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Limecreek

Annual Service and Cam Alignment

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Limecreek

Started my annual service and found the cam timing a wee bit off that I corrected with the help of some BMW specified tools.

 

Cam alignment and chain tension tools.

166724099.jpg

 

Tool for finding TDC.

166724097.jpg

 

Cam chain tool in position.

166724102.jpg

 

Left side cams at TDC.

166724103.jpg

 

Cam alignment tool in place - cams slightly out of alignment.

166724104.jpg

166724105.jpg

 

Cam trigger sensor removed.

166724106.jpg

 

Crows foot to loosen the cam gear retaining nuts.

166724107.jpg

 

Adjusted and aligned.

166724108.jpg

166724109.jpg

 

Tighten cam gear nuts and install cam sensor trigger and align.

166724112.jpg

 

Remove chain tension tool and install cam tensioner with new washer.

166724113.jpg

 

Check the valves (all in spec), button up the bike and move to the next task.

166724115.jpg

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Highway41

How did you determine your cam timing was off? And any idea what caused it?

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Limecreek

The alignment tool is used to determine alignment. It is a go, no/go tool.

 

As for cause....the bike is too new for cam chain stretch so I would assume it came out of the factory that way. The adjustment was quite small.

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AZgman

I assume you did the right side as well? If so, did you move the cam tensioning tool over the the right side or did you just leave it on the left side?

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Limecreek
I assume you did the right side as well? If so, did you move the cam tensioning tool over the the right side or did you just leave it on the left side?

 

Yes - both sides. The tool slips over the cam fittings when aligned properly. It just a tool to check alignment and to hold the cams in place when tightening the cam gear nuts.

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MikeB60

Thanks for posting this. I just received the tools and am ready to check my cams at the 6000 mile service.

Edited by MikeB60

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Pappy35

Where did you buy these? Nothing like having the right tools for a job. Is there a service manual available that applies to the wetheads?

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Brian Louw
Where did you buy these? Nothing like having the right tools for a job. Is there a service manual available that applies to the wetheads?

I have just started looking at this for my 2016 R1200GSA and found these at ASCYCLES. Scroll down to find the other two tools. I haven't ordered them and I suspect you could manufacture the TDC tool and jig, but the Cam Tensioner tool seems to be more tricky and is required to get the correct tension on the cam chain to set the valve timing.

The service DVD is also available at ASCYCLES and I just received mine. They were on backorder for a while.

 

 

Cam adjustment tools

 

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AZgman
I assume you did the right side as well? If so, did you move the cam tensioning tool over the the right side or did you just leave it on the left side?

 

Yes - both sides. The tool slips over the cam fittings when aligned properly. It just a tool to check alignment and to hold the cams in place when tightening the cam gear nuts.

 

 

I was asking about the cam chain tensioning device, not the alignment tool.

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Mudman

The cam chain tensioner tool must be used on each side to get accurate cam timing. Each side uses a separate cam drive chain.

 

Complete the cam timing check/adjust on one side, turn the engine crank two revolutions to return to the adjustment point, recheck your work

Remove cam tensioner and replace the tensioner piston and plug with a new crush washer.

 

Repeat this process on the other side with the tensioner tool installed and repeat the same process for cam timing.

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Limecreek

The only difference in the procedure, from the left to the right, is the cam sensor trigger - it only exists on the left side and must be removed to access the exhaust cam retaining nut.

Edited by Limecreek

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markgoodrich

I have people for that.

 

Oh, wait, Greg, you're my people!

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realshelby
I have people for that.

 

Oh, wait, Greg, you're my people!

 

Are you saying there will be a "Cam alignment Tech Days" at the Limestone Ranch?

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PadG
The alignment tool is used to determine alignment. It is a go, no/go tool.

 

As for cause....the bike is too new for cam chain stretch so I would assume it came out of the factory that way. The adjustment was quite small.

There is a good thread on this issue in the BMWLT forum, and Lee (LAF, also a member here) had done an excellent job of keeping statistics on how many of the "new" wetheads that he had taken apart had the cam timing off, from the factory!

