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Discussion Starter #1
I've had my 2005 Spirit 1100 for almost a year now, and have nearly 10K miles on it. Over the last few days I've noticed something when accelerating through 2nd gear I'd never felt before -- the vibration I feel through the grips changes at about 45mph or so. It becomes "sharper," more pronounced and quite noticeable. (It's hard to describe.) If I shift to 3rd it goes away. I think it goes away if I continue to accelerate in 2nd -- meaning it might occur only in a specified band of RPM (I'd have to take the bike out and verify this.)

By the way, this is after the bike is fully warmed up.

It's utterly foreign to me after 10K miles of experience with this bike.

Note: this is not the rev limiter. I know what that feels like, and this is not that.

This appears to be a 2nd gear phenomenon only ... I revved out 1st gear earlier today and did not experience this. I could consistently recreate in 2nd. 3rd, 4th and 5th operate as I've come to expect. The bike seems to operate just fine otherwise.

Differences that might be contributing:

o It's colder here than when I normally ride ... low to mid 40's.
o I've been running 89 octane gas

Anyone care to put on their diagnostic hats and speculate on this? I realize a precise diagnosis is difficult. But speculation is fun.

My 1 year warranty expires at the end of January. :(
 

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I wonder if there is a point in there where the engine RPM and the tire RPM are matched... I mean, one is exactly double or triple the other... and the vibrations from each are amplifying each other. Shifting drops the engine RPM and the match isn't there any more. I would look at my tires first, just because you don't have to take anything apart to check them. Litnin or someone else with a engineering mindset plus technical knowledge may be able to do the math and see if there is such a match point in high RPM second gear. (Or I could be nuts... that's been known to be true in the past) :D

EDIT: Does second gear have any other recent quirks? Hard shifting? Jumping to Neutral? Possible wear from jumping to Neutral frequently when the bike was new to you? I know I sure missed second a lot when I was a beginner, always wondered if that would haunt me later.
 

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Discussion Starter #3
Trueseaker said:
Does second gear have any other recent quirks? Hard shifting? Jumping to Neutral? Possible wear from jumping to Neutral frequently when the bike was new to you?
Good question ... but no, it's pretty normal. There's the usual "ker-chunk-thunk" moving from 1st to 2nd, but it's nothing out of the ordinary. I've never missed 2nd.
 

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It might be good to go over ALL of the engine mounting bolts and make sure they are tight.

Also, if your not accelerating at that speed in that gear then your not calling up extra power and its time to shift. Under load (demanding power) either to pass, pull a steep hill, or just an adrenaline rush ect.... then 45mph is okay.

The engine under a higher RPM REV (45mph second gear) and no load, no real toruqe is being applied, the engine will feel much different than it does under a load.

Someone will probably want to correct me on this, but a free reving engine will blow at a lower RPM than the same engine at the same RPM's under a load.

So 45mph in second gear is fine if your in need of power, but for just rolling down the road then 45mph in second gear is at the top end of the gear (RPM range) for a normal shift, I Don't Mean Red Line, but I do mean its at a high enough RPM to be time to shift.

And yes! engines like the ones used on our Shadow's can FEEL MUCH different in extreme climate changes, or even altitudes.

The more modern automobiles and their fancy computers, that are working right, are always adjusting things, like timing, air fuel mixture, for things like abient tempareture, altitudes, extra damp, or extra dry. So in cars you don't feel these defferences as much as you do on your motorcycle, these bikes don't have computer systems that complex, so they are more sensitive to climate changes and yes, enough to feel.
MarkC
 

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Discussion Starter #5
MarkC said:
It might be good to go over ALL of the engine mounting bolts and make sure they are tight.
I'll do that ... if I can find them. :oops: Still, it'll be a good learning exercise for me to get on my hands-and-kneeds and hunt for them.

The new vibration is occurring "under load" in the sense that I am accelerating at the time the vibration "changes" to this new variant. So it's not the case that I'm crusing down the interstate at 50 or so in 2nd gear.

