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Surging problem


BeemerBerg

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My 2016 1200RTW seems to have a hard time maintaining a steady speed @ 30-35 MPH, 2nd gear (city driving speed). Feels like my old 1100Rt: trying to decide whether it wanted to 'go faster/go slower'.

Anybody else experiencing the type of low speed surging on their Wethead?

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Recent trip multiple gas stations across 4 states. I cam home with a bad tank of gas. I drained what I could into the garage 5 gallon can, ran another 40 miles and went and filled it here at home at my regular station. I still only took 5 gallons so I had 1.6 of bad gas left in the tank. StarTron at double dose, ran it 20 miles and it started acting almost right. I know it is water and the only cure is dilution by adding fresh gas and treating it with some type of gas treatment.

 

I hope you get it squared away.

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Bill_Walker

Are you sure that it's not you? I'm still getting used to my new-to-me '15, and I find that, especially in Dynamic mode, it's hard to hold a steady throttle over bumps. The throttle is very sensitive, and no matter how loose I try to keep my arms, I get some variation. What's worked best for me is bracing my throttle position with two fingers on the brake lever (where I keep them to cover the brake anyway).

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Bill_Walker
Are you sure that it's not you? I'm still getting used to my new-to-me '15, and I find that, especially in Dynamic mode, it's hard to hold a steady throttle over bumps. The throttle is very sensitive, and no matter how loose I try to keep my arms, I get some variation. What's worked best for me is bracing my throttle position with two fingers on the brake lever (where I keep them to cover the brake anyway).

 

I should perhaps add that I have not had this problem on any other bike, and I rode with a Throttle Rocker on my 1150RT and my V-Strom, which ought to exacerbate the effect. I think the throttle spring (rheostat spring, since it's ride-by-wire?) on the 1200 is very light.

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My 2016 1200RTW seems to have a hard time maintaining a steady speed @ 30-35 MPH, 2nd gear (city driving speed). Feels like my old 1100Rt: trying to decide whether it wanted to 'go faster/go slower'.

Anybody else experiencing the type of low speed surging on their Wethead?

 

Evening BeemerBerg

 

Well, some seem to do that. The worst ones that I have seen are the (WC) GS (I know of 2 that surge pretty bad at light throttle in lower gears)

 

I have a friend with a 2014RT that I can get to surge pretty easily but he never complains about it so rider sensitivity (or riding style) seems to figure into this also.

 

I do know of (not close riding friend though) a local 2015RT rider that was complaining of light throttle lower gear surging & claims that it went away after he had the cams retimed to BMW specs (I can't verify this as I didn't ride his bike before or after but he seems happier with the bike after the cam re-time)

 

If your dealer will work with you then you might be able to convince them to check your cam timing.

 

Make sure that you get it on record with your BMW dealer & if possible on record with BMW NA.

 

 

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Thanks for the quick replies.

I should mention that the bike only has 5000 miles-- so maybe I can get the dealer to check it out under warranty? I will try some Techron, but bike has behaved this way since birth.

DR mentioned cam timing. Interesting. How/why would the cams 'change'? Are they not fixed to to camshafts? Is this something I can check, or does it take special mojo?

Is this something a GS911 can help track down? (Trying to justify the $400 cost).

Dealers are 4 hours away (las Vegas) or 6 hours (salt lake city). ☹️

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The cams can move, there is a press fit that can change apparently.

 

I mentioned trying riding in "rain" mode. This makes a change in engine mapping and response. See what it does for you. I had trouble at first on my RT, and found that switching to rain mode in traffic smoothed it out a lot.

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The cams can move, there is a press fit that can change apparently.…

 

 

???

 

I consider myself reasonably knowledgable technically, but I have no idea what that statement means.

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The cams can move, there is a press fit that can change apparently.…

 

 

???

 

I consider myself reasonably knowledgable technically, but I have no idea what that statement means.

 

Afternoon Green RT

 

The cam drive gears are not keyed to the camshafts, they are a friction fit held on with tight bolts. There is nothing other than friction & tight bolt clamping to hold the cams in time with the crankshaft.

 

There have been a number of reports of cam timing issues on the 1200 (wc) engines, I'm just not sure if they are slipping position when in use or were not timed correctly at initial assembly.