 

http://www.bmwlt.com/forums/rt-series/169458-12k-cam-timing.html

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AndyS
Started my annual service and found the cam timing a wee bit off that I corrected with the help of some BMW specified tools. .... move to the next task.

What year is your bike? I am surprised to see the valve timing so far out!

Lee (LAF) on the LT forum has also found some to be out. I was curious to know why this is not being picked up at the relevant BMW Dealerships during their servicing.

 

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Limecreek
The alignment tool is used to determine alignment. It is a go, no/go tool.

 

As for cause....the bike is too new for cam chain stretch so I would assume it came out of the factory that way. The adjustment was quite small.

There is a good thread on this issue in the BMWLT forum, and Lee (LAF, also a member here) had done an excellent job of keeping statistics on how many of the "new" wetheads that he had taken apart had the cam timing off, from the factory!

 

http://www.bmwlt.com/forums/rt-series/169458-12k-cam-timing.html

 

Awesome - reading it now. I had not see this before.

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Limecreek
Started my annual service and found the cam timing a wee bit off that I corrected with the help of some BMW specified tools. .... move to the next task.

What year is your bike? I am surprised to see the valve timing so far out!

Lee (LAF) on the LT forum has also found some to be out. I was curious to know why this is not being picked up at the relevant BMW Dealerships during their servicing.

 

2016 MY Andy and the timing really was not that far off.

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Limecreek
I have people for that.

 

Oh, wait, Greg, you're my people!

 

Are you saying there will be a "Cam alignment Tech Days" at the Limestone Ranch?

 

 

Hmmmm. Could be.

 

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LAF

There seems no rhyme or reason as to cam alignment or cam position sensor alignment.

 

I think I am at 11 or 12 now and there seems to be no correlation to model, RT, GS, GSA, or year.

 

I do know that the cam position sensor is the most noticeable if it is out. In the GS I follow for thousands of miles, his was way off and when we set it in place his starts became instant. No hesitation or false starts any longer like he was experiencing.

 

The cams being out do not show the same good results that are seen and felt.

 

I do suspect that it shows up in improved gas mileage and performance that can not be perceived by seat of the pants.

 

As to why it is not picked up more often dealers just do not check cam timing. You need to ask and you may get a blank stare. The thing is if you are in for a valve check a cam check takes like 5 mins more. If they need adjusted it is uninstalling a cam chain tensioner, installing a cam chain simulator, and using the alignment tool over the end of the cams.

 

I have had people from all over the country stop here in PA for me to check their cams and we check valves while we are there as it takes only a few mins more.

 

To me if something is supposed to be in a spec I want it there.

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AZgman

While my cams were only slightly out of phase, my bike starts noticeably faster than before. It used to always start with a pop and now it just lights up.

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LAF
While my cams were only slightly out of phase, my bike starts noticeably faster than before. It used to always start with a pop and now it just lights up.

 

Well since you need to remove the cam position sensor on the left side to adjust the valve I wonder if it was off and then put back on in the correct position?

 

Regardless cams should be adjusted to spec using the tools. IMHO it is another quality control issue as there is no way for cams to "slip" or jump out of time, or because of the cam chain stretching. Since the two cams and the cam chain are connected by three sprockets or gears, no way for cams to jump out of time. I do not know for sure but I see no way once cams are aligned for them to ever be out again. If one I did comes back in 12K and is out I will for sure eat crow.

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92Merc

LAF, you wouldn't happen to be going to the Un-Rally in SD next summer? I would love to see the whole process in person.

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LAF

I am going to Iowa for the National.

 

Since it is not really riding country I may do some there.

 

 

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fastlarry

Why would cam timing ever change once it is set? and correctly one would hope.

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PadG

Cam timing shouldn't change until you get some stretching in the cam chain, and that could take a while.

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realshelby

Cam chain stretch isn't the only factor with the Wethead. Since you can loosen the cam drive gear to adjust it, I assume it could move on its own. More likely they are just not adjusted perfectly when built. The cams are gear driven from a gear that is turned by the cam chain. Meaning the two cams should never be out of proper phase. But, apparently some are.

