[JRCollings]

Ok well I suspect this is probably rather a 'dumb question, but to me, the dumbest are the ones you don't ask... and there is a LOT of experience on this forum, so I would appreciate your thoughts and comments - DO try and be helpful as well as calling me a dumbass!

On Saturday I had my Sprint up on the center stand for cleaning, oil checking, etc.... So I ran the engine to warm and circulate the oil before checking.... and I have been experiencing 'some clattering noise' so I decided to pop the bike into gear and have a listen.... well I knocked it up to about 3 /4th and left it on tickover while I walked around and looked (yeah yeah it will leap off of the stand and run away, ok got that one out of the way...).... and I noticed the bike was 'shaking up and down' pretty badly - the frequency of this changes with the speed of the back wheel - so obviously something to do with wheel balance / not being round / etc I suspect... Now I have done this in the past with other bikes and they do NOT exhibit this, the wheel just spins... So... I looked at the end of the axle and that appears to be centered.... I looked at the wheel rim and that appears to be round (looking at the top edge to see if it 'goes up and down' as the wheel spins)... I looked at it from the back to see if it 'moved from side to side' - looked ok... very slight side to side.... However, I DID notice that the brake disk and ABS ring WERE moving up and down slightly as the wheel rotated (I would guess 1/8 - 1/4 of an inch).... And also 'the top of the tire' when viewed from the side seemed to be slightly. So my dumbass question is: Does this sound normal / acceptable to you or what do you think the problem could be and how should I go about rectifying it.... I AM thinking this could explain some of the 'lack of confidence' the bike seems to exhibit, especially at certain speeds and when cornering.... I don't want to take it back to the dealers and look a right dick getting into it with them if there is nothing wrong, but all my experience and mechanical knowledge is telling me this is not right or a good thing - so flame away please!! Oh and Oldndumb & Dave - I especially want your input!

 

[oldndumb]

Not a dumbass qustion at all.

If the rotor is correctly bolted, it will travel concentric with the rim. Trying to determine if the rotor and tire have differing amounts of run out is difficult to do visually, unless they are gross deviations. Couple the difficulty of precise visuals, along with the chain slack causing snatching when running on a stand, and you have an imprecise condition.

If it were me, even though I doubt that the rotor fasteners are the problem, I would first check that none were loose. Then I would verify that the wheel tire assy was in balance. If the balance checked out good, I would then be looking at the wheel bearings.

I see advice dispensed here and in other forums about how to check the wheel bearing and re-lube it. Most of that advice is incomplete and possibly detrimental to the life of the needle bearing. It must be removed (PIA) from the eccentric, cleaned, and repacked with the specified amount of synthetic grease. I also suspect some shops of doing it the easy, but wrong way.

I am guessing the problem will just be an out of balance tire.

 

[JRCollings]

Excellent advice / information - Thank you very much! No prizes for guess what I shall be doing later in the week!

 

[pmackie]

and I noticed the bike was 'shaking up and down' pretty badly - the frequency of this changes with the speed of the back wheel

I think it is quite an interesting question. The oscillation you observe may be a problem, or may just be an illusion or harmonic vibration, but better to be safe then sorry. I would check:

1. any play in swingarm or wheel bearings?
2. any loose parts, rotor, axle, sprocket, caliper?
3. tire & wheel showing any damage or dings? Any uneven or cupping wear on the tire?
4. how are the chain and sprockets? (I would look carefully for any tight and loose spots on the chain and inspect the sprockets for wear. This would be my suspicion area)

If nothing obvious, then a wheel balance would be next, but start with the easy (and inexpensive) things first.

 

[jeffrichards1966]

In the same situation and the bike still in warranty I'd get it booked in pronto and use the dealer's experience/warranty. How many stories do we read of new bike's with problems that shouldn't escape the factory/dealer inspection but do? Lack of confidence in corners is a fundamental concern.

First guess would a be back to basics one - wheel balance, as per OND. Usually only pronounced at certain speeds, eg 60-80MPH in my experience.

Re the clacking noise - it's a new bike so still "bedding in". I noticed my own clack reduced when I switched oil, tightened the chain (not a tricky job) and the local garage spotted that my clutch had too much free play in it, so tightened it up.

I've put Roadsmarts (Dunlop) on and feel the difference versus the stock Bridgstones in cornering confidence; probably more subjective an area and plenty of posts on that topic in the forum.