exhaust has a cylindrical bulge in the middle which apparently indicates it's rotting from the inside. Can anyone suggest a cheaper alternative than replacing it ... I don't fancy spending the best part of € 200 for a new one. |
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Post by Jake on Sept 26, 2010 10:15:56 GMT -5
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Post by professore on Oct 16, 2010 4:48:58 GMT -5
Bought a stainless steel Motad exhaust - has done the trick and no more "phut phut" on deceleration. Also have since done valve clearances (one or two needed adjusting) checked carb balance (was spot on already).
Also got a new front tyre as discovered old one had a leaky valve and was going soft.
All of the above have made a big difference, but the exhaust the biggest difference.
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