 

It takes a special (expensive) tool to hold the cams in proper position while torqueing the retaining bolts but it looks like a person could make a simple checking tool to get a reasonable idea of the camshaft timing. (couldn't change it but might be able to check it)

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You're forcing the bike to operate in cruise control mode under less than ideal conditions: 35MPH in 2nd gear. Every little change in throttle position by the control is amplified in this situation. Just not designed for it. Plus driveline lash as already mentioned comes into play more.

Edited by bobbybob
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A cam gear that's NOT an actual part of the camshaft--on an engine with a sophisticated spark timing system that's accurate to a gnats ass-spinning at 7000 rpm for 100k + miles. So, if Fritz didn't get that gear positioned JUST RIGHT at the factory assembly line, and that little bolt Not torqued too tight--What could go wrong??

On a bike that's not designed to go smoothly in traffic @ 35 mph? NOT using cruise control in traffic.

I'm missing something here.

🤔🤔

 

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First there are three tools and four pieces to those tools. I see no way to replicate them at all. Even the spring loaded TDC tool is pretty sophisticated. You would never be able to make a cam tension tool to load the cam chain like it was running pumped up on oil. And finally the jig that fits over the two ends of the cam shaft is very precise and I do not believe you could make it.

 

They cost 290.00 bucks to own.

 

I just did this and it is not too big a deal with the tools.

 

My left was off a whole lot and my right was off a bit also.

 

The bolts are torqued to 65 Nm on the end of the cam shafts.

 

ADV rider is where I got my information and tool numbers and the procedure to use.

 

The cam shaft timing tool will fit on the end of the cams with the stock cam tension-er in. When you put the tool in it puts the correct pressure to simulate a pumped up cam tension-er and that is when you will see your timing off.

 

I am afraid a dealer will just through the jig on the end and tell you they are in time, when you need to use the cam tension tool to see timing correctly.

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The cams can move, there is a press fit that can change apparently.…

 

 

???

 

I consider myself reasonably knowledgable technically, but I have no idea what that statement means.

 

Afternoon Green RT

 

The cam drive gears are not keyed to the camshafts, they are a friction fit held on with tight bolts. There is nothing other than friction & tight bolt clamping to hold the cams in time with the crankshaft.

 

There have been a number of reports of cam timing issues on the 1200 (wc) engines, I'm just not sure if they are slipping position when in use or were not timed correctly at initial assembly.

 

It takes a special (expensive) tool to hold the cams in proper position while torqueing the retaining bolts but it looks like a person could make a simple checking tool to get a reasonable idea of the camshaft timing. (couldn't change it but might be able to check it)

 

Ah so. That is clear. Thanks DR.

Edited by Green RT
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It takes three tools and they cost 290.00 to own.

 

You are not going to make any of those tools. Well you could make a 8mm pin to find TDC in the inspection hole but you will play hell hitting that hole unless it is spring loaded to go in the TDC hole as it comes around, and it must screw into the inspection hole to be held strait to hit the 8mm hole.

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I think cam timing being off is chain stretch. It would explain how so many bikes I have read about on the 12K need the timing put back in.

 

I run the crap out of the bike 100+ every time I have it out. It has been to two dyno sessions for tuning. I just plain run it.

 

I never had any surging but did have issues getting use to the throttle. I put it in Rain for a bit and that helped. After that it never moves from Dynamic.

 

There is not a lot of settings for the throttle opening that I know of. You can set throttle position with a GS-911 but not much else I know of. I also do not know if throttle position is that same as throttle percent?

 

Curious if you get resolution and what that is.

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I think cam timing being off is chain stretch. It would explain how so many bikes I have read about on the 12K need the timing put back in.

 

I run the crap out of the bike 100+ every time I have it out. It has been to two dyno sessions for tuning. I just plain run it.

 

I never had any surging but did have issues getting use to the throttle. I put it in Rain for a bit and that helped. After that it never moves from Dynamic.

 

There is not a lot of settings for the throttle opening that I know of. You can set throttle position with a GS-911 but not much else I know of. I also do not know if throttle position is that same as throttle percent?

 

Curious if you get resolution and what that is.