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Limecreek
Cam chain stretch isn't the only factor with the Wethead. Since you can loosen the cam drive gear to adjust it, I assume it could move on its own. More likely they are just not adjusted perfectly when built. The cams are gear driven from a gear that is turned by the cam chain. Meaning the two cams should never be out of proper phase. But, apparently some are.

 

Cam chain stretch on this bike over time should be negligible. And my guess is once timing is properly set it will not change by very much. I'll check again in 12K miles.

 

166724110.jpg

 

As for detecting a performance gain as a result of the adjustment? Can't say I've noticed a difference. I have noticed the fueling flat spot I had around 7K is gone, but I am attributing that to the software update I paid for 2 weeks ago.

 

This most recent generation of the boxer motor is really amazing - powerful, smooth, spins up quickly and a more powerful version is in development.

Edited by Limecreek

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FlyingFinn

I did the same job on my GSA last month. At 12K miles all the valve clearness were still well within range, but the cam timing was slightly off on one side. Just like yours, the tool didn't quite fit, so out came the crowfoot.

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LAF

With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

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PadG
With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

Tensioner will just maintain tensions so that the chain don't skip a tooth, if the slack is excessive (as in no tensioner installed). When the chain stretch, the total length of the chain grows, and that is how the timing can change. Sure, the change will be a function of how much the chain has stretched.

 

No arguments (as you already know) about the timing being off from the factory.

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Limecreek
With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

Tensioner will just maintain tensions so that the chain don't skip a tooth, if the slack is excessive (as in no tensioner installed). When the chain stretch, the total length of the chain grows, and that is how the timing can change. Sure, the change will be a function of how much the chain has stretched.

 

No arguments (as you already know) about the timing being off from the factory.

 

The constant is TDC. With some stretch I can see the cam position slightly off as it relates to the piston position. Still do not believe I'll make the adjustment again in the next 70K miles or so - or at least I hope I will not have to.

 

Edited by Limecreek

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PadG
With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

Tensioner will just maintain tensions so that the chain don't skip a tooth, if the slack is excessive (as in no tensioner installed). When the chain stretch, the total length of the chain grows, and that is how the timing can change. Sure, the change will be a function of how much the chain has stretched.

 

No arguments (as you already know) about the timing being off from the factory.

 

The constant is TDC. With some stretch I can see the cam position slightly off as it relates to the piston position. Still do not believe I'll make the adjustment again in the next 70K miles or so - or at least I hope I will not have to.

With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

Tensioner will just maintain tensions so that the chain don't skip a tooth, if the slack is excessive (as in no tensioner installed). When the chain stretch, the total length of the chain grows, and that is how the timing can change. Sure, the change will be a function of how much the chain has stretched.

 

No arguments (as you already know) about the timing being off from the factory.

 

The constant is TDC. With some stretch I can see the cam position slightly off as it relates to the piston position. Still do not believe I'll make the adjustment again in the next 70K miles or so - or at least I hope I will not have to.

Not saying that you have to make adjustment, even at 70k. All that I am saying is that the thing that will affect cam timing is the so-called chain stretch (nothing actually stretches, but the chain will increase in length from use). Whether you need to make any adjustment at all is a function of how much the chain stretches, and I am fairly sure that nobody here can answer that question. The other unknown question is how much can the cam timing be off before it matters? Lee might have some ideas of that, since he has the hands-on experience with multiple wetheads. Having the adjustment slipping is a low probability, IMHO, but again Lee will be the best person to answer that from actual experience rather than just guessing! :)

 

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Yeeha! Stephen
I have people for that.

 

Oh, wait, Greg, you're my people!

 

Are you saying there will be a "Cam alignment Tech Days" at the Limestone Ranch?

 

 

You getting a petition up to have Greg do another "Austin Texas Tech Daze" ?

 

http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=424372&page=1

 

Where do I sign?

 

Yeeeeeha!

 

ps: make sure there's a follow-up ride scheduled for the following day!

 

108304149.jpg

 

108304192.jpg

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Yeeha! Stephen

If you can find the #34, Spring 2017, issue of BMW Motorcycle Magazine, it has a nice photo article similar to Greg's and shows cam removal and shim adjustments. Also give the part #'s for the special tools BMW sells for the job.

