Drive chain tension?

My DRZ is the first dual-purpose bike that I have ever had, so I have a newbie question regarding the drive chain...  Is it normal for the chain to flail up and down when riding?  I have never noticed this on any street bike that I have had before, but street bikes have cush drives, so maybe you just don't feel it.  I have a new chain on my DRZ (a 520 sealed ring type), and I have adjusted it loosely at first, then at a little less than a half-inch of play at max length, which I thought was tight enough.  When tighter, the frequency of the undulation just rises.  I can feel it wiggle and I can see it undulating by looking at my shadow while riding...  It will stop undulating under acceleration or when completely off throttle, but when cruising at lower speeds, up and down it goes.  It has to be sapping power for roll on throttle.

 

So, did I buy a pud chain, do I need to tighten it more, or is this just the price for having long travel suspension?  My FZ1 has a longer chain than my DRZ, but it is smooth-running and I have never had a chain bounce around like that on it or any other street bike.

The manual for my 2003 KLX400SR (DRZ400) said for the drive chain to have 1.6 to 2 inches of up and down movement when you grab it at the center above the trailing arm.  

 

hope that helps.

Should have a lot more than half inch freeplay...

 

 

Look at your sprockets, it's sounds like the chain is either getting caught up on a sprocket or otherwise sticking. Were the sprockets replaced with the chain? If some of the teeth are shark toothed they could be pulling the chain too far along the rear sprockets, popping loose, pulling too far again, etc.

 

Look for uneven wear, 'shark tooth' sprocket teeth, missing teeth, etc.

Is your rear wheel balanced?  If it's not, it will "bounce" at speed causing the chain to flop up and down.  Like the guys above say, there should be a lot more chain freeplay than a half an inch!  If the chain is too tight, you'll start wearing the entire drive train out prematurely, but then you probably already know that.  The FZ1 has it's own chain tension spec, based on it's chain, suspension and swing arm geometry.

 

Where in CA are you?  Perhaps you can meet up with one us to take a look at your bike with you.

It is a single.  Fewer power pulses for any given road speed.  Yes chain flop is common.  It is called chain tension but really it is chain slack. About 1/2 inch slack is good when the suspension is compressed to where the chain slack is at the minimum. It is not really very critical as long as the chain is never tight.  You might be riding in too high a gear.  More R's should smooth things out

 

Look at your sprockets, it's sounds like the chain is either getting caught up on a sprocket or otherwise sticking. Were the sprockets replaced with the chain? If some of the teeth are shark toothed they could be pulling the chain too far along the rear sprockets, popping loose, pulling too far again, etc.

 

Look for uneven wear, 'shark tooth' sprocket teeth, missing teeth, etc.

 

I replaced the front sprocket, but not the rear when I replaced the chain.  Both looked barely worn at all, but I planned on replacing both anyway since that is what you should do.  However, I didn't have a six point box wrench and the butter-soft nuts holding the rear sprocket on threatened to round off on me with the twelve point one I had, so I figured "whatever, it's good enough."  I even held the new sprocket that I bought up next to the one on the wheel and they looked identical...  You are probably on to something, though.  This might be the problem.  The old chain was a goner and if the PO had ridden the bike with that chain much, it surely would wear the sprockets.  

 

Well, I bought a 6 point 12mm box wrench on my way home from work and put the new rear sprocket on.  I will ride it to work tomorrow and see if that makes a difference.  

Is your rear wheel balanced?  If it's not, it will "bounce" at speed causing the chain to flop up and down.  Like the guys above say, there should be a lot more chain freeplay than a half an inch!  If the chain is too tight, you'll start wearing the entire drive train out prematurely, but then you probably already know that.  The FZ1 has it's own chain tension spec, based on it's chain, suspension and swing arm geometry.

 

Where in CA are you?  Perhaps you can meet up with one us to take a look at your bike with you.

 

Yes, the wheel balance is perfect.  It is the chain.

 

Actually, the spec. freeplay has been the same on every bike that I have had:  about 1.6 inches.  I thought it would be more than that with a long travel suspension...  I just used a method I heard on the internets and compressed the suspension so that the sprockets were lined up with the swingarm and there was about 1/2 inch of play.

 

I am guessing by the Stone Brewery avatar that you are in the San Diego area?  I am in Vista in North San Diego County myself.

It is a single.  Fewer power pulses for any given road speed.  Yes chain flop is common.  It is called chain tension but really it is chain slack. About 1/2 inch slack is good when the suspension is compressed to where the chain slack is at the minimum. It is not really very critical as long as the chain is never tight.  You might be riding in too high a gear.  More R's should smooth things out

 

Low RPM does seem to accentuate it...  I replaced my rear sprocket and loosened the chain a little.  I guess that if that doesn't quell the undulating then it is just how the bike is.  I checked to see if the new chain had tight spots, but it seems fine...  The rollers and the guide look fine too.

Alrighty then, problem identified.  Replacing the rear sprocket drastically improved it.  The chain still undulates a little, but nothing like it was doing before and not enough to consume engine power like it was doing before.  It just goes to show why you should replace the sprockets at the same time as the chain.  It's pretty amazing that the imperceptible amount of wear on that rear sprocket was causing that commotion!

Alrighty then, problem identified.  Replacing the rear sprocket drastically improved it.  The chain still undulates a little, but nothing like it was doing before and not enough to consume engine power like it was doing before.  It just goes to show why you should replace the sprockets at the same time as the chain.  It's pretty amazing that the imperceptible amount of wear on that rear sprocket was causing that commotion!

 

Maybe I should change my chain and sprockets...

 

I don't know if my PO ever did. How many miles til a chain and sprocket change?

Maybe I should change my chain and sprockets...

 

I don't know if my PO ever did. How many miles til a chain and sprocket change?

The easiest way to check your chain for wear is, on the rear sprocket, at the back, think of an imaginary horizontal line. pinch one of the chain links and pull backwards.

If you can uncover more than half a tooth on the sprocket the chain is worn out and if the chain is toast, so are the sprockets. 

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