Acceleration vibration

[Patrick]

Anyone ever experienced a vibration only during acceleration in top gear ?? What was the problem ??

[sandy]

Start looking at your drive train. Maybe U joint.

[Chrisj CMA]

Anyone ever experienced a vibration only during acceleration in top gear ?? What was the problem ??

Well, if you were doing say around 35mph and rolled on the gas hard.....just because the phat girl will do that without complaining doesnt mean its real good.  until you get into the power band for that gear there usually will be a growl or minor vibration at lower speeds.  If that is what happened then to answer your question.....there is no problem.  If there is vibration at any speed while in 5th gear acceleration and it doesnt settle down then I agree pull the drive train and look at the pinion cup and the u-joint

[Michvalk]

Carb sync can cause a buzzy vibration in the bars under load as well. But look to the drivetrain as well

[Ricky-D]

In a perfect world with that feeling (vibration) you can say it is the motor's compression and firing strokes that you feel (and hear).

But in your case (which is normal) most of the vibration and noise is because of all the drive train tolerances, that loosen up with miles, and are now making themselves more noticeable.

You can attend to to some of them by having a good universal joint, drive shaft and pinion cup, good fitting drive flange, and well fitting dampers in the wheel.

But you cannot rid yourself of all what you experience because some of the noise and vibration is within the transmission and connecting gears in the motor.

You can ride the bike to aggravate the situation and make it progressively worse or you can ride the bike avoiding that (which you report) and producing less wear and tear upon the bike. It's all (in) how you ride the bike.

***

[jmann]

In a perfect world with that feeling (vibration) you can say it is the motor's compression and firing strokes that you feel (and hear).

But in your case (which is normal) most of the vibration and noise is because of all the drive train tolerances, that loosen up with miles, and are now making themselves more noticeable.

You can attend to to some of them by having a good universal joint, drive shaft and pinion cup, good fitting drive flange, and well fitting dampers in the wheel.

But you cannot rid yourself of all what you experience because some of the noise and vibration is within the transmission and connecting gears in the motor.

You can ride the bike to aggravate the situation and make it progressively worse or you can ride the bike avoiding that (which you report) and producing less wear and tear upon the bike. It's all (in) how you ride the bike.

***

+1 what he said. 

[BonS]

Anyone ever experienced a vibration only during acceleration in top gear ?? What was the problem ??

Odd thing, I just had it happen today. Had my girl for 13 years and never felt anything like it. We were traveling on a relatively flat road, around 60 mph, and backed off the gas (quickly) when a truck entered the highway. As the truck accelerated I did too and that's when I felt it. I did a quick check of my rpm's as it "felt' like lugging but no way! This was something else. The harder the acceleration the worse the vibration. I backed off the gas and carefully felt things out and each time I'd accelerate it was there. I admit I was thinking ujoint. I knew I was near a good stopping place in a couple of miles so I eased off the gas and slowed down a bit and kept riding and listening to see if I could figure it out. There wasn't any noise associated with the shuddering. My u-joint is fine. I had just completely serviced the rear end when installing new rubber and everything is perfect. After riding a couple of miles I again tested the problem with some acceleration and the vibration/shudder is completely gone. I continued my trip for another 80+ miles and everything is running perfectly again.

My best guess is that some particle in the gas found its way into a carburetor and was stuck somewhere causing a too rich condition. If it was too lean I sure didn't hear any pinging of pre-ignition. When the cylinder cleared the problem disappeared.

I have another 1,000+ miles on this trip and if it comes back I'll report on it.

[Patrick]

Thanks to those with the serious responses.. I had to grin at the comical ones.. The rest of the story.. For those that read most of the earlier posts, When I went to reinstall all of the STUff after I decided to do the rear maintenance[due to valve stems] because of the drive shaft /u-joint issue I installed the swing arm, u-joint and drive shaft together, then shoved in the rear drive.. The only 'out of the ordinary' thing was to remove the pinion cup to check how drive oil got into and out of the cup concerning a post that was going on at the time.. Now, I just took off as little as possible to get at the u-joint and pushed it back several times against the spring pressure just to be sure the shaft was fully in the drive cup.. I loosen the 4 drive retainers and axle retainer.. Tightened axle and drive retainers,, worked u-joint back a couple more times.. The only other things was to add an extra turn on the shocks [440s].. All seems much more better..

[Tx Bohemian]

Thanks to those with the serious responses.. I had to grin at the comical ones..

? ? ?  "comical ones"

Are there more posts to this somewhere??  Or did I just miss the "comical ones"? 

I'll admit if the posts get too long winded I'll just glance over them and maybe not read everything.

[Hoser]

Thanks to those with the serious responses.. I had to grin at the comical ones.. The rest of the story.. For those that read most of the earlier posts, When I went to reinstall all of the STUff after I decided to do the rear maintenance[due to valve stems] because of the drive shaft /u-joint issue I installed the swing arm, u-joint and drive shaft together, then shoved in the rear drive.. The only 'out of the ordinary' thing was to remove the pinion cup to check how drive oil got into and out of the cup concerning a post that was going on at the time.. Now, I just took off as little as possible to get at the u-joint and pushed it back several times against the spring pressure just to be sure the shaft was fully in the drive cup.. I loosen the 4 drive retainers and axle retainer.. Tightened axle and drive retainers,, worked u-joint back a couple more times.. The only other things was to add an extra turn on the shocks [440s].. All seems much more better..

