Rhythmic clunking, vibrations hard to explain.

Bought my first bike this summer, 78 KZ650 C2. It's been fantastic, runs great. Put new tires on it and changed the oil and I've been riding it all summer. I'm not very mechanically inclined but I'm not afraid to learn.

Yesterday I noticed a feint, rhythmic vibration on the foot pegs when I hit the breaks. Today it seemed to get a little worse and I noticed it while just coasting and not braking. Braking is smooth and I don't think it's the problem. It feels like I'm riding over evenly spaced tiny bumps in the road. Like something is catching. Sorry for the poor description.

Anyone have any ideas or offer any advice as to what I should start checking to figure this out? I've cleaned and oiled the chain a few times throughout the summer but I don't really know if the chain could cause this and frankly I don't know how to spot a worn chain.

Any help or suggestions are appreciated.

Something rhythmic that increases/decreases speed regardless of gear and engine speed is attributed only to the chain and front/rear wheels.

Rarely, but sometimes, there can be a problem with the transmission/output shaft assembly.

There is a number of easy things to check:
Start with brake discs since you felt it there first - Disc warp/wear/damage Pads - wear, damage, stuck debris.
If drum in the rear - dissasemble and spec for wear/damage.

Wheels - Tire pressure, wear/damage/ balance/trueness.
Bearings - Spec, wear/damage, maintenence.

A chain is basically considered worn when it exceeds its origional length by 2% Your service limit is 323mm over a 20 link pin2pin length. Measure in several spots.
Check alignment too. It should ride on the center of the sprocket, not hard to one side or another, a little off is ok.

The manual is the best source for maintenence and ideas as to where the problem is.

GL.

Would suspect kinks in drive chain.

And also inspect rear sprocket for wear.
Sprocket teeth should not be missing, hooked (dished), sharp, broken, or worn away.

Good Fortune!

[Click on image to enlarge view.]

To verify, put the bike on the centerstand(if you have one) and by hand spin the wheel with the bike in neutral.

You'll quickly see if there are tight and loose places in the chain. When replacing elements of the drive mechanism, always buy new front and rear sprockets along with a quality chain.

When considering changing sprocket sizes, I use www.gearingcommander.com

Thanks for all the advice,

I'll check it out this weekend and hopefully it turns out to be something suggested here.

If there is a kink in the chain, does that generally mean it need replacing?

MFolks wrote:

When replacing elements of the drive mechanism, always buy new front and rear sprockets along with a quality chain.

+1 Yes, absolutely.

New chain old sprockets, and vice versa, will wear down super fast. All three should be new/excellent condition.

My experience is that once an o-ring style chain starts kinking, it's worn out or close to being worn out. And that lubing may help a little, but only for very few miles.

More importantly, it's dangerous to life and limb when a drive chain breaks while riding.
And may also damage the engine cases and other bike parts.

Good Fortune!

id say start at one end and work your way to the other,clean/check/tighten/lube everything in between

Are you a front brake mostly style rider? If so check the front tire for "cupping". Are you running air pressure in your tires as your owners manual recommends or the pressure the tire manufacturer recommends?

The tires are new so no problem with cupping, also, I run tire pressure based on advice from these forums, I have a 120/90-18 rear (36psi) and 100/90-19 front(32psi).

Didn't have a chance to check the bike this past weekend, too busy, but I'll be checking it today. I was able to grab the OEM part numbers for the drive chain and rear sprocket from the Kawasaki website for my model, but I'll be damned if I was able to find a part number for the front sprocket? Any body know where I could find this? Also, other then front/rear sprocket and chain, anything else I should be ordering that I'm not thinking of?

Thank goodness for this forum, you guys are great.

You may not find that chain from the manual, it's 30 years old.

Go to Z1 Enterprises and buy the chain and sprockets they have for your model. If you can afford an x-ring chain (about $90) go for it. I did 30,000 miles ago and am about to replace it this week. I think that's great life for a chain and the price is good.

bloglos wrote:

The tires are new so no problem with cupping, also, I run tire pressure based on advice from these forums, I have a 120/90-18 rear (36psi) and 100/90-19 front(32psi).

Didn't have a chance to check the bike this past weekend, too busy, but I'll be checking it today. I was able to grab the OEM part numbers for the drive chain and rear sprocket from the Kawasaki website for my model, but I'll be damned if I was able to find a part number for the front sprocket? Any body know where I could find this? Also, other then front/rear sprocket and chain, anything else I should be ordering that I'm not thinking of?

Thank goodness for this forum, you guys are great.

You'll need part #92024-44 20mm lock washer for the engine sprocket (don;t reuse the old one and be sure to use the locking agent specified in the FSM)

The 16 tooth engine sprocket is part #13144-063.

Ed