 

http://bmwmcmag.com/shop/bmwmm34/

 

=8-)

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LittleBriar
If you can find the #34, Spring 2017, issue of BMW Motorcycle Magazine, it has a nice photo article similar to Greg's and shows cam removal and shim adjustments. Also give the part #'s for the special tools BMW sells for the job.

 

http://bmwmcmag.com/shop/bmwmm34/

 

=8-)

Stephen, Thanks for the tip. I ordered the issue and also started a subscription. Looks like a nice magazine. Surprised I hadn't seen it before. Does the article you mentioned include adjusting the cam sensor and cam timing?

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Limecreek

Could happen - just depends on my travel schedule in Feb/March. Not sure how much interest there is these days, but they were fun back in the day. :-)

 

Picture from the first one I held all the way back in 2003.

22943131.jpg

 

One in the middle 2009 - best attended.

108304162.jpg

108304207.jpg

108304160.jpg

 

And the final one back in 2012.

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140944234.jpg

140944210.jpg

Edited by Limecreek

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realshelby

I made the 2012 Hottern' Hell Tech Daze! My second one. Maybe I ran everyone off?

 

Anyway, does the cam timing check have to be done on a cold engine? That might complicate doing them in a "tech daze" setting. Unless we do them Tuesday or Wednesday of this week..........

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LAF

I do not think heat has any bearing on cam alignment check, Really can think of no reason it would.

 

Thing is it is nice to check the valves while you are there so in that respect it would.

 

However I have held a garden hose on a few bikes in the center of the front of the motor, then the rear of the motor, and then the jugs after a time and the motor was cool enough in a hour or so to check valves. We set a large fan in front of them did the cam check and then the valves and the motor was cool to the touch.

 

 

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LAF

So did my new 17 GS today at 56 miles.

 

All was well and no issues at all with cam timing.

 

Have to say the TDC tool really snapped into TDC on this one. I mean it was buried and really snapped when it found the hole.

 

Maybe they are getting the hang of this stuff

 

 

Of note on the valve check I was not real happy but we will see after we get some miles on it.

 

However since the motor wears tight my valve setting don't bode well for me.

 

ALL seem tight to me but as they say in spec is in spec,

 

Here that is:

L

F Intake 10 R Intake 11

F Exhaust 34 R Exhaust 35

R

F Intake 14 R Intake 13

F Exhaust 34 R Exhaust 35

 

Couple have no room so we will see. I am sure with the shim kit I have I can get through it when it needs it.

 

So the Recap:

15 RT 12,000 miles, Left off real bad, right off also. Cam sensor on.

16 GS 12,000 miles, Right side off pretty well and left side off. Cam sensor way out. Adjusted

16 RT 6000 miles, Right dead on, Left off ever so slightly, Adjusted. Cam Position Sensor on.

16 RT 12,000 miles, Dead on both sides. Cam sensor on.

15 GSA 12,000 Miles, Dead on both sides. Cam sensor on.

14 RT 18,000 Miles , Dead on both sides. Cam sensors on.

14 RT 13,000 Miles, Dead on both sides. Cam sensor on.

15 RT 87,000 Miles, Dead on both sides. Cam sensor was off. Adjusted

16 GSA 1,688 Miles Right dead on. Left off ever so slightly, Adjusted. Cam Position Sensor on.

17 GS 56 Miles Dead on both sides Cam Position Sensor right on.

 

That's my story and I am sticking to it.

 

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Limecreek

Just as a final follow-up regarding performance gains as a result of the cam alignment - there is not any detectable (power/smoothness) or measurable (gas mileage) difference from my POV.

 

 

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LAF

No the cams would have to be off huge to notice a difference.

 

That said if the cam position sensor was off it will induce hard starts. Proofed this out 2 times now and once with the friend I ride thousands of miles a year with. His GS was way off. It would do the false start on the first button push and then start fine on the second push. Once we brought his cam position sensor into range it started with authority first push every time. I think if the cams are out it would be long term as far as gas mileage, and performance that would only show on a dyno.

 

However on is on, and with the alignment jig it is either in time or out of time. I want mine in time no matter how small the noticeable benefit.

