likely culprit of (engine?) vibration?

[Phil B]

I just had my front and rear tyres replaced (stock, to pirelli sport demon), and also my chain lubed, and serviced.

I have now noticed, at about 40-50mph, a rythmic vibration kinda similar to when I idle.
(very even, between 1-2 beats per second varying on speed of bike)

it's overlayed on top of the regular 5k rpm type vibrations :-} which seem quite regular, so I dont think its any kind of misfire or something.

I feel this mostly through the footpeg.

Hmm. I also installed R&G sliders recently, which replaced the engine bar. Could overly tightening that, cause excess vibration?

I'm going to take it back to the dealers and ask them to test ride it. However, in case of cluelessness, can you folks suggest the most  likely culprit for this new vibration?

Or, things I could try myself, to try to isolate what the cause is?

It's a somewhat strong vibration, so its a bit worrying. On the other hand, I dont want to blow $250 for mechanic's time to give the bike a full look-see, if its just something silly :-/

[burning1]

You say that the vibration matches the speed of the bike? First thing I'd do is try to narrow down what part of the bike the vibration is associated with. First, in a safe situation, away from traffic, produce the vibration... Then check:

1. When you pull the clutch in, does the vibration go away?
2. When you shift gears, does the vibration change in speed or intensity?

If neither 1 nor 2 is the case, it's very possible that there is a problem with your chain or tires. I'd suggest checking your chain slack... Too much, and the chain slaps creating vibrations. Also check for tight-spots in the chain. If not that, it's possible that one of your tires is improperly balanced or out of round. The shop can check for that.

[Phil B]

You say that the vibration matches the speed of the bike? First thing I'd do is try to narrow down what part of the bike the vibration is associated with. First, in a safe situation, away from traffic, produce the vibration... Then check:

1. When you pull the clutch in, does the vibration go away?
2. When you shift gears, does the vibration change in speed or intensity?

If neither 1 nor 2 is the case, it's very possible that there is a problem with your chain or tires. I'd suggest checking your chain slack... Too much, and the chain slaps creating vibrations. Also check for tight-spots in the chain. If not that, it's possible that one of your tires is improperly balanced or out of round. The shop can check for that.

I just thought about the clutch today after posting. But I did already notice #2. It didnt really seem to. maybe a little bit. but I'm not sure that it wasnt just the effect of the engine RPM change underneath it.
It's interesting that it's only mostly noticable between 35-55

I would hope that a NEW tire is not out of round But thanks for giving me ammo that they potentially did not do the install or chain adjust right.

[GI_JO_NATHAN]

I would say it's most likely gonna be related to the tire work you had done. Along with pulling in the clutch like burning1 said, try changing gear when you feel it to see if it stays about the same for the same speed. I would for sure take it back to the steeler and let them know it didn't feel like that before.

[adidasguy]

Chain lubed?
Put on center stand. Rotate rear wheel. Is there any periodic grinding or noise?
When riding, does the vibration seem to be coming from the left foot peg?

I had a chain that was not maintained by the PO. When I lubed it, the O rings swelled up - causing a VERY stiff chain. Some links would hardly move with pliers.

I suggest you check the chain. Been there - had it happen. Replaced the chain. All OK now.

PS:
OK - I see you said footpeg. That would be a stiff chain trying to go over the small front sprocket. Put a white or other mark on a link of the chain. When you rotate the rear wheel, I bet it happens with each revolution of the chain.

[Phil B]

Chain lubed?
Put on center stand. Rotate rear wheel. Is there any periodic grinding or noise?
When riding, does the vibration seem to be coming from the left foot peg?

actually, the RIGHT footpeg.

Although it doesnt seem to have much lube on it.

PS:
OK - I see you said footpeg. That would be a stiff chain trying to go over the small front sprocket. Put a white or other mark on a link of the chain. When you rotate the rear wheel, I bet it happens with each revolution of the chain.

erm.. what "it" is happening in this scenario?

[adidasguy]

As you rotate the rear wheel, you'll feel or hear a grinding or other sound from the chain each time the chain goes around. May be more than once each rotation, but it will coincide with each revolution of the chain, not each revolution of the rear wheel. That's how I determined it was the chain. I felt it more from the left peg.

