Vibration

[xs400neophite]

Hello all,
Happy Fathers Day to all you Muthas out there.Hope all is well.

I have been wringing the hell out of the little beezie all over the place and loving it!

Something that has developed and actually has been there all along, is major, major vibration. Like hands going numb on the throttle vibration. The rubber grommet on the gas tank,in the back, keeps getting cut from all the vibration going on
I was wondering, what can cause excessive vibration?
Timing?
Carb Synching?
Let me know what y'all think

 

[xschris]

Make sure all your engine mounts are good and tight.

 

[ThePsuedoMonkey]

Nothing else can cause that much vibration without getting you tossed from the seat.

 

[Drewcifer]

check that you have the proper sprocket installed and your chain tension is correct. Then check that your triple is correctly adjusted. Sounds like you have a loose or out of spec drive train element.

 

[xs400neophite]

Just an update on my little situation.
I checked the mounts and all good.
I dont even know how to adjust the triple
The chain however, was out of spec ...dead on Drewcifer with the drive train element out of spec ...impressive Sir!
Sprockets are stock from factory and never touched.
I am humbled to know that a little stretch on the chain can cause that much vibration.Checked the chain 400 miles ago..... I know I know the manual calls for every 200. Again, humbled to know how important reg. maintenance is for a properly working bike.
I will test run the bike tomorrow and see if that smooths things out. Thanks again guys.


P.S. Maybe running the little beezie a bit to hard, stretching the heck out of the chain?

 

[bcware]

I am humbled to know that a little stretch on the chain can cause that much vibration.

It won't.

A loose chain might slap the swing-arm on take-off and at very low speeds, but it will not cause any sort of vibration.

A loose steering stem will cause wobble and head-shake, but not vibration.

If tightening the chain fixes your problem I will be impressed!

If the motor mounts are good check the wheel balance.

 

[bcware]

Oh, and while you're at it make sure you check the chain properly; a chain must be inspected every few inches. Loose and tight sections can develop over time; i.e. the chain can be loose in one spot and too tight in another. Adjust the chain play in the tightest section.

If you have loose and tight sections the chain needs to be replaced. A good chain should have the same deflection throughout. Chains and sprockets need to be replaced at the same time to prevent premature wear on the new chain.

 

[xs400neophite]

Thanks bc, been a while and glad to hear from you.
Yeah I dont know if it will be the chain or not. I have had this vibration from the start. I just assumed it was how the XS ran. Feels like something is unbalanced. She runs fine in low rpms. In the mid rpms, she seems to be the worse. Higher rpms she seems ok. I will search my videos for a good sound bite.

 

[Drewcifer]

Hi buddy,

The chain and the sprocket are capable of LATERAL movement if they are out of spec. Vibration is caused by movement that is not intended on a given axis. (a wheel shimmying instead of just spinning.) in rare cases a mashed rim could vibrate up and down too, but that's more rare than the side to side version...

So unless you have bent piston rods in which case it's easier to find a new engine....

The only parts of the bike that can move laterally (most vibration) opposed to their ideal trajectory would be....

Rims

Sprockets

Chain

You can eliminate a few by filling the tires to spec, getting a chain and sprocket on there that are new (my chain is so stretched that there's no more room to dial out the adjustment!)

and you can also feel the engine when it starts up from cold and see if the vibration is at speed or only at idle and coming from a specific place on the engine before it heats up.

Hopefully between my intuition and BC's knowledge we can track down your vibration. I'm guessing at things at a distance with very few clues, but then again, I am a lot like Dr House. Sometimes my first guess is right.

So, then. A challenge. I contend that the chain and sprocket are the cause of the lateral movement and the rims or pistons would be the next place to look for abnormal travel on a trajectory...

BC aware? What sir is your hypothesis!?

This will be fun! the game is afoot.

Drewcifer, MD (motorcycle doctor.)

 

[Lou Ranger]

So, then. A challenge. I contend that the chain and sprocket are the cause of the lateral movement and the rims or pistons would be the next place to look for abnormal travel on a trajectory... BC aware? What sir is your hypothesis!?

This will be fun! the game is afoot.

Can others make side bets? I know nothing about the mechanicals of motorcycles so I would draw only on my experiences with cars over 40 years and say that the PO didn't balance the wheels, or when a balance weight fell off he didn't replace it 'cause he was selling.

 

[Drewcifer]

Wheel weights would fall under the category of rim imbalance, but yes, you may wager sir! Wheelweights for 250 For the gentleman Lou Ranger! (because this could be fun and solve it for him too!)

 

[ThePsuedoMonkey]

I daresay I would wager a dime upon a spent bushing :monocle:

Is the vibration only when riding, or do you always notice it?

 

[drewpy]

I'd tune the bike up, from valves to ignition.

make sure the head steady is installed correctly so it dampens vibrations out. (under tank)

 

[Drewcifer]

Pseudo, Love the monocle old chap.

 

[Lou Ranger]

Is the vibration only when riding, or do you always notice it?

Brilliant question. I would like to split my bet Drewcifer.
Wheelweights for 125 - and the other 125 that, upon close inspection and subject to independent analysis and verification, xs400neophite will be found to have a permanent vibration in his knickers.

 

[xs400neophite]

Lou Ranger has it!! The bikes is in perfect mechanical order.. my knickers however seem to be the source of the mysterious vibration.
Hahaha just kiddin.
The California kid got it. Test rode the bike with the chain in spec(3/4") and under load... and also downshifting, the bike is smoother and the hard chop is gone. Well Ill be a psuedomonkeys uncle! Who would of thunk it? I think the loose chain was chunking on the front sprocket? (Lateral movement?)

I read the post, Drewp, sometime ago,about the factory installers installing the bushing in the head steady ..backwards? I recall checking and mine were ok.
A tune up- valves to ignition- would not hurt though.
Bc...time to be impressed buddy.
Thanks to everyone for playing and we will see you all here next time on
"GUESS MY VIBRATION!!"
(que outro music)

 

[bcware]

I lost the bet At least I learned something!

 

[ThePsuedoMonkey]

Pseudo, Love the monocle old chap.

I was really hoping that one would show up!

... Well Ill be a psuedomonkeys uncle!...

 

[xs400neophite]

I still have to change the chain and sprockets.. so you get credit for that Bc. I get no credit because I suck and let it get this way. I am thrashing this cherry bike

 

[Drewcifer]

I have to say, I was blindsided by the suggestion that wheelweights could cause that vibration, and it was a brilliant suggestion.

BC, you are a brave warrior and worthy foe!

I was lucky in my first guess, and want to remind everyone that a chain that is out of spec can break and cause a fatal accident. Tires and Chains are causes of accidents, so please replace them when they get badly out of spec. I am due for a chain and rear tire this month.

Ride safe!

Drewcifer