Did you remember to tighten the 4 bolts that hold the drive shaft cover to the pumpkin last?  This is important , that is what aligns the gear set.  I see you loosened and retightend it, that should fix it.   Hoser

[R J]

I had that type of a vibration about 9 years ago.

I was running stock tires and the rear was severely cupped.

Replaced the tire with a Darkside and it has never returned.

Also, the DS does not cup, anyway, none of mine have.

If memory serves me correctly, I'm on # 8 DS tire.

[Madmike]

any chance it was a miss??

[Patrick]

It sure doesn't seem like an engine mis-fire.. Its a hard high-pitched mechanical vibration felt thru the bars and pegs.. I haven't really done anything different than in the past regarding maintenance procedures except for installing the drive shaft prior to the rear drive and removing the pinion cup to see how it is lubed.. Its not there in any gear except 5th and its as smooth as always at cruise.. And, I do tighten the axle retainer then the drive retainers..

[Ricky-D]

Maybe the pinion cup is becoming loose!

***

[Chrisj CMA]

It sure doesn't seem like an engine mis-fire.. Its a hard high-pitched mechanical vibration felt thru the bars and pegs.. I haven't really done anything different than in the past regarding maintenance procedures except for installing the drive shaft prior to the rear drive and removing the pinion cup to see how it is lubed.. Its not there in any gear except 5th and its as smooth as always at cruise.. And, I do tighten the axle retainer then the drive retainers..

Well two things......

1.  You can peek behind the boot to see if there is anything obviously wrong with the u-joint

2.  One good reason to NOT instal the drive shaft seperately from the drive is, you cannot be sure you didnt buggar up the oil seal that goes into the pinion cup.  If that happened....well you can figure that part out

[Patrick]

Well, I did pull the boot loose and work the u-joint against its spring to help make sure the shaft was seated.. When I first installed the rear drive, I didn't think about the shaft seal[ brain fart].. I sure don't want to take this monster apart again,, this was all over a couple valve stems..

[Chrisj CMA]

Well, I did pull the boot loose and work the u-joint against its spring to help make sure the shaft was seated.. When I first installed the rear drive, I didn't think about the shaft seal[ brain fart].. I sure don't want to take this monster apart again,, this was all over a couple valve stems..

Ya, I know.....but if you truly have drive train vibration.......I have the gift of interpretation here.......its saying fix me now cheap.....or get stranded and pay big bucks later........if its a u-joing a pinion cup or dampners (probably culprets) they are easy and not so expensive to fix...........have the thing crap out on you and it will ruin your trip, your day, and your wallet

[Patrick]

Kinda like the old Fram filter ad, huh.. I've been meaning to order some spare parts before they become unavailable,, so,, I did today.. The drive shaft seal was among them,, so,, it'll probably come back apart pretty soon.. None of the hard[ or semi-hard  ] parts are bad or they would have been changed last week..  I think I'll put it together this time with zippers or velcro..

[Ricky-D]

That drive shaft seal is pretty inconsequential and has nothing to do with your particular query,,, whether or not it is positioned correctly!

***

[Chrisj CMA]

That drive shaft seal is pretty inconsequential and has nothing to do with your particular query whether or not it is positioned correctly!

***

but if its pushed off its perch than oil isint maintained in the cup and contaminates can get in there and cause rust and wear over time

[Ricky-D]

That drive shaft seal is pretty inconsequential and has nothing to do with your particular query whether or not it is positioned correctly!

***

but if its pushed off its perch than oil isint maintained in the cup and contaminates can get in there and cause rust and wear over time

If you want to start a new topic, do so.

It's poor manners to hijack this thread!

***

[Chrisj CMA]

That drive shaft seal is pretty inconsequential and has nothing to do with your particular query whether or not it is positioned correctly!

***

but if its pushed off its perch than oil isint maintained in the cup and contaminates can get in there and cause rust and wear over time

If you want to start a new topic, do so.

It's poor manners to hijack this thread!

***

"Poor manners"  "hijacking"     You crack me up RickyD.  The man said he assembles the drive train in a way that could disrupt the oil seal.  If that seal is disrupted for long enough it could lead to a problem in the pinion cup. 

If its bad form to discuss any possible cause for the problem he brought up, then you will just have to over look my poor manners........we have to over look several of yours, so I guess we are even   

[Patrick]

Only Rick would think this thread has been hi-jacked.. Those who have been reading all the posts know why I installed the rear drive the way I did.. I had a reason,, upon reflection,, probably a stupid reason,, but,, a reason none the less.. Its not the first I've done something stupid and I'm sure it won't be the last.. As anal as I am,, when the HDL order ever shows up,, the bike will probably go back on the lift.. I actually want to see if any oil has drifted into the cup,, it hasn't in the past,, so this'll be interesting..