1986 VN750 Vibrates - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 94 (permalink) Old 01-08-2009, 07:54 AM Thread Starter
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1986 VN750 Vibrates

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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post #2 of 94 (permalink) Old 01-08-2009, 08:04 AM
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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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post #3 of 94 (permalink) Old 01-08-2009, 08:55 AM
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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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post #4 of 94 (permalink) Old 01-08-2009, 10:48 PM
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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.

Gordon

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Purchased May 16, 2008
Approx.19,300km (12,000 miles)

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post #5 of 94 (permalink) Old 01-08-2009, 11:01 PM
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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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post #6 of 94 (permalink) Old 01-09-2009, 04:44 AM Thread Starter
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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.
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post #7 of 94 (permalink) Old 01-09-2009, 06:10 AM
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Quote:
Originally Posted by Revelation View Post
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!

Charlie
VN700 project bike 98% completed!!
68 Bushwhacker this winters project (in the works)
86 Honda GL1200i (winter project #2)
82 kz440 daily rider for now!


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post #8 of 94 (permalink) Old 01-09-2009, 06:10 AM
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Quote:
Originally Posted by Revelation View Post
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.


85 VN700 "Old Yella"

REBUILT ENGINE
CUSTOM PAINT
VANCE & HINES CRUZERS
EAR SHAVED AND RE-JETTED W/K&N'S
DUNLOP ELITE K591 FRONT & REAR
VOLTMETER
SYNTHETIC BRAKE FLUID
SYNTHETIC OIL & GEAR LUBE
PLEXISTAR 2 WINDSHIELD
SPLINES LUBED
ACCT'S GREASED W/TOC SPRINGS
COASTERD
LEATHER SADDLE BAGS
LEATHER TOOL AND ROLL BAG
PICKUP COILS GAPPED AT .018"
NGK CAP, WIRES, IRIDUMS
BARNETT FRICTION PLATES & SPRINGS
CUSTOM GRIPS, MIRRORS, LEVERS
ORIGINAL STATOR & R/R 14.5v
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post #9 of 94 (permalink) Old 01-09-2009, 06:15 AM
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O.K Bullwinkle, looks like you beat me to the SUBMIT button. LOL


85 VN700 "Old Yella"

REBUILT ENGINE
CUSTOM PAINT
VANCE & HINES CRUZERS
EAR SHAVED AND RE-JETTED W/K&N'S
DUNLOP ELITE K591 FRONT & REAR
VOLTMETER
SYNTHETIC BRAKE FLUID
SYNTHETIC OIL & GEAR LUBE
PLEXISTAR 2 WINDSHIELD
SPLINES LUBED
ACCT'S GREASED W/TOC SPRINGS
COASTERD
LEATHER SADDLE BAGS
LEATHER TOOL AND ROLL BAG
PICKUP COILS GAPPED AT .018"
NGK CAP, WIRES, IRIDUMS
BARNETT FRICTION PLATES & SPRINGS
CUSTOM GRIPS, MIRRORS, LEVERS
ORIGINAL STATOR & R/R 14.5v
DEKA MF AGM ETX15L

Best Auto/Moto Insurance | Motorcycle Protection Today | FREE Trade-In Quote
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post #10 of 94 (permalink) Old 01-09-2009, 06:31 AM
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Yea but I stopped at the dampers, You have so much more info so, I .
U DA MAN!!

Charlie
VN700 project bike 98% completed!!
68 Bushwhacker this winters project (in the works)
86 Honda GL1200i (winter project #2)
82 kz440 daily rider for now!


A few clowns short of a circus now aren't we?
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