Chain too loose? Quickening loud slapping noise accellerating in first gear...

Hello everyone.

I was riding my bike today, and about halfway to where I was going (around 10-15mi away), I noticed that when I started to move in first gear, there was a loud "slapping" sound coming from the middle of the bike.

As I accelerated, the noise seemed to happen more frequently.

When I got up to normal road speeds and I passed a large truck or a van, I could hear the noise reflecting off of the other vehicle.

I noticed that there was quite a bit of play on the chain -- I'm assuming that this is what's causing the noise.

Just in case, I checked the front/rear wheels and nothing was caught in the calipers or in the spokes of the rim, and nothing was hanging down from around the instrument cluster (although that wouldn't matter, as there is a fender blocking that area), and the tires are at the proper pressure.

Thanks!

 

Don't ride the bike in that condition as a worn-out or badly-adjusted chain could cause a crash !! With injuries, painful ones !

Check that the rear axle is tight. Lift the rear wheel and spin it to find out what's happinin'.

 

Thanks for the reply.

So, I had a co-worker who has worked on bikes for his entire life look at it, and he says that I was incorrect -- the chain is not actually loose.

He told me that the chain is pretty dirty and needs a good scrub-and-lube, and that it is possible that a couple of the links are binding.

That brings me to my next point...

I might be losing my mind, but when I back my little viffer out of the parking space at my apartment complex to park in the garage, the bike likes to throw its weight around. The driving surface at the complex is very well-kept cement, so it's not an irregularity in the cement.

I'll be going straight backwards on an almost perfectly level surface and the bike keeps trying to tip itself over (most of the time, it's to the right). Now, this could just be the fuel sloshing around in the tank, but I figured I'd add this info.

When I finally get it into my garage (I have to back her in, as my garage is pretty tiny), the garage floor is perfectly level, and sometimes it randomly feels like I'm pushing the bike uphill (that is, there is spontaneous resistance to my pushing of the bike), and then it magically seems like it starts rolling normally again 6 inches later.

Unfortunately, I'm terrified that if I try to put it on its center stand, that I'll drop it, so I can't really check to see how the rear wheel spins (another one of my friends is coming over tonight, so he might be able to spot me and catch the bike in case of an "emergency). I did, however, check to see if there was any lateral play on the rear axle while it was on the side-stand, and the rear wheel feels very solid.

I'm seriously hoping that the worst-case scenario is to replace the chain and sprockets...Hopefully this additional insight gives you a little more info...


Edit:


Woops - I forgot to mention...When I'm cruising and let up VERY slightly on the throttle, the bike surges. The bike likes to lurch in a repetitive fashion at slower speeds. Forgot a very important symptom...

Thanks squirrelman.

 

Either too loose or bound up.

 

Sounds like some links are frozen or seized.

 

Check your chain and tires pressure
loose chain will touch the center stand and the chain rail that cause the noise and binding links as well. Low pressure tire will make the bike heavy and tend to tip over a side

 

Good call everyone -- apparently my diagnostic skills were lacking.

Like any good software engineer, I tried to diagnose by reproducing the problem in a controlled setting...

I put my bike in neutral, put it on the side-stand, went down to the chain, pushed up quickly on the upper portion of the chain repetitively as it would be doing when I apply a change in throttle, and BAM -- the EXACT noise that I was hearing...

So, like any good engineer, I took a measurement -- the chain slack, down to a mm, was 55.56mm.

Just so you guys don't have to break out the service manual, there is a warning box in the service manual stating "Slack above 40mm will cause frame damage", and that the proper chain tension is between 15 and 25mm.

I then re-tensioned the chain per the instructions in the service manual to precisely 20.64mm -- right in the middle of the specified range.

Unfortunately, Denver is in the middle of a very strange winter storm (2" of snow accumulation in a period of 20min, along with pretty impressive LIGHTNING; yes, snow and lightning), so I am unable to go for a test ride, but when I re-parked my bike, it did seem to roll MUCH easier (of course, the sample size is very small...I only rolled it about 5 feet).

Thanks for all of the help guys!!!

 

Most proppa way to check chain tension is pushing up on the LOWER portion under the swingarm where most of the slack accumulates.

A stock original chain usually is shot by 20-25,000 miles, so how many miles on your chain ?? After you get the rear wheel up and turn it by hand, feel for loose and tight spots, another indication of a worn-out chain, and ALWAYS adjust the chain so tension is correct ( about 1 1/4" slack) AT THE TIGHTEST SPOT !!

 

When you adjust a chain and are looking for the 1 1/4" of play are you pushing down or up on the chain? I'm getting some chain noise on my '02 and the chain is nearing the end, but I need to squeeze another week or so out of it. I'm going to clean it and lube it really well this weekend and try to take it easy.

