From shaft to chain with a question

After decades of pretty much shaft drives, there was a Harley (belt) and Suzuki (chain) in the mix, I am now riding a F850GS. Enjoy the bike. For a twin, the engine is quite smooth, especially with cruise control that lightens the grip. And now that I have a Sargent seat, Madstad windshield system and Suburban Machinery lowering pegs it is dialed in. However, I find the chain sag to be too much, even when set per BMW's process and permissible setting.

The process is bike on the side stand with no weight on it, measure low and high of chain mid point between sprockets - typical stuff. The problem is I can't get a correct low high point (40 to 50MM is the allowable range) because the rubber pad mounted on swing arm doesn't allow chain to move as high as it probably would. So I depress it to zero on my gauge and then push up...it will hit the rubber at 45mm, but it is obvious it could go high if the rubber chain slap guard wasn't there. Just looks and feels like chain has too much sag and a proper measurement can't be made. Any other chain driven Beemers with same problem? Never had this measurement obstruction with Japanese bikes back in the day...and allowed clearance wasn't so large.

I do it the old way- center stand, see how it looks, rotate the wheel so as I see the chain "set" in three points in its travel.....good to go. The newer generation O-Ring chains, I have found, don't need much messing with. Too tight can be more of an issue than too loose.
OM

BTW, a complete "final drive" replacement is about $200. Hardest part is the master link. There is a good thread on it in the F-Twins index.

Omega Man I need to replace the final drive on my 2015 F800R this winter. I would love to access the F-Twin Index thread about replacing a final drive. How does one go about finding this thread?

Dugh said:

Omega Man I need to replace the final drive on my 2015 F800R this winter. I would love to access the F-Twin Index thread about replacing a final drive. How does one go about finding this thread?

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It’s a “work in progress”.......One of the “stickies” here in F-Twins.

https://forums.bmwmoa.org/showthread.php?78486-The-F-Twin-Index

I was kidding about the “final drive” as there is a dislike for chain-drive bikes around here. For around $200 you can get a chain and sprockets compared to the much higher expense of a bad shaft-drive

“Chains and belts built this country”.

OM

Not sure why everyone seems to gravitate to no chain. I’ve put over 80,000 miles on chained bikes in the past 12 years and as long as you have a center stand, they are almost a non issue. A simple oiling is easily accomplished every 500 miles py popping on center stand and hand turning while spaying a name brand chain oil. I how have a shaft drive, but that was not at all a determining factor, would have just as happy with another chain. I usually spray a chain cleaner every thousand miles or so before oiling but that adds a whole extra two minutes to the process. And yes, too tight a chain is worse than a little loose, so don’t over tighten.. My F700 GS was the most maintenance free motorcycle i’ve Ever had.

Motodan, My wife Annie has put over 120K miles on F bikes and still has her F800GS. I get to do most of the maintenance so I'm pretty familiar with chain adjustment and care. As OM said loose is better than tight and in my opinion there is no need for precise measurement. I also adjust with the bike on the center stand and shoot for close enough when I move the chain up and down with a finger. And again as OM said check it at various points as the wheel is rotated. The need for adjustment is pretty rare except for when the chain is brand new (it may require an adjustment after initial use) and when it is nearing the end of its life.

I am an F850GSA owner as well and moved up from an F800GS. I seldom actually measure the chain slack, I usually can get a good sense of too loose and when to adjust it. I find that if there is just enough slack to allow the chain to just touch the guide shoe on the swing arm it's good. The GS need a lot of slack due to the suspension travel. The slack is checked with the suspension at or near full extension, the tightest point in the chain tension is when the axis of the two sprockets are in a straight line with the axis of the swing arm pivot. That point is nearer to the compressed limit of the suspension than to full extension so a lot of slack is taken up as the suspension is compressed and the reason why the chain seems so loose when checked at full extension. If the chain is too tight, it will put significant tension stress on the chain and the bearings at each of those three points when it crosses that alignment. Thus, OM is correct with his advice that you are better off a bit on the loose side.

My experience with modern chain maintenance on BMW motorcycles is limited to 173,895 miles on two F650 Funduros, one F650 Dakar, and two G310GSs. Modern pre-greased chains sealed with O rings or X rings or their equivalent last a long time before they need to be adjusted. And then, as soon as they do need adjustment they are likely to need it again very quickly. Frequency of squirting them with oil does little to prevent stretch but does prevent wear on the sprockets and rollers.

As soon as I need to adjust a chain I get a replacement if I don't already have one on hand.

I like belts

The thing about belt drive is no lube needed. I know belts are only for road bikes, belts and rocks don't mix.

weschmann said:

Not sure why everyone seems to gravitate to no chain. I’ve put over 80,000 miles on chained bikes in the past 12 years and as long as you have a center stand, they are almost a non issue. A simple oiling is easily accomplished every 500 miles py popping on center stand and hand turning while spaying a name brand chain oil. I how have a shaft drive, but that was not at all a determining factor, would have just as happy with another chain. I usually spray a chain cleaner every thousand miles or so before oiling but that adds a whole extra two minutes to the process. And yes, too tight a chain is worse than a little loose, so don’t over tighten.. My F700 GS was the most maintenance free motorcycle i’ve Ever had.

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I agree … as long as you have a clean, dry place to perform that two-minute chore. As a touring rider, I am in a different motel parking lot every night, and darned if it does not seem to be wet and muddy about half of those nights. I got mud and grease on my pants and shirt sleeves on a regular basis. I did that for about 3 or 4 years on an FZ1, before I said to myself, "Self, this is stupid. Get rid of the chain bike or ask for a refund on your two college degrees."

I have not had a chain-drive bike since. Once I quit touring I might go back to a chain, because I can clean and lube it in my warm, dry, clean garage about once a week or so.

PGlaves said:

My experience with modern chain maintenance on BMW motorcycles is limited to 173,895 miles on two F650 Funduros, one F650 Dakar, and two G310GSs. Modern pre-greased chains sealed with O rings or X rings or their equivalent last a long time before they need to be adjusted. And then, as soon as they do need adjustment they are likely to need it again very quickly. Frequency of squirting them with oil does little to prevent stretch but does prevent wear on the sprockets and rollers.

As soon as I need to adjust a chain I get a replacement if I don't already have one on hand.

Click to expand...

I would add that I have had very good results with the installation of a Scottoiler, which is also available as an OEM branded part. In the 9000 + miles I have used it, I haven’t touched the chain once. It remains lightly lubed and reasonably clean at all times. Other than having my dealer adjust it at the regular 6000 mile service, it has been maintenance free. I highly recommend it for any chain drive motorcycle.

Since 1980 I have owned one chain drive bike, a F650 Dakar that I had for only a few months. I may adopt Annie's F800GS since she doesn't ride it much anymore. Will need a new, lower shock to make it useable for me (I have a 30 inch inseam, Annie's is 34 inches)

The only bike I ever had to rent a van to haul home was due to a failed final drive. The repair cost enough to buy 10 chain and sprocket sets.