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Discussion Starter #1
Just bought a 1986 VN750. It vibrates on takeoff and through the gear changes. Took it to a mechanic and he said it's not the motor, maybe the engine mounts. Can anyone help if they had similar problem. I am new to this sort of bike, so any input would be great.
 

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Premium Member
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Welcome to the forums. It could be the mounting bolts, some folks have had them loosen and fall out, some have tightened them to stop vibrations.

Could be out of balance wheels, bent rims, or bad tires.

Could be the engine, even though a mech. says otherwise.

I'd look at it real good first, bent rims, wheel weights etc. And take a wrench to all the nuts and bolts a the same time, make sure it's all tight.

Do you know any history of the bike, like was it crashed or something?
 

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and the Adventure Cycle
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Check the oil (using the side drain with the screen in it, not the bottom of the engine drain) for any bits of rubber. Like Doug mentioned, could be the engine....... balancers going bad.
 

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Linkmeister Supreme
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Do you have any vibration from the engine at higher rpms when the bike is not moving. Just trying to eliminate the engine as a source of the bad vibs.
 

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Love My Baby
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My baby was vibrating quite noticeably. All it was, was the handlebars needed to be tightened to the proper torque (17.5 ft-lb). Four bolts on the handlebar clamp under the plastic cover tabs.
 

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Discussion Starter #6
Thanks for that info. Pulled out the long filter and found it to be ripped around the edges. Need to get a new one. There were some black spots, like dryed oil. I don't find any metal pieces anywhere after draining the oil and checking everything out. I am going to get the bike completely checked out though because of its age. This is a great forum and thanks to all who took the time to answer my question. I'm sure as time goes on I will have some more questions.
 

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Addicted to Projects
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Thanks for that info. Pulled out the long filter and found it to be ripped around the edges. Need to get a new one. There were some black spots, like dryed oil. I don't find any metal pieces anywhere after draining the oil and checking everything out. I am going to get the bike completely checked out though because of its age. This is a great forum and thanks to all who took the time to answer my question. I'm sure as time goes on I will have some more questions.
By the long filter I assume you mean the filter screen from the side oil drain? If so examine the items you are finding on the screen. If they are hard, dark and kind of rubbery assume they are the balancer dampers. They tend to get hard and deteriorate if the bike has sat for any length of time. If they go, the balancer will "wiggle" around on the pins it rides on and eventually loosen the bolt holding it to the shaft, dropping down and begin to eat away at the crank case. Pull the oil filter off also and check for chunks of rubber.
Been there, done that, got that Tee shirt!
 

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The Professor
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Thanks for that info. Pulled out the long filter and found it to be ripped around the edges. Need to get a new one. There were some black spots, like dryed oil. I don't find any metal pieces anywhere after draining the oil and checking everything out. I am going to get the bike completely checked out though because of its age. This is a great forum and thanks to all who took the time to answer my question. I'm sure as time goes on I will have some more questions.
What you are looking for are pieces of hardend rubber. When the counter balance dampeners go bad the become hard and brittle, then disintegrate. Some tiny specs of dibris will be normal, as the clutch friction disc wear down.

As far as the vibration as others have stated, check the following:

With the bike on the center stand sitting on the bike with feet on the pegs, rev the engine to check for engine vibration at hands an feet. The carbs. may need te be cleaned and syncronized.

Tighten all mount bolts.

Check your air filters.

Check your plugs.

Do a compression test, if you have more than a 10psi variance one cylinder will pull harder and cause a vibration under load.

If your sure the engine is not the problem???

Have tires and rims checked for balance and straightness.

Check driveshaft univesal joint and splines.

Check axle tightness, front and rear.

Check wheel bearings by wiggling the wheel from side to side.

Check handle bar clamp.

Check the steering head bearings and spanner nuts.

Check the swing arm for side to side play.

I know it is a lot to check but it all needs to be checked anyway for safe opperation.

But first answer this question:
Does the vibration start immediatly upon acceleration and continue through all gears untill cruising speed, and then stop at cruising speed or decceleraton or continue?

