Vibration in low speed

[Momo1970]

Hi There,
I just changed sprockets and chain today. The bike has some vibrations in low speed 5-10 MPH that I don't remember before. The vibrations are only on low speed when I slow down before stopping. I went back to the dealer to check whether the chain tension was adjusted properly. The mechanic check the chain tension & and the alignment. He used the laser tool to measure if the rear sprocket is in line with the front sprocket and went for test ride. Of course he didn't feel the vibes. I wonder whether the vibes are related to the new sprockets & chain or whether the last wheelie that I did on the bike might damaged the wheel front bearing. The vibes feels like my front rotors are dent or something although they are in perfect condition.
Any idea?

[Silver-Bolt]

Sounds like an alignment or tension issue. Measure the amount of slack in the chain per your manual. Probably too tight.

[Kid Thunder]

Clean the front rotor buttons. When they get dirty it feels like a warped rotor.

[tmtuono]

Did you use the stock Aprilia front sprocket or did you replace it with an aftermarket?

I also have a slight low speed vibration that I think is coming from the chain. I used aftermarket sprockets. The original Aprilia sprocket has a rubber compound bonded to it that makes some contact with the chain and probably does a little vibration damping.

[Momo1970]

I just checked the chain slack, its about 15mm while it should be 25mm.
First thing in tomorrow morning I'm going to adjust the slack back to 25mm.
My front sprocket before was after market so I don't think its the new sprocket causing the new vibes.

By the way, when adjusting the chain slack, can I count on the marks on the rear swingarm for correct alignment?

[Momo1970]

I just checked the chain slack, its about 15mm while it should be 25mm.
First thing in tomorrow morning I'm going to adjust the slack back to 25mm.
My front sprocket before was after market so I don't think its the new sprocket causing the new vibes.

By the way, when adjusting the chain slack, can I count on the marks on the rear swingarm for correct alignment?

[Momo1970]

So after I adjusted the chain slack to 25-30 mm the vibs are reduced but they are still there. My question is whether the change to after marker chain and rear sprocket might make the bike to vibrate more. BTW I'm using Esjot sprocket purchase from AF1.