Developed a vibration-what to check?

[Midrsv]

My bike suddenly developed a vibration when I roll the throttle on at highway speeds, 60 mph and above. *It started while on a ride last weekend and my wife noticed the vibration from the backrest. Once she pointed it out I noticed it too. My first thought was a problem with carb synch but I synched them right before Vogel and Goose checked them for me while at Vogel. *So I checked them again when I got home and the synch was still perfect. *I also put new caps on the vacuum ports. So now I'm thinking it's an ignition issue. Spark plug, wire or coil. *The plugs only have about 6000 miles on them but I plan to install a new set this weekend. *Is there anything else I can check? *Is there an easy way to check the coils or wires or should I just let the dealer do that?

 

Thanks,

Dennis

[SilvrT]

Tires?

[Squidley]

Dennis,

It has a 5 year warranty...let the dealer look at it if you trust them. I would also check the steering head bearings, I know it sounds dumb, but I have found strange vibrations disappear by tightening the steering head and the swing arm.

[eusa1]

dennis,

 

do you have the chrome carb covers? and did you loosen or remove them when you did the carb adjustments??

[Midrsv]

No, I don't have the covers but I do have them on order.

 

Dennis

[LilBeaver]

I'm with Squidley on this one, let a trusted dealer take a look at it (once you have checked obvious stuff like the bolts on the saddlebags and trunk, and anywhere else you can get to easily for that matter). Vibrations could be anything as simple as that or be something real serious.

[eazyduzzit]

What does it feel like? Is it a high frequency vibration? The reason I ask is because I've developed one too, but mine isn't just when I roll on the throttle, it's just at certain RPMs and I feel it in the grips and when my legs are against the fuel tank.

[Midrsv]

It's definetly engine related. I feel it most in 5th gear and accelerating. Let off the gas and it smooths right out. My wife has ridden a lot of miles with me and she picked up on it with cruise set on about 65 and we started up a grade. She yelled in my ear wanting to know what the problem was.

 

Dennis

[Seaking]

What does it feel like? Is it a high frequency vibration? The reason I ask is because I've developed one too, but mine isn't just when I roll on the throttle, it's just at certain RPMs and I feel it in the grips and when my legs are against the fuel tank.

 

I'll toss in a few coins for this one..

 

Carbs out of sink vibes tend to show up in the mirrors.. if your mirrors show the car behind you as a fuzzy blob, chances are (A) mirror mounts are loose or (B) carbs out of synch. This would also lend to some hand buzzing, making them go numb. Anytime you change anything on the bike, oil, plugs, air filters, clutch even, best to do a carb synch.. Excessive? perhaps.. I'm sure the better techs out there will tell you it's over kill but meh, it only takes a few minutes if you have the kit and you end up with a smoother ride.

 

But in the past, even with a nicely done up carb synch, I ended up with weird vibes. Strangely enough, a fuel filter change quelled one vibe, while a new fuel pump quelled yet another odd vibe..

 

Today I installed a heavy duty clutch and found a lot of my hard to resolve vibes are now gone. I have to ride on rough roads to get a familiar feel to the bike

 

Check your luggage as well.. I had tightened down everything and still couldn't get rid of that one buzz feeling and noise until someone pointed out to put an extra turn on the trunk lid hinges.. and that resolved it.

 

In short, vibes come from anywhere and everywhere, there are the usual culprits, but I've found that just going around tweaking this and that, bolt, screw, nut etc goes a long way..

 

Best of luck!

[Midrsv]

OK, just finished changing the spark plugs and took it out for a ride. I can't say I feel any difference in the vibration under load, moderate acceleration from 60 mph on a slight grade. Attached are photos of the plugs that I took out of it after 6000 miles. I guess I'll contact the dealer next week.

 

Dennis

[Squidley]

The plugs dont look terrible, electrodes are still nice and defined, perhaps the dealer will be the best bet

[jneed53]

65 is, in my opinion, too slow of a speed for 5th gear when accelerating up a grade. Try it in 4th and see if that doesn't do it. I was frustrated with it before realizing the power band is high in these engines.

[V7Goose]

Hope you paid attention to which plugs were which. You clearly have one that is not generating the same level of heat on the ground electrode (the one on the left in your pix). It is firing, but not with the same regularity and power as the other three. My guess is the plug cap has high resistance.

 

Unscrew the cap from the plug wire and measure the resistance; if it is over 12K, you have an easily fixed problem.

Goose

 

As a matter of fact, the more I look at it, the more I wonder if it is even firing at all now.

Same diagnosis, however - check for spark and cap resistance.

Edited August 29, 2009 by V7Goose
Post script

[Midrsv]

Hope you paid attention to which plugs were which. You clearly have one that is not generating the same level of heat on the ground electrode (the one on the left in your pix). It is firing, but not with the same regularity and power as the other three. My guess is the plug cap has high resistance.

 

Unscrew the cap from the plug wire and measure the resistance; if it is over 12K, you have an easily fixed problem.

Goose

 

As a matter of fact, the more I look at it, the more I wonder if it is even firing at all now.

Same diagnosis, however - check for spark and cap resistance.

 

Thanks Goose,

 

I did note the plug positions. I'll check the cap tomorrow. I didn't realize the caps unscrewed. I'll report back after I check it.

 

Dennis