 

Holy thread revival Batman...

OK you need to check the chain tension roughly midway between the sprockets. At that point you are aiming to assess the maximum up/down deflection to determine whether it matches the distance specified in the manual for your VFR.

Fortunately the VFR swinging arm design allows fairly quick adjustments as follows. Release the adjustment lock nut on the swingarm - use the weird tool to adjust chain slack - retighten adjustment lock nut - confirm chain slack is still within acceptable range.

Hint - As the chain tends to get slightly looser as you retighten the adjustment lock nut - I simply adjust for the shortest end of the acceptable range and normally find that after the adjustment nut is fully tight, the actual chain tension is mid-range.

Hint - My VFR comes with a two section adjustment spanner - a C shape bit with a short straight section which slots into the handle section. I marked the recommended chain slack gap directly onto that adjustment tool - by filing a couple of shallow grooves onto the straight section of the tool. So no further need for tape measures or looking up the chain slack specs.


For vtecs you are meant to check chain tension with the bike on the centre stand. If you want to be really accurate then you will need the help of a friend to hold, observe and record the chain deflection against a tape measure held beside the chain, whilst you first press the chain downwards with finger pressure only, then lift the chain upwards at the spot.

Ideally the recommended free play needs to be consistent along the whole chain length, so as you already on your hands and knees and have the bike on the centre stand you might as well check for tight spots on the chain. So with the bike in neutral gear, rotate the rear wheel trying to see if there are any obvious tight spots - watch closely how the chain meshes with the rear sprocket cogs. (Obviously if you hear the chain squeaking as you rotate it then the chain needs lubrication.)

If you see the chain lifting up on the rear cogs - its a sign that things are not right - most likely due to sprocket and/or chain wear or inadequate lubrication. Make a note of where the chain started to lift and continue to rotate the wheel until you can see the affected sprockets free of the chain - then compare the shape of the individual cogs on the sprocket with the diagram in the manual. On European models there is a sticker on the chain cover guard which shows the acceptable cog profile. If all the cogs in the area look OK, then you need to check to see if one or more of the links in the chain in the affected area is tight. Especially if the bike has not been used over winter - rust can develop preventing the link from running smoothly. If so free off the chain tensioner to allow the chain to be very loose, then apply some chain lube and then flex all the affected links by hand until they rotate freely like the rest of the chain.

If you find a tight link in one place on a chain, then there is a chance there are other tight links, so work progressively around the whole chain looking for links which do not flex freely and as necessary lube/flex until they all run freely.

If you find links where it is not possible to get them to flex freely, then its time to invest in a new chain and possibly sprockets. However if you have access to a chain riveter/splitter tool you may be able to eek a little further life out of the chain, simply by removing and then reinstating the affected link. Hopefully once the link is correctly re-installed it will flex freely - even so I would be thinking its about time for a replacement chain.

Take care - let us know how you get on.

 

Brilliant post! Thanks, this is exactly what I needed to know. I figured I was better off reviving a thread than posting a duplicate.

 

Set chain tension at the tightest spot while cold, lube while hot, a little loose is better than too tight, always lube before storage, you can't get a quality chain cheap all are virtual shibboleths of tradional chain tech.:biggrin:

wear shows up as sideways-plane bowing on a used chain, while a new chain won't.

 

Swung by my mechanics garage today and he took a minute to ride the bike and listen to it. He says it's most likely the cam chain making the noise, not the drive chain.

 

Cam chains, what are those?!?!? otstir:

 

I had the same problem recently where it sounded like the CCT (Cam Chain Tensioner), I replaced the one on the upper cylinder bank only to have the noise persist.
Turned out my chain was loose and I could have fixed the problem in 5 minutes with a chain adjustment.
unfortunately I am now seeing my chain loosen up within 300 miles of being "tightened".
I don't understand that problem.
Have lubed and adjusted only to have the chain 40mm+ slack within 300 miles.

Moral of the story, lube and adjust your chain BEFORE going out and buy a CCT (for upwards of $80 USD) and 2 hours of work on the bike.

 

If your chain is loosening in 300 miles then I'd suggest that your eccentric is turning in the swingarm. Check the pinch bolt is tight. I have also heard (but not seen first hand) that if the washer with the brake hose loop is missing, the bolt shoulder can stop the swingarm being pinched tight enough.

 

300 miles and needs re adjusted? hmm maybe just saying the chain is starting to go? how many on the chain? all though I'm kinda picky, and I actually do fiddle with it about every 4-500 hundred just because. another part to this like mentioned, find the tight spot and adjust the chain from that point, if there's more than say 30mm after, then it's time for a new chain and sprocket. there's also once done with that adjustment, sit on the bike and have some one check the chain again it can and will get tighter as the swing arm moves, so in most cases play more on the lose side of that 25mm