 

Morning LAF

 

The few that I have seen out of time are more out of time between the 2 cams than

between the cams & crankshaft. (this would come from either slipping gear to cam

or not set correctly from the get-go)

 

If the cams are still close in time with each other but not in time to the crankshaft

then I suppose chain stretch could account for some or all of that.

 

But if the cams are out of time with each other then that isn't from chain stretch.

 

 

 

 

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Well I have to respectfully disagree. If the bolts are tight as mine were and I mean tight no way they turned.

 

Since they are chain driven I see that as the only way the move, chain stretch.

 

Not sure how you can determine which lobe is off, exhaust or intake? I could have put the alignment tool on either cam and it would have shown off. And the only thing they can be off to is the crankshaft as that is the reference TDC? And since it does not show out of time until the proper tension is put on the cam chain that leads me and the original author of this information to attribute it to chain stretch.

 

Of course I look forward to more information and thoughts from you as this is what forums are about.

 

As to being off from the factory I believe that but my heart of hearts hopes that is not the case.

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Well I have to respectfully disagree. If the bolts are tight as mine were and I mean tight no way they turned.

 

Since they are chain driven I see that as the only way the move, chain stretch.

 

Not sure how you can determine which lobe is off, exhaust or intake? I could have put the alignment tool on either cam and it would have shown off. And the only thing they can be off to is the crankshaft as that is the reference TDC? And since it does not show out of time until the proper tension is put on the cam chain that leads me and the original author of this information to attribute it to chain stretch.

 

Of course I look forward to more information and thoughts from you as this is what forums are about.

 

As to being off from the factory I believe that but my heart of hearts hopes that is not the case.

 

Morning LAF

 

You can disagree with me all you want, in the overall tilt of the

world that makes little difference.

 

But what you can't disagree with is physics.

 

As can be plainly seen in this picture the cams are solidly geared

together so chain stretch has NOTHING to do with cam to cam timing.

 

kxyRFKd.jpg

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Dirtrider, how hard is it to break loose the cam fastener, then loosen the gear? Concerned that it may be a tapered fit. Which can have issues coming loose. Sounds like you may have done this, just wondering as I may want to do this to my RT. Seems my fuel mileage isn't what it was and this could be a factor. Among others....

Edited by realshelby
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It is the cam chain, driving the cam chain gear, that drives the cams. You are really setting the cams to the cam chain drive gear at top dead center.

 

You do see that and understand that small gear in the center off the cam chain gear is what you are setting the cams to?

 

Not gonna fuss over it but gr8riden will tell you the same thing. What you are saying is that my cam gears would have been loose and slipped somehow. Trust me when I tell you all 4 were on tight and took the proper effort to break loose.

 

Edited by LAF
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It is the cam chain, driving the cam chain gear, that drives the cams. You are really setting the cams to the cam chain drive gear at top dead center.

 

You do see that and understand that small gear in the center off the cam chain gear is what you are setting the cams to?

 

I think there is a communication gap here. Not speaking for Dirtrider, but I think he would agree that setting the cam gear ( what drives both intake and exhaust cams ) to the correct position at TDC is the first most important check/adjustment. This measurement could be effected by cam chain stretch. BUT....after you have this gear in perfect position,you can still be out of time! Because the two cams are driven by a friction fit and from the same cam drive gear there CAN be misalignment. That is what Dirtride is saying with these two quotes "But if the cams are out of time with each other then that isn't from chain stretch." and "As can be plainly seen in this picture the cams are solidly geared together so chain stretch has NOTHING to do with cam to cam timing."

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If what you were saying is true then the cam gears and the cam shaft would have a reference for putting them together they do not! It is the use of these 3 tools that sets timing to the cam chain drive gear at TDC

 

1131_MODELLE_00_K50_R11148b_small.jpg

Edited by LAF
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There is a reference point. The machined flats on the end opposite the cam driven gear. As long as the cam lobes are pointed in the correct direction, these "reference points" will fit with the alignment tool. It looks like there is no "incorrect" way to install the cam driven gear, it just fits onto the cam while the cam and main timing gear are in the correct position and then is tightened in place.

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Dirtrider, how hard is it to break loose the cam fastener, then loosen the gear? Concerned that it may be a tapered fit. Which can have issues coming loose. Sounds like you may have done this, just wondering as I may want to do this to my RT. Seems my fuel mileage isn't what it was and this could be a factor. Among others....

