Hello,

I am currently travelling with a friend around Mexico and central America. I have been on the road for about 3 months now on a 99 BMW F650 and have done about 10,000 miles. I recently serviced the bike, about 3,000 miles back. I am now in the resort of Playa del Carmen, in the Yucatan region.

The problem I am having is: as I pull away from first or open the throttle from low revs in other gears, a loud rattling sound emerges from the bike. At higher revs and at cruising speed there is no noticeable noise. I thought perhaps the chain was rattling but I have checked this and it seems fine. I am now unsure whether to continue riding as I dont wish to break down in the middle of nowhere! Does anyone have any idea what might be causing this?

Thanks for any suggestions.

That's really tough to diagnose - if it were me I would do a very thorough check of every nut and bolt I could get at, and also checking for loose sheet metal parts, and signs of rubbing etc everywhere.

If you can find a local mechanic let them have a listen as well, their more experienced ear may be able to spot it immediately.

If it's clearly nothing external, get it to a mechanic asap!

------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

Thanks for the speedy reply to my post. I have managed to locate a repair shop in this town so I will take the bike there and see what they think. I have a feeling I wont be able to fix this myself!

I have also tried phoning a BMW dealer in the US and they advise that the cause may be a transmission problem. If so, its end of trip!

Relief! I have been riding the bike in circles trying to identify where the noise comes from. It seemed to be from somewhere near the rear wheel. I then tried sticking it on the centre stand, engaging first, and revving the bike. It then became obvious the chain was skipping off the rear sprocket. The chain was tight in some areas and slack in others. The first time I checked, I only checked one part of the chain, not the whole thing. So the chain is shot - this is good news as I should be able to find a new set round here.

Thanks for your help.

Well done!

Now have a close look at the new sprockets when you get them. You will notice that the teeth are uniform in shape on both sides (looking at it from the side).

As the chain wears, it stretches - gets longer - as the bearings in each link wear. This puts huge stress on the last tooth or two as the chain rolls off the sprocket at the top, causing very high wear.

This causes "hooking" (where the tooth shape is no longer uniform) - and any sign of hooking means the sprocket is worn out.

The real trick is to replace the chain before it destroys the sprockets as well. One set of sprockets will outlast a hundred chains - if you replace them every 1000 miles!

So what we want to do is get the max life out of the chain and sprockets, replacing the chain JUST before it damages the sprockets.

My experience has been that a good general rule is when the chain is correctly adjusted, at the very back of the rear sprocket, try to lift the chain off the sprocket straight back. If you can lift it about 1/2 the height of a tooth, then the chain is done. Slightly sooner is good.

Also as you learned, chains wear unevenly, and get loaded up with sand and grit, which gives you the huge unevenness in chain tension. Always make sure that the tension is set at the TIGHTEST point on the chain. Otherwise you could destroy the transmission sprocket, chain, rear wheel bearing etc.

If the unevenness gets excessive, thoroughly clean the chain, if that doesn't help, it's time to replace it - but first check that the sprockets aren't out of round.

You may not be able to get new sprockets - note the plural there - but you should be able to get a chain that will work. It will not be as good as the original, but it will get you rolling.

Good luck!


------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

Thanks again for your help, those tips will come in very useful.

As a side note, I have been reading up on chains/sprockets on the Chaingang website www.f650.com Some suggest not to use WD40 on an O-Ring chain as this contains solvent that will penetrate the bearings and cause rapid wear. I have been using WD-40 moderately and not using any form of lube. This is following advice from a BMW mechanic. I suspect this was bad advice?

I've read somewhere that some people recommend WD40 or similar for desert conditions, as the sand is less likely to stick to the chain & wear it out?

Everything Grant said re: chain tension is excellent advice. In addition to the damage he listed, too tight a chain can also cause the bearing behind the front sprocket to collapse, taking the gearbox with it & causing the rear wheel to lock. Happened on a friends recently purchased GSX-R750, fortunately at low speed & without injury.

Steve

__________________
My photos: www.possu.smugmug.com

Hello again,

I´ve been inspecting the sprockets and unfortunately they are also in need of replacement. I´m going to have to find a BMW dealer in Mexico, or failing that, get new sprockets from the US! Oh well, could be in Playa del Carmen for Christmas.

Hello.
I mentioned in an earlier post using wd-40 on 0-ring chains for cleaning and driving out water after you wash your bike. I supose if you soak the chain with a large amount and let it settle, it might penatrate the o-fing and dissolve the grease. I've always sprayed it on a rag and wiped the chain clean that way. The residue left over is only a thin film. which i believe will not cause any damage. This has worked for me for over 20 years, leaving me with clean, long lasting chains. Just remember to use a chain-wax lube that doesn't pick up dust and dirt.
Good Luck!

Just read the post.... Have a similar kind of regular grating noise that increases with speed. I know its related to the chain and have been told by mechanics in the US that this sometimes happens on chain drive bikes. Sprockets look ok, nothing odd there.

Hmmmm....I´ve got an africa twin & just had the rear tyre replaced in Mexico. If you are near Leon, I can reccomend a good outfit.

Cheers and Feliz Navidad!

__________________
http://www.trailsunexpected.com

This sounds familiar. My F650 tales of woe include many chain and sprocket problems. I even once used something like WD40 on an O-ring chain only to find that it caused it to have a major slack spot which also hooked the rear sprocket (the speed with which this happened was alarming).

It seems that getting the right combination of chain, lubricant and cleaner for the weather and road conditions is critical (and beyond my patience).

The worst performing chain that I had was a stock BMW chain that lasted only 3000 miles in dry UK summer conditions, having been adjusted, cleaned and lubed every week.

A scottoiler proved effective in the UK winter, acting as a lubricant, cleaner and making rear-wheel traction somewhat more exciting, but in the summer only caused more gunge to collect.

At one point I had an expensive gold coloured Renthal x-ring chain and sprocket set that lasted 10,000 miles, mostly in the summer. This was very slightly scottoiler lubricated, although i've heard it said that in very dry, dusty or sandy conditions, it's best not to lubricate at all.

Well that's the end of my rant concerning chains! Now I have a R100GS i only have to worry about the shaft disintegrating every 40,000 or so.

Hokay, so my chain is knackered.

Noticed that the master link hardly exists anymore and that the two pins and a tiny bit of metal in the middle of the link is all that remains.

Hows does this happen? General wear and tear? Both chain and sprockets were new at the start of my trip in Montreal, I'm now in Mexico, and must have done a fair few k's.

Thankfully got my girly coming over from the UK shortly, with new chain and sprocket set. Lucky me!!

__________________
http://www.trailsunexpected.com

colesyboy, a modern chain should last on the order of 20-25,000 miles. WITH proper maintenance. Or better in ideal conditions and religious care.

Calculate from there...

------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

Hey guys, this might help. Bikes with long travel suspension(eg. KLR, KTM) can be very tricky! The chain seems loose until you load the suspension and is finally tight at the end of it's stroke. It could be your chain is too tight and stretching pre-maturely. Also, stand 6-8 feet back from the bike and sight down along the chain and sprocket to make sure they are paralell and in line. You can also check the last tooth engaged in a link, looking down from the top, and see if it's centered in the chain. Perfect alignment is crucial to chain and sprocket life. It sounds like the chain has stretched, causing the clicking noise, or it may be out of alignment.
Good luck!