This will help isolate the problem. :beerchug:
 

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The Professor
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O.K Bullwinkle, looks like you beat me to the SUBMIT button. LOL :beerchug:
 

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Addicted to Projects
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Yea but I stopped at the dampers, You have so much more info so, I
.
U DA MAN!!
 

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Discussion Starter #11
Nothing much on the oil screen

The oil screen had some stuff on it but nothing I would get alarmed about. Some very small bits of debris thats all. I checked the oil and oil filter and couldn't see anything that would worry me. I am starting to think the vibration has more to do with the engine mounts. I am going to get the bike checked out so I am sure whatever is causing it will come to light.

Even with the vibration, I love the bike, it is very easy to ride and has lots of power. Where-ever I go people look at it and it does look good. I bought the bike because I liked it and will restore it to its full glory. It will probably be my last bike before I kick off from this planet.
 

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The Professor
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The oil screen had some stuff on it but nothing I would get alarmed about. Some very small bits of debris thats all. I checked the oil and oil filter and couldn't see anything that would worry me. I am starting to think the vibration has more to do with the engine mounts. I am going to get the bike checked out so I am sure whatever is causing it will come to light.

Even with the vibration, I love the bike, it is very easy to ride and has lots of power. Where-ever I go people look at it and it does look good. I bought the bike because I liked it and will restore it to its full glory. It will probably be my last bike before I kick off from this planet.
Where do you live? maybe a member can tell you a good place to take it to in your area, without getting screwed. :doh:
 

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Premium Member
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We do have another regular member here in Australia, but I have no idea where he lives there, or if it's near you, and right now I can't even remember his screen name....****.
 

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Linkmeister Supreme
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The oil screen had some stuff on it but nothing I would get alarmed about. Some very small bits of debris thats all. I checked the oil and oil filter and couldn't see anything that would worry me. I am starting to think the vibration has more to do with the engine mounts. I am going to get the bike checked out so I am sure whatever is causing it will come to light.

Even with the vibration, I love the bike, it is very easy to ride and has lots of power. Where-ever I go people look at it and it does look good. I bought the bike because I liked it and will restore it to its full glory. It will probably be my last bike before I kick off from this planet.
So just how old are you Rev? There are quite a bunch of us here like me, in our mid 50`s, some 60`s and FlaRider, another newbie here, is "pushing 70", his words, not mine. One member mentioned a friend who is 90+ and still riding a trike. Who knows, maybe there is one of those still in your future! :smiley_th

You`re right about the bike, it does have plenty of power and does draw looks where ever I go too.
 

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Linkmeister Supreme
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We do have another regular member here in Australia, but I have no idea where he lives there, or if it's near you, and right now I can't even remember his screen name....****.
Campadres Carl is in Sydney, N.S.W., so he`s as much your neighbor as I am to the guys in Tennesee or Texas. He`s a member of a Christian motor cycle club called the Compadres. He`s also a mechanic or autobody man and can probably help you find any good online bike sources there on your BIG Island. <BG>
 

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Discussion Starter #18
I'm 55. I find the VN750 a great bike to ride. Tried one of those sport bikes that can do 300 kms an hour, laying on the petrol tank with legs back wasn't my cup of tea. My legs cramped up after a few seconds.
 

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Addicted to Projects
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Hope it is the motor mounts! They are much easier to replace than the dampers. If there is anything we can do let us know! Got pictures?
 

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Discussion Starter #20
The vibration starts on takeoff and right through all the gears. There is a slight vibration at crusing speed and decceleraton. Today I was cruising on 110 km and the motor completely cut out. I was out in the country side and I thought I was stuffed. But after a few attempts it started. I rolled it down a hill to get it started. I just bought the bike a few days ago and I think the bike has been sitting for months without being used and that probably has something to do with some of the problems I am encounting. I bought the bike as a work in progress so nothing will surprise me. It was a good buy (no dents, rust and not many scratches) because it looks great cosmetically for its age and actually runs remarkable well for its 23 years. I looked at other Vn750s the same age and they looked shocking and those people wanted a lot more than I paid for mine. So if I have to spend some time and money on the bike, I have already factored that in.
 
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