 

Morning Terry

 

It's not difficult to break the cam gear fasteners loose but you RELLY SHOULD have, or make, a cam holding tool before doing so.

 

You need to hold the cams in alignment with each other & with the crankshaft while re-torqueing the cam gear bolts.

 

As I mentioned above it is not difficult to CHECK the cam timing (at least within operatable reason) but you will probably need to have (or make) a crank holding pin & some sort of cam holding tool to re-set the cam timing if it is found out-of-time.

 

I have spot checked a few that had starting problems or surging problems & found a couple being off (both still under warranty so I sent the owners to BMW for warranty cam re-timing)

 

I am going to start spot checking more as I do valve adjustments on them.

 

Pretty easy to spot check with homemade tools or just by eye.

 

I just start engine & run for about 10 seconds, or if spark plugs are out just crank until oil pressure is built. (this fills & pressurizes the cam chain tensioners)

 

Then remove spark plugs (you could probably do it without this step but it makes turning engine with rear wheel easier)

 

Then with trans in 6th gear rotate rear wheel (bump engine over) until cam lobes are facing out.

 

Then remove the timing hole plug & lightly bump the engine until the crankshaft timing hole is centered in the crankcase timing hole (I use a bore inspection light to see down in the timing hole)-- This is kind of the subjective part so you need to have a good eye for centering things & have a good straight-on viewing angle.

 

Once you are sure that you have the crankshaft timing hole centered in the crankcase timing hole then put a homemade (offset straight edge on both cam flats (opposite end from gears)

 

They should be on the same plane (ie both vertical)

 

I have used both an offset straight edge (bar stock with a notch cut out of one end) & used a small digital inclinometer & both seem to work acceptable. Probably not perfect but will sure show a gross cam timing issue.

 

You can refine the check a little more by bumping the engine until both cam flats are as close to being on the same plane as possible, THEN look in the timing hole to see how far off the crankshaft hole is in relation to the crankcase timing hole.

 

When I get a chance I am going to make a cam holding tool (very close to what LAF pictured) & make a crankshaft timing hole tool (I see no reason to spring load it as I can just hold pressure on the pin with my finger until it snaps into the crankshaft timing hole. (TDC & BDC use different sized holes)

 

I'm not sure I will make a cam chain tensioner as so far a little engine cranking has held the chain tight throughout my quick checks) --(I'll make one if I need to though) -- I presume the chain tensioning tool is more needed after an engine re-assembly as the tensioners would be pretty drained & lacking tension.

 

 

 

 

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I get what is being said now. The cam shaft does have the squares stamped on the other end of the cam shafts which does in fact show alignment to one another.

 

And yes you are setting the cams to one another with the jig that fits over that end of the cam shafts.

 

So what changes the relationship of the two cam shafts?

 

So YES it would appear the cam shaft gears have moved somehow. Or they are not set correctly at the factory.

 

My only issue with this is what keeps them from really spinning a bunch out of time?

 

And if it is a factory issue once you set them then they should not move again?

 

I will not know for 12K more but maybe someone can verify it sooner then me.

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Afternoon LAF

 

 

 

So what changes the relationship of the two cam shafts?--I have no idea, the couple that I have found had the cam to cam timing out a fair amount so they were either built that way or they slipped (I didn't check cam bolt torque so I have no idea if the bolts were properly tight)

 

So YES it would appear the cam shaft gears have moved somehow. Or they are not set correctly at the factory.--If the cam gear bolts are properly torqued & tight then that would more point to sloppy assembly.

 

My only issue with this is what keeps them from really spinning a bunch out of time? --Nothing, so IF the bolts are tight it would probably more point to poor original assembly. I haven't done enough (or actually done any) re-checks after a number of more riding miles)

 

And if it is a factory issue once you set them then they should not move again?--You should be able to tell us this in the future after your next re-check.

 

 

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There, I think we are all on the same page now!

 

I may just buy the tools. I can see how making a TDC/BDC tool would be easily doable. But one has to consider how much time it takes to make these tools and be precise.

 

I am hoping this is one of those things that once are set perfect, stay that way.....

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What you describe is accurate to a point but a few things bother me.

