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F800GS cam chain and cam chain tensioner


14TLC

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Hi Everyone,

 

Has anyone been playing with aftermarket cam chain tensioners on a F800GS? It is quite annoying to see low mileage engines with cam chain rattle on startup or when the engine is at operating temperature. I also own F800GS and I can hear this issue is starting to develop and my bike is with 35.000 Km.

 

I don't believe that the cam chain itself is the issue on such low mileage. I suspect that maybe the tensioner is the issue. I found this mechanical tensioner on internet that might help

 

http://www.southerncaliforniamotowerks.com/store/p45/F800GS.html

 

 

 

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dirtrider
45 minutes ago, 14TLC said:

Hi Everyone,

 

Has anyone been playing with aftermarket cam chain tensioners on a F800GS? It is quite annoying to see low mileage engines with cam chain rattle on startup or when the engine is at operating temperature. I also own F800GS and I can hear this issue is starting to develop and my bike is with 35.000 Km.

 

I don't believe that the cam chain itself is the issue on such low mileage. I suspect that maybe the tensioner is the issue. I found this mechanical tensioner on internet that might help

 

http://www.southerncaliforniamotowerks.com/store/p45/F800GS.html

 

 

 

Afternoon 14TLC

 

My 800GS also had a cold  cam chain rattle, even brand new, I shimmed the tensioner spring a little & that seemed to help. 

 

There has been reports that BMW slipped a slightly stronger tensioner spring into production on the later bikes so possibly a new tensioner spring might help.  (I can't confirm this as I just shimmed my original spring).

 

On the mechanical tensioner, those things make me nervous as a slightly loose cam chain cold causes no issues but an overtight chain hot is detrimental to chain life (the 800 cam chain is already a slightly weak area)  so putting extra stress on it is not something I want to take a chance on.  Changing that 800 cam chain (correctly) is an engine removal & disassembly so THAT is definitely something to avoid if at all possible.

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Hi dirtrider,

 

Did the shimming also helped to reduce the cam chain noise when the engine is hot?

 

Have you tried different engine oils to see if it helps a little bit with the cold starting rattle?

 

There is indeed a new cam chain tensioner from BMW. The spring is different and also the bolt cap is slightly longer. The piston is the same. Friend of mine changed it and it made just little difference in the first 1000 - 2000 Km. After that it was the same.

 

I agree on the cam chain replacement procedure. It is a massive job. Fortunately there is an alternative method which I have been using on other bikes. This guy made a video of that method on a F800

 

https://www.youtube.com/watch?v=sZbnuXugS-s&t=821s

 

It seem that is not so uncommon for the F800 cam chain to get stretched and loose at low mileage

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dirtrider

Morning 14TLC

 

Did the shimming also help to reduce the cam chain noise when the engine is hot?-- On my personal 800GS I never had much "hot engine" cam chain rattle, mostly cold. Plus if the engine stopped with the cams pulling the chain on the opposite side of the tensioner there was usually no start-up rattle. 

 

Have you tried different engine oils to see if it helps a little bit with the cold starting rattle? -- Sort of, I have a 2015 800GS so the oil choices in the U.S. that meet the Ma 2 & other 800  oil requirements are very limited. My 800 transmission  shifting (actually clutch release on shift) is kind of critical so I pick an oil that gives me the best shifting for the longest time frame. But to answer your question, I haven't found oil choice to have much effect on the chain rattle. Now FRESH oil does seem to have an effect (before my spring shimming anyhow). This is something to keep in mind when someone posts this or that oil helps an engine noise. In most cases it isn't the brand or type of oil that made the difference but simply installing FRESH un-sheared (thicker because it's new) oil made the difference. 

 

There is indeed a new cam chain tensioner from BMW. The spring is different and also the bolt cap is slightly longer. The piston is the same. Friend of mine changed it and it made just little difference in the first 1000 - 2000 Km. After that it was the same.-- This is encouraging that the new parts helped, with a noise change after only 1000 - 2000 Km, to me, that way more points to oil shearing (thinning) than to wear-in as  1000 - 2000 Km should not have changed anything mechanically in that short time frame. 

