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Discussion Starter · #1 ·
How do,

I've got a bit of a problem which I'm hoping someone may be able to help with.

My GL500 has developed quite a bad vibration, especially noticeable over 5000rpm. I know these bikes are known for being a bit bad on vibration but it's never bothered me in the 9000 mile or so I've done on it, but this is new and bad enough to give me pins and needles in my feet!



Since I noticed it I've adjusted the tappets (which has made it a lot quieter) but not affected the vibration. I thought it could be unbalanced carbs but without a carb balancer I can't tell for sure, but I can turn the idle down to 200-300rpm and the engine still runs fine which from what I've read suggests that they are well balanced. I've also checked all the engine mounts and they are all tight.



Next step is to pull the carbs and check that they are unblocked. I pulled the float bowls a while ago and then fitted an inline fuel filter but I suppose there could have been some stuff still in them. (There was a load of rust that had come through from the tank having been stood for ages)

I also need to change the spark plugs as well.

Anything else that I should be checking? Am I on the right track with searching for the cause of the vibration?

Hopefully I'll get it sorted as it's beautiful riding weather here!

Thanks in advance for the help,

Jof
 

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Out of balance carbs can cause vibration, as can numerous other things. Is the vibration linked to engine speed? Could be caused by a weak spark on one side. Low compression on one side etc. If not linked to engine speed (ie try pulling your clutch in and coasting) could be a wheel out of balance, bad tire etc.



You can make a carb balancing tool with some vinyl tubing, a couple of clear bottles and some rubber stoppers. Here is the idea...The clear tubes get attached to the ports on your intake manifolds. Fluid will be drawn into the bottle that is connected to the side with more vacuum. The carbs are in balance when no fluid is being drawn into either bottle from the other. No fluid can be drawn into the engine with this setup. I made a set of these using Snapple bottles and black rubber stoppers from True Value. This is a pic from a post on the netrider forum.

 

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Discussion Starter · #3 ·
Thanks for the reply. The vibration is definitely linked to engine speed as I've pulled the clutch and coasted and it cleared up straight away. I've also noticed that I've got to rev slightly higher to maintain the same speed than I was doing before the vibration started. I used to be able to do 70mph at 6000rpm but that has gone up to closer to 6500rpm.

I couldn't see the picture in the reply but I'll get some tubing and see what I can sort out.
 

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I would go for carb balancing.You can make your own but if you have money by far the best one made IMHO is the one I and others on here use e.g the Carbtune2,



http://www.carbtune.co.uk/carbcust5.html



http://www.carbtune.co.uk/carbdtls.html



It is a none mercury serviceable unit which is very very easy to use,ships fast to anywhere in the World.You can recoup cost by doing other bikes if you like.Most bike shops will charge anything from 75 beer tokens upwards for a dual carb bike but get the 4 cylinder version as it's not much more than the two cylinder version.
 

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The RPM difference bothers me, almost as if the clutch is slightly slipping. Has anyone accidentally put some of that energy saving oil in the crankcase as some time? If so, your crankcase will need a good flush with something like kerosene and a fresh refill of the proper oil such as Shell Rotella 15W40 which is a good idea to do anyway, a periodic flush can be helpful in getting sludge out that fresh oil by itself won't tackle.
 
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