 

First the original question how do the cam shafts move out of time in respect to each other.

 

How do you know you have the cam chain to the pressure that simulated a fully running pumped up cam tensioner? Would they not start to leak down as soon as the motor is off and spinning the wheel to TDC especially since you need to check both sides?

 

The whole check is based on TDC AND the cam chain tensioner being at a set pressure.

 

As my photo shows the left side it was out according to the jig but the right side was out ever so slightly but still needed set. Would just sighting them or laying a strait edge across them show that. I know what you are saying as Jim's DVD shows that method for checking TDC on a valve check. However I would never trust it to cam timing.

 

Again me and my skill set I want the tools.

 

The Dealers DVD calls out for all three tools on camshaft replacement and timing checks so I do not believe for a second that the tools are for only building the motor.

 

I am not looking at a service DVD or a Haynes for these things I am looking directly at a BMW Motorrad Dealer DVD that covers all bikes and is what is used in every dealer shop.

 

While I respect your skills and knowledge I do not think you do anyone any favors by saying eying something like TDC on a crank, and running a bike to simulate cam chain tension is good practice except for a highly skilled mechanic like yourself.

 

I agree it might get you close enough to say yes they are out but I do not think it is accurate enough to set timing.

 

The TDC tool has a shoulder on it to the spring loaded pin. It looks like 3/8" That shoulder is the distance the crank sits in from the inspection hole after it is screwed into the inspection hole. I just do not see eyeing a accurate way to know you are at TDC.

 

Again I am old and do not have your skill set and I do not think many here do. IMHO buy the tools, show people how to use them in your clubs, have tech meets, but advocating for a approach that is not repeatable 100 out of 100 times accurately is not a good thing.

 

 

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Afternoon LAF]

 

First the original question how do the cam shafts move out of time in respect to each other.--I have no idea of how or when it happens but it does happen as I have found a few with out of time cams & yours seemed to be out.

 

How do you know you have the cam chain to the pressure that simulated a fully running pumped up cam tensioner? Would they not start to leak down as soon as the motor is off and spinning the wheel to TDC especially since you need to check both sides?--Experience & common sense. If you grab the cam gear & it moves then the chain is too loose. If the chain is tight then close enough for a basic check.

 

The whole check is based on TDC AND the cam chain tensioner being at a set pressure. --Yes, that is why I crank the engine to build oil pressure & tension the chain. Is it perfect? Probably not, is it close enough for a basic check? So far it seems to be.

As my photo shows the left side it was out according to the jig but the right side was out ever so slightly but still needed set. Would just sighting them or laying a strait edge across them show that.--From my experience the straight edge is pretty accurate as the cam flats are fairly long. Is it perfect? probably not, is it close enough for a quick check? Seems to be so far.

 

I know what you are saying as Jim's DVD shows that method for checking TDC on a valve check. However I would never trust it to cam timing. --If a person doesn't have the cam tools then it is a LOT more accurate than guessing at the cam timing by riding the bike.

 

 

While I respect your skills and knowledge I do not think you do anyone any favors by saying eying something like TDC on a crank, and running a bike to simulate cam chain tension is good practice except for a highly skilled mechanic like yourself.--I guess that is a personal decision. Is it perfect? heck no. Can it be used to find a grossly out-of-time cam or cams? SURE. In fact I have found a couple with this method.

 

I agree it might get you close enough to say yes they are out but I do not think it is accurate enough to set timing. --No, I NEVER said or suggested to SET the cam timing this way. In fact just the opposite as I said the cam tools (either BMW or homemade) are needed for proper re-setting. This method is just another tool to use to find grossly out of time cam or cams.

 

The TDC tool has a shoulder on it to the spring loaded pin. It looks like 3/8" That shoulder is the distance the crank sits in from the inspection hole after it is screwed into the inspection hole. I just do not see eyeing a accurate way to know you are at TDC.--Then you shouldn't try this method.

 

Again I am old and do not have your skill set and I do not think many here do. IMHO buy the tools, show people how to use them in your clubs, have tech meets, but advocating for a approach that is not repeatable 100 out of 100 times accurately is not a good thing.--Yes, I hear you-- Very same thing has been said many/many times about buying & using the special tools for setting the 1150 stretchy belt, or lining up the BMW clutch disk, or bleeding the BMW I-ABS brakes, or setting the 1100/1150 crown bearing preload. But somehow we have been able to overcome this & do all these operations without buying the special tools.