Also, I noticed the chain tension varied as the wheel was rotated. Then I noticed some links did not straighten out - they stayed in a zig zag position.

I suggest checking the chain carefully before going back to the dealer. That's free to do and easy.

I suppose for the right peg, it could be transmitted through the clutch to the right side. If it was wheels, I think you'd feel it equally on both pegs.

R&G sliders shouldn't be a cause. Engine is supposed to be in there tight.

[burning1]

BTW... Have you checked your oil level?

[Phil B]

After they just CHANGED the oil?
I would be soo pissed if it were low...

[GI_JO_NATHAN]

I had a chain that would do what Adidas is talking about. But I only really felt it a low speeds, at highway speed it felt normal. I went ahead and replaced the chain and both sprockets.

[the mole]

As burning said, if you just had the tyre changed and the vibration relates to road speed rather than engine speed its most likely a tyre balance or chain adjustment issue. First thing I'd do is check the chain tension, preferably with a friend sitting on the bike holding it upright rather than on the stand, and roll it along a little and re-check (do this a few times) to check for tight spots. If you have tight spots, adjust to the correct tension at the tightest point. if that doesn't cure it, I'd go back to the shop and get them to balance the wheel properly.

[Phil B]

BTW... Have you checked your oil level?

what brought this to mind, by the way?

Its tough to tell with new oil, but it seems a bit on the low side.

[burning1]

If it's visible on the dipstick you don't have a major problem. I forgot that you had just had it changed... But before my engine died an oil level related death, there was a new vibration I noticed.

[dread_au]

If its only happening while moving I would also check the front sprocket if it was not changed with the chain.

[Phil B]

Mystery partially solved.

First, a bit more information, to throw you off the trail possibly

It seems like pulling the clutch in, actually makes the vibe get less.

Now the potential "solve"....



Yes, it IS a bit low on oil....


and GETTING LOWER!

As GI_JO would say, "the stealer" CANT EVEN CHANGE THE OIL RIGHT??

I noticed it was dripping, when I was filling up this morning. ARRG!

(I also previously noticed, "Hmm, whats that smell, is it burning oil?", but kept forgetting about it 
Now I know. oil dripping on the little cable 'round the front. grrrr)

[Phil B]

More info!
They said that the filter o-ring "wasnt sealing properly". So they put in a new o-ring and filter.. still leakage.. so they added some "sealant" as well, and that seems to have done the trick.
So far :-/

Now my bike seems back to mostly normal vibey on the footpegs.
Which is a little annoying; I think the left side may have been quieter during the problems

To revisit people's suggestions on checking a stuck chain link, though:

I got it on the centerstand and rotated the rear wheel by hand. No obvious stickie bits. One thing that I did notice, though:
When i rotated it one hand-length at a time, the chain seemed to bounce up and down a fair bit .
Is that good? or does that say "not enough tension", or something?

(Although oddly...when I push against the chain up and down with a stick, on the side stand.. it seems to have almost NO free play.. ? ! ? )

[burning1]

No free-play is odd. Is it possible that your chain has a tight spot? Usually you want the chain to have about an inch and a half of freeplay at it's tightest point. If you go from an inch and a half to no freeplay on a single rev, it's likely you have a kink or a tight point, which can cause vibration.

[Phil B]

It all looked "smooth" to me. I wonder if the previous owner "upgraded" one of the sprockets, and should have added a link, but didnt.

Then again, I think it's just the stupid dealer misadjusting the chain. I dont think I had this issue before I took it there.
Is it safe to ride "hard" like this? I was planning to go out canyon riding tomorrow as it is.

 

[burning1]

It's hard to say without seeing it, but no freeplay in the chain is dangerous.

As the rear suspension compresses, the chain tightens. If there's no freeplay, the suspension will end up yanking at the countershaft of the transmission, likely causing damage to the bearings. It also interferes with the action of the rear suspension.

With the bike on the side stand, there should be 1.5 inches of play. Sit on the bike... Is the chain stretched out? No freeplay? If so, you should have it checked out.

[Phil B]

Urrrg.
If I push HARD, it has about half an inch.   Hrrm.
Dangit, I'm gonna miss all the good saturday rides if I wait to get this checked out. sigh...