MarkC said:
And yes! engines like the ones used on our Shadow's can FEEL MUCH different in extreme climate changes, or even altitudes.
It may be that. Or it may be that my imagination is getting the better of me. It could be that it's occurred before, but I didn't notice it or for some reason I'm just hammering the throttle more in the past few days than I normally do. If I accelerate up through the gears "normally" then the bike behaves as I'd expect.

I took it out a little while ago and was cruising quite normally at 85mph indicated in 5th gear on flat interstate. No excessive vibration or anything that felt different from normal.

MarkC said:
The more modern automobiles and their fancy computers, that are working right, are always adjusting things, like timing, air fuel mixture, for things like abient tempareture, altitudes, extra damp, or extra dry.
What?!!! Are you telling me my Shadow Spirit isn't a super high-tech space-aged computer controlled beast of a motorcycle? :)

If I were to guess I'd say it's a combination of the cold, damp air here (somewhat unusual for Tucson, even in the winter), my being a bit more aggressive lately (for the fun of it) and my noticing something slightly different and allowing my imagination to get the better of my good sense.

Still, I'll check the engine mount bolts. And I'll give the front tire a good inspection. It has 10K miles on it. I recently changed out the rear tire.
 

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Well, let me put my 2 cents in here Tucson.

What I think it "might" be, is that at the speed/gear you mentioned (45mph) your MAY be on the cusp of the main jet circuit in the carbs. Just imagine that you throttle past it in the climbing "rpm's" but the hand relaxed a little and now it's back off the main jet/s. This on/off transition MIGHT cause a "stutter/vibration" felt in your NOW experienced hands/butt!!!! :shock: :shock: Plus add to this factor...maybe the carb sync might be off "just" a little (a little more stutter/vibs) and then add the other factors of cool/cold temps, thick oil, low air pressures in tires BUT the operator is very senstive to HIS new found friend! :wink:

Yes, one can get the engine speed/bike speed to a "certain" rpm and get many types of harmonic vibrations. Maybe you found one of those areas on your bike! 8) :wink:

Bullzeyet
 

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Discussion Starter #7
bullzeyet said:
Yes, one can get the engine speed/bike speed to a "certain" rpm and get many types of harmonic vibrations. Maybe you found one of those areas on your bike! 8) :wink:
I had no idea all those things can come together to create different harmonic vibrations. Fascinating stuff. All way over my head, but fascinating just the same. I'll keep an eye on things and see what happens.

But from what I'm gathering from you and MarkC and Trueseaker, this doesn't raise an obvious red flag of warning.
 

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When I read your original post I immediately wanted to ask when you last sync'd carbs and changed plugs. But then it was coverd by Barry. MarkC's suggestion to check engine mounts was also a great idea.

Those should be good starting points that are cheap to fix/check.
 

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Discussion Starter #9
cbjr0256 said:
When I read your original post I immediately wanted to ask when you last sync'd carbs and changed plugs.
Well, I'm not very good when it comes to wrenching my bike. I'm pretty good at swiping my credit card at the dealer, though. My bike has 10K miles on it now, and during that time I've taken it in for the 600, 4K and 8K checkups. To the best of my knowledge the carbs have never been synched. The plugs were changed at 8K (they looked fine; no carbon buildup or anything). The engine idle was adjusted at 8K as well -- down I think, but I can't recall.

I don't remember the dealer mechanic mentioning anything about carbs during all that time. (And the dealer I work with seems pretty straight-up; no reason yet to be really suspicious of them.)
 

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I've got my bike away for the winter now, but I was experiencing something similar to you last fall. My windshield is mounted rather close to the speedometer, and at certain speeds in gears, I noticed a buzzing sound from the speedometer and it turned out to be the speedometer vibrating against the windshield caused by engine vibrations. It wasn't limited to second gear for me though. In each gear, there was a certain rpm range where the vibration and buzzing occurred, and if I backed off the throttle or accelereted past it, the vibration and buzzing stopped.
I'll probably look into it next spring when I get to ride again.
 
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