 

Again-- I'm not advocating doing ANY BMW work without understanding the requirements. If you require the special tools then by all means spend the money & buy them.

 

Most riders need a tire pressure gauge to properly set their tire pressure but most don't need a special tool (pressure gauge) to tell them if they have a real low or flat tire.

 

Bottom line here-- If a person doesn't feel confident in using anything said here in checking their cam timing then by all means DON'T USE IT.

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Do Not Use the information that flatly disregards BMW prescribed method of checking cam timing is really good advice.

 

I really think you need to get over yourself just a bit. While there is no doubt you know your mechanical ability, to advocate to others there is no need for these tools is just irresponsible and doing yourself and others a disservice.

 

If you believe in your heart that starting a bike, filling a oil filled tensioner with oil that has three holes in it, two around the bottom and one in the top, will keep a set and repeatable force even while pressure is being applied to it by spinning the motor by the rear wheel to TDC twice then you have way more faith then I.

 

Anyone who is doing their own service who can not spend 290.00 bucks for tools is defeating the purpose of doing their own work, doing it right according to BMW prescribed standards.

 

Rigging does not cut it for me. I worked in the trades for 25 years and close enough never worked out real well.

 

Everyone has choices. For the 22K plus I have invested and what I save not going to a dealer more then pays for tools I need. It seems you are willing to trust your eye and the forces of nature over buying tools and that is your choice.

 

However it appears you work on others bikes and I hope they are aware of your standards for doing work. Close enough was never good my entire life. Right and wrong, go no go, in or out, no gray areas of close enough were allowed.

 

I guess this goes to what others have said "the only thing cheap about a BMW is the owner".

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Afternoon LAF

 

I get the feeling that we are on different planets here.

 

I am not & never have advocated readjusting the cams without

proper tools.

 

I am just pointing out a quick & dirty home check of the basic cam

timing without buying expensive tools.

 

There are a number of riders that would have to ride many miles out

of their way just take their bike to the BMW dealer for warranty

repair then sweet talk the dealer into checking the cam timing.

 

The vast majority of riders are not going to buy $290.00 worth of,

probably one-time-usage, cam tools with their bike still covered

under BMW warranty.

 

I'm not suggesting anybody do anything with or about their cam timing,

I'm just suggesting an option if they are suspecting a gross cam timing

issue (so far I have caught 2 bikes that were out-of-time with this

method so it CAN work)

 

 

 

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Ok I must have reentered Earths Atmosphere.

 

I respect you for schooling me as I respect anyone with more education and experience. I live to learn even this late in life.

 

I really did take it as you advocated this as a proper way to set timing and be damned with BMW tools. Especially when you mentioned overcoming prior years services and checks.

 

I suffered through brake bleeding my LT's brakes and buying a ridiculous priced funnel to do it. Opening those ports on that ABS block in the right sequence sucked!

 

Sorry for blowing up but I do not take lightly misinformation being spread. I am not saying you did that but if a rookie wrench read your post and says bag the tools I can do this with a strait edge, pump up the tensioners, and then eyeball TDC through the inspection port that is truly a recipe for disaster.

 

I make the offer here as I have elsewhere if you are in the area you are welcome to come here and use the tools. If you are in the area and want me to come to your house I will bring the tools. If you are distance and will put me up I will come to you with the tools. If you want to host a Tech Session I will be there as nothing better then a group of people learning and sharing.

 

If you have done the valve check and are sitting at the valve check state, it would be a half hour tops to check and set the cam timing with the tools.

 

I make that offer because I am fortunate to be alive and to thank the people and the forums who have helped me over the years. I will pay it forward where I can.

 

Again I apologize for being surly and misunderstanding what you were advocating.

 

 

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OP here.

Sorry for starting this war.

But wondering: WHY? Why a 'press fit gear'? In a spinning, lubricated environment that depends on PRECISION TIMING for efficiency & a smooth running engine?

Seems that if that gear can randomly rotate a few degrees on it's shaft, all bets are off. Your valve shims could be within .00001, but if they aren't opening/closing at the right time, meaningless. Setting the valve TIMING should now be part of the valve gap procedure [step one]? If i have the dealer do the 12k, will THEY take the time to check valve timing, or not?

