Engine Vibration at 6000 RPM and above

[Ray0hope]

Hi fellow Magna Enthusiasts:
I have a 3 Gen bike, specifically, 2003 VF750. The bike performs great except the engine starts to vibrate at 6000 rpm and above. Granted you're doing 75 - 80 mph with the engine ready for more, but the vibration starts to dampen the ability to sustain higher speeds. My question essentially to my fellow Magna owners is:

Do others have the same experience and is this normal Magna behavior? If not, what may be the problem? There doesn't seem to be any engine power problem as it is ready to hit the red-line and the bike wheels seems to be balanced because once you pull the clutch (engine idling),  the bike is pretty smooth rolling at 90 mph.

I'd welcome any feedback.

[Curtis_Valk]

The '99 I had would start to buzz a little in the foot pegs at about 80 or so, however that never stopped me from reaching 120. LOL  Once you're at redline in 4th, your head vibrates more than the engine anyway.

All that is to say, I think it's normal and I wouldn't worry about it.  The Magna's V-4 is still one of the smoothest around.

Curtis

[dc112675]

I have noticed almost a drone (or vibration) that takes place around 55 mph. Being that I am in 5th gear by then (read: slowpoke) that is just a hair under 4,000 rpm.  But once past that speed it seems to go away.  I would assume I would feel that in other gears, but to be honest I don't always see 4,000 rpm . . . and if I do, it is only for half a second.  

However, you have to remember that most bikes (cruisers at least) red line before that mark.  Really 6,000 rpm is quite a bit.

I have a few tools that generate a good deal of speed (table saw is 3,450 rpm, planer is 10,000 rpm, & dremel tool is 22,000 rpm) yet all of them are relatively small in comparison to the magna's power plant.  At 6,000 rpm that beast is turning 100 revolutions per second.  I would guess it turns several revolutions in the blink of an eye.

I say all of that to say, I think you have to expect some vibration.  Now if your tach falls off or you chip your tooth from the shaking, then yes, you have a problem.

[rjb/AKA Bob Barram]

I have not noticed anything I would describe as a bothersome vibration at any speed or rpm. If it is in fact noticeable I would check the tire balances and air, front rotor.
The 3rd Gen has always ran good even when racing up to the next shift point and running on up the max I have reached with the bike (120).
Bob

[RedMagna]

Do you have a windshield on your bike?  And could this vibration be caused by the wind coming off the windshield and hitting your helmet?

I ride 75 to 85mph for 100 miles a day, five days a week on the interstate and have minimal vibration in the pegs and handlebars, but the wind sheering from my windshield to helmet depends on my body position and can make for a uncomfortable ride if I don't sit properly.

I'd check the wheel balance or see if you have any cupping in the tires that may be causing your problem.

And I can personally testify that riding at much faster speeds than 85mph for long periods of time while on the interstate, my bike still does not vibrate more than expected or to the degree you are experiencing...  Now if you have a passenger, they may not think so but...  

[merrow]

I have a '99.  I try to keep it under 5000 because the cops have already warned me the speed limit is 60 on the way to work and my gas mileage starts to go down hill after that.  I am not always sucessful.  The only way I know I have gone over and hit 85 or 90 is to look at my speedometer.  I have had it up to 100 and the bike was so smooth I would not have known I was going that fast except for the speedo and I was aware of covering a lot of ground in a very small amount of time.

[trapper]

Do you have a windshield on your bike?  And could this vibration be caused by the wind coming off the windshield and hitting your helmet?

It also be turbulence from air coming UNDER the windshield; I mean if you have a windshield....

[seratt]

Hi Ray,

I have a similar problem also on my 96' Magna.  My vibration starts right around 5500 rpm and goes away around 5800.

Below 5500 and above 5800, she's smooth as can be.  It's something I've been told to not really worry about.  Doesn't matter what gear I'm in, she just likes to vibrate at those revs.

I'm pretty used to it now.  Even though at 75mph she's at 5500, I just tune out the vibration now.

Tim

[Charles S Otwell]

Just do like Bob, Jimmy and Jeff and don't ever drop below 5000 rpms  

[Slydynbye]

I've always noticed that vibration on a 4 cyclinder can be from a few things.
1 Carb synch or clogged jets on a carb
2 fouled plug
3 need of valve adjustment (which is least likely for a magna but possible).

What's the track record of this bike?

Ridden seldom with a lot of garage time = possible bad gas and clogged jets.

Ridden at low RPMs and a lot of choke needed to start= fouled plugs

High mileage and never had the valves adjusted?

Are you a wheelie popper or drag racer with the habit of dumping the clutch?
You could have a cam chain problem in your future.

[Ray0hope]

Hi all,

Thanks to all for the feedback on the engine vibration. It was very informative. Here are some more facts around my Bike to help answer some of the questions:
 
* The bike has 7000 miles and is ridden only during the summer (5 - 6 months). Average trip is around 50 miles.
* The engine oil and filter has been replaced every 2,000 miles or at least at the end of the season. Only OEM filter and Honda spec oil has been used.
* The spark plugs have been replaced and the carbs have been sync'd.
* The engine runs pretty tight, no back fire, idles smooth and sounds like it did once it left the dealer 4 years ago.  
* The tires are in good shape and the wheels are balanced. The bike rolls pretty smooth at 80 - 100 mph.
* There is a windshield on the bike but has had no impact on the vibration felt at high speed/engine RPM.
* The bike is essentially stock with no modifications to engine, exhaust, suspension etc.
* The vibration/buzzing behavior is very consistent i.e. it starts at 6000 rpm and stays the same all the way to the redline.

Hope the above will help clarify my situation and confirm if there is a problem with my bike or if this is normal Magna behavior.

Again, Thank You all for sharing your experiences.

Ray










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[Slydynbye]

It sounds like you are hearing and feeling the engine come into it's power range.
I believe the Magna has 2 sides, the mild side below 4k and the wilder side above 5K when the revs create power. Mine is not jetted or shimmed so I get a pronounced change in power and sound at 4-5K.

[RedMagna]

Hi all,

* The bike has 7000 miles and is ridden only during the summer (5 - 6 months). Average trip is around 50 miles.

Hmm, I think you just need to sell the bike to me if it's got that low mileage on it and if you're not going to ride it more than that.  

I cannot think of any other reason than all the great suggestions people have made here already.  I've felt vibration at 70mph on a Rebel 450 for prolonged periods of time, but never to how your saying on my Magna.  If you can hook up with one of the MOOT events, let them take a look and ask them to ride the bike to see if it's abnormal.

[silveradocowboy]

Just do like Bob, Jimmy and Jeff and don't ever drop below 5000 rpms  

HEY ... I resemble that remark!    At least you didn't call me a runt.