 

I agree on the cam chain replacement procedure. It is a massive job. Fortunately there is an alternative method which I have been using on other bikes. This guy made a video of that method on a F800-- That is why I mentioned "correctly" in my above post. I am sort of familiar with the master link cheat but as I have seen 2 bikes that was used on. One I don't trust as the master link pins were cracked during the peening. The other I never got to see the finial peening so haven't a clue on how that one looked. 

 

I have only installed one 800 timing chain & it was a winter project so I did it the correct way as the owner is a friend on mine & we ride WAY off road (20-30+ miles) into the back county with no way to get a recovery vehicle back in there if there is a chain failure.  

 

It seem that is not so uncommon for the F800 cam chain to get stretched and loose at low mileage-- Yes, that seems to be the talk but to me cam chains don't stretch, they can wear but actual stretching is kind of unheard of. The other thing I have found on the 700/800 bikes is cold engine piston rattle (piston slap) that a lot riders confuse with cam chain rattle. I have also seen a number of 800GS bikes have cold  drive chain rattle at ride-off as the chain can slap on the plastic swing arm protector in cadence to engine cylinder firing. 

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22 minutes ago, dirtrider said:

Yes, that seems to be the talk but to me cam chains don't stretch

 

:-) yes exactly. Although incorrect,  google search replies with most answers when this commonly used expression for the condition is used as search criteria 

 

How do you determine whether the cam chain is worn or not, particular to the F800? How much is to much? Just indicative like the amount of chain drop between cam sprockets like on the video form my previous post. Or maybe timing marks on cam chain sprockets when the crankshaft is locked at TDC like attached photo.

 

Just an idea, a test that I am considering. Measuring the correlation of crankshaft and camshaft signals with oscilloscope, comparing the measurements with old and new tensioner, cold vs hot, combining other tests .......

F800GS cam timing marks.jpg

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dirtrider
13 minutes ago, 14TLC said:

 

:-) yes exactly. Although incorrect,  google search replies with most answers when this commonly used expression for the condition is used as search criteria 

 

How do you determine whether the cam chain is worn or not, particular to the F800? How much is to much? Just indicative like the amount of chain drop between cam sprockets like on the video form my previous post. Or maybe timing marks on cam chain sprockets when the crankshaft is locked at TDC like attached photo.

 

Just an idea, a test that I am considering. Measuring the correlation of crankshaft and camshaft signals with oscilloscope, comparing the measurements with old and new tensioner, cold vs hot, combining other tests .......

 

Morning  Morning 14TLC

 

How do you determine whether the cam chain is worn or not?--- That is a darn good question. If you had a solid baseline on the engine as new then you could use cam gear alignment, or sensor trigger point vs crankshaft position, or even tensioner displacement to determine wear in the cam chain drive parts. This would be a pretty engine temperature dependent test as there is a lot of growth in the cam drive parts during engine heating.  

 

Even with the above, determining chain wear from chain guide wear, or cam sprocket wear (or all combined) would be difficult.

 

I haven't done much with the BMW 800 as far as cam chain wear growth is concerned as I only have a few 800 bikes that I work on or keep track of & those seem to only be a cold rattle issue so far. 

 

I do have 2 bikes in my group that have pretty good cold engine piston slap though. Good part is that the slap goes away as the engines warm up. 

 

By far my biggest concern on the 800 bikes (older 800 bikes anyhow) was stator failures while on trips or far into the back country. It is/was difficult to get the owners to spend the big money on the improved flywheel & stator parts kit. I had a 2012 800GS that never did fail a stator (I was always going to machine the flywheel for better cooling oil flow but never did) but I did install a linear voltage regulator very early in it's life & that is more than likely the reason it didn't fail a stator.

 

I have been meaning to make a cam chain displacement checking set-up from an old tensioner cap (drill the cap then thread the hole, then add an adjustable bolt). I made a similar cam chain displacement checking set-up for the old 600/650 KLR's & it works pretty good (can't tell chain wear from guide & sprocket wear but gives an idea on how much total wear (from first baseline measurement) we are dealing with.

 

 

 

 

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