Sorry for fretting, but my previous BMW was one of those that had a final drive failure--when the 'press fit' hub 'spun' on its axis.

Not sleeping well tonight, thinking of spinning randomness.

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"In my case the left cams were off at 6000 miles when I checked them. At 12K they were in spec and required no adjustment. At 24K both left and right cams were slightly off so I corrected them as part of the valve check. In my experience the cams do not slip relative with the drive gear if the gear bolt is tightened to 65 NM as called for. There is a textured friction washer between the gear and cam that prevents slippage.

 

The change in timing is coming from cam chain stretch is a result of change in relative positions of the cam and crankshaft. It takes only a slight slight chain stretch to change the timing. You can see this effect if you don't adjust the tensioner tool correctly while the engine is locked in TDC. Cam chain stretch is normal wear in most engines. I am now checking the cam timing with every valve check, every 12K miles. The cams may only be off by a couple of degrees, but when adjusted correctly I can feel improved balance in the way the engine runs and starts."

This is the answer I got when I asked about cam timing and why it is off from gr8ridin.

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OP here.

Sorry for starting this war.

But wondering: WHY? Why a 'press fit gear'? In a spinning, lubricated environment that depends on PRECISION TIMING for efficiency & a smooth running engine?

Seems that if that gear can randomly rotate a few degrees on it's shaft, all bets are off. Your valve shims could be within .00001, but if they aren't opening/closing at the right time, meaningless. Setting the valve TIMING should now be part of the valve gap procedure [step one]? If i have the dealer do the 12k, will THEY take the time to check valve timing, or not?

Sorry for fretting, but my previous BMW was one of those that had a final drive failure--when the 'press fit' hub 'spun' on its axis.

Not sleeping well tonight, thinking of spinning randomness.

 

Morning BeemerBerg

 

You are looking at the negative side. Sure things can move if not assembled & torqued correctly. BUT!- the upside is the cam timing can be periodically checked & corrected if needed. A number of high end automobiles use the same (non keyed) cam timing gear retention without any issues.

 

The old BMW boxers had the same chain wear problems (actually had a front chain also) so over miles the cam timing would change a little or a lot (who knows). The big difference is on the older boxers there was no good way to see or measure the cam timing change so it was out-of-sight, out-of-mind.

 

On the older BMW boxer engines most riders had no idea if the cam timing was anywhere close, or changed over time, or stayed put. Nobody really cared except a few of us old timers that played with offset cam sprockets to change the cam timing to improve ridability in certain RPM ranges.

 

I think that over time the new cam gear retention will prove itself to be a good solid system but we might see a BMW mandated mandatory cam timing check at first run-in service then possibly another in the 50k range.

 

The thing that makes the new friction cam gear retention seem fragile is the tool to check/hold the cams is a precision fit so it kind of turns into a yes/no tool not a "within an acceptable range" measuring tool.

 

I presume that in the future we will see some custom cam holding fixtures (or even adjustable) that will change the intake or exhaust cam timing a few degrees to improve ridability in certain operating ranges. Or maybe BMW has variable valve timing coming in the future.

 

 

 

 

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I just moved from a 2014 Triumph Trophy that had the same basic cam gear design. It had 2 bolts (with Loctite) to hold the cam gears on and the same need for an alignment tool and a calibrated cam chain tension device (at over $200). The procedure for the Triumph required you to rotate the engine in order to loosen both bolts take the cam ladder off, sync the cams and then find TDC and reassemble the cam and ladder and the cam gears had the chain tied to them directly. Cost for the dealer to do this proper procedure as part of a valve adjustment? $1200 - $1500!

 

The BMW method and design is far superior.

Edited by AZgman
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VVT will be in the GSW in 2019 or so.

 

Have seen something in a German nagazine that was talking about it.

 

1250 Motor, VVT, TFT Screen.

 

When that makes it to the RT I am in. With those three things AND the already transmission updates, that would be enough to open the wallet and let the 15 RT go.

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Well going to collect some data. Monday will be doing a GSW and then later in the week a 16 RT. Interested in if they have out of time cams also.

 

More data points.

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