 

This is a worthwhile maintenance procedure that IMHO should be done once to every bike to see what is what.

 

I guess really mechanically inclined guys could use the tools to advance timing or retard timing to achieve performance results. You would just need to figure out a way to degree the cams to get an exact setting. I think one could make a degree wheel for the end of the cam lobes to do this.

 

After running a Power Commander on my RT and 2 Dyno tunes there really is not a lot more power to be had in these motors. However these are a very lean running motor so fuel does help in areas of the fuel map where it is exceptionally lean.

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Lone_RT_rider
With three gears connecting the cams and cam chain I see no way chain stretch could make cam timing off. I mean after all that is what a cam chain tensioner is for. If you look at the pics you will see three gears it would have to jump a tooth to come out of time with each other.

 

I believe they are not set correctly from the factory.

 

Like I say if over the years I get another back that I did and it has moved, then I will need to step back and think about this in a different way.

Tensioner will just maintain tensions so that the chain don't skip a tooth, if the slack is excessive (as in no tensioner installed). When the chain stretch, the total length of the chain grows, and that is how the timing can change. Sure, the change will be a function of how much the chain has stretched.

 

No arguments (as you already know) about the timing being off from the factory.

 

Some thoughts on why the cam gear has adjustability at all.

 

1. Even though the gears are precision form (or machined) parts, there is a bit of variability in the overall system that is used to turn those cams. The one part believe it or not that has the most variability is the chain. Every link has multiple components that can cause that chain length to vary. If this was a gear drive cam, my guess is that it wouldn't have any adjustabilty for a factory install. I know that There are V8 car gear drives that do have adjustability for varying cam timing, but that's usually an aftermarket application with a single cam meant for "pre-timing" the engine.

 

2. There is a manufacturing process of some sort that requires that they have to flexibility to assembly the cams and cam drive assembly in such a way that it drives variability in the final assembly process. Don't laugh, in 26 years in engineering I have seen worse rational used for this type of thing. It might have been a cost driven decision where adding the cam adjustment at some point in the assembly process was less costly than integrating a design that was more assembly friendly. Once again, these kinds of decisions get made every day based on costs and assembly ergonomic decisions.

 

Just my thoughts....I may be completely off. :)

 

Shawn

 

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LAF

I still do not understand this.

 

If you have three gears meshed together as we do. Intake, Exhaust, and the cam chain shaft. Those three gears are meshed or indexed together. You then have a sprocket on the other end with a chain driving them. How can the chain getting loose change the mesh of 3 gears? It can make the chain droop or clatter if the cam chain tensioner can not take up the slack but I see no way it can change the indexing or mesh of those three gears?

 

What am I missing?

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AndyS

The 3 components meshed together will not change.

However what I think Shawn is saying is that the chain can stretch (minutely) and so the relationship between the crankshaft and the camshafts could start to 'lag'....fractionally and therefore require resetting of the 3 meshed together components.

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PadG
I still do not understand this.

 

If you have three gears meshed together as we do. Intake, Exhaust, and the cam chain shaft. Those three gears are meshed or indexed together. You then have a sprocket on the other end with a chain driving them. How can the chain getting loose change the mesh of 3 gears? It can make the chain droop or clatter if the cam chain tensioner can not take up the slack but I see no way it can change the indexing or mesh of those three gears?

 

What am I missing?

Lee, the meshed gears will not change position over time, but you need to look at the chain drive! As many have pointed out, cam timing is the relative position of the over-head camshafts to the piston position, in direct sense, of the engine's crankshaft, in the indirect sense. Both are the same. In any chain-drive, you have a drive gear and a driven gear. In our case, the drive gear is tied to the engine's crankshaft, while the driven gear is tied to the over-head camshaft. In any chain drive, the power, or motion, is transmitted by a gear tooth pulling on a chain roller at the drive side to pull the the driven gear tooth of the driven gear by another roller along the chain's length. In our application, we are interested in maintaining a very fixed rotational relationship between the two gears. Therefore, the slack must be maintained at some tension, or the driven gear can flop around with respect to the drive gear. That is the obvious one, and thet's why there is a chain tensioner in the system.

 

Now, what you seem to have missed is the fact that over time, the chain's bushings and pins will wear, causing what people call "stretch" in that the overall length of the chain will increase from the wear, and the timing will be affected. How so, you ask? Well, think of the ideal situation, when the chain is new, and imagine the chain being stretched between the drive gear and the driven gear at a standardized tension. You will see that there are "x" number of links of chain in between the two gears, and you need to note that the average "pitch" between the rollers of the links are very uniform and relatively precise. Now, just freeze this picture, then imagine if that chain is suddenly worn, so that the mean pitch distances are larger than the new chain. What do you think happen then? The chain tension between the two gears suddenly disappear, and the drive gear will need to rotate a little to take up the slack and restore the tension, which means that it will lose the rotational relationship to the driven (cam) gear, and therefore your cam timing will be a little off!

 

Phew......:)

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LAF
I still do not understand this.

 

If you have three gears meshed together as we do. Intake, Exhaust, and the cam chain shaft. Those three gears are meshed or indexed together. You then have a sprocket on the other end with a chain driving them. How can the chain getting loose change the mesh of 3 gears? It can make the chain droop or clatter if the cam chain tensioner can not take up the slack but I see no way it can change the indexing or mesh of those three gears?

 

What am I missing?

Lee, the meshed gears will not change position over time, but you need to look at the chain drive! As many have pointed out, cam timing is the relative position of the over-head camshafts to the piston position, in direct sense, of the engine's crankshaft, in the indirect sense. Both are the same. In any chain-drive, you have a drive gear and a driven gear. In our case, the drive gear is tied to the engine's crankshaft, while the driven gear is tied to the over-head camshaft. In any chain drive, the power, or motion, is transmitted by a gear tooth pulling on a chain roller at the drive side to pull the the driven gear tooth of the driven gear by another roller along the chain's length. In our application, we are interested in maintaining a very fixed rotational relationship between the two gears. Therefore, the slack must be maintained at some tension, or the driven gear can flop around with respect to the drive gear. That is the obvious one, and thet's why there is a chain tensioner in the system.

 

Now, what you seem to have missed is the fact that over time, the chain's bushings and pins will wear, causing what people call "stretch" in that the overall length of the chain will increase from the wear, and the timing will be affected. How so, you ask? Well, think of the ideal situation, when the chain is new, and imagine the chain being stretched between the drive gear and the driven gear at a standardized tension. You will see that there are "x" number of links of chain in between the two gears, and you need to note that the average "pitch" between the rollers of the links are very uniform and relatively precise. Now, just freeze this picture, then imagine if that chain is suddenly worn, so that the mean pitch distances are larger than the new chain. What do you think happen then? The chain tension between the two gears suddenly disappear, and the drive gear will need to rotate a little to take up the slack and restore the tension, which means that it will lose the rotational relationship to the driven (cam) gear, and therefore your cam timing will be a little off!

 

Phew......:)

 

 

Got you and understand this whole

relationship.

 

However the cam chain tensioner is supposed to be taking this slack out correct?

 

And the cam chain tensioner tool has no idea that your cam chain is stretched, as it applies a specified tension on it?

 

So the TDC tool finds the hole on the flywheel. Then you applied a specified tension to your cam chain regardless of how stretched it may be?

 

Then you adjust your cams if you need to?

 

Then you are back to a stretched chain with the slack being taken up by our hydraulic lifter?

 

What changed or what did we change?

 

As many of these I have done I see them as a manufacturing error and not a wear issue?

 

The bike with 88K was right on, so I assume it got put together correctly, and did not suffer any wear over 88K?

 

You and I have had this conversation before and while I do understand what you describe as far as engine operation, I am inclined to believe this is a manufacturer error.

 

 

 

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Limecreek

Lee your argument is chain stretch is taken up by the tensioner and maintains the proper cam position as it relates to piston position. This all assumes it was set up correctly when the engine was assembled.

 

From my POV there will be a point where the tensioner cannot take up enough stretch to maintain the correct cam position to piston position. However, I cannot believe we are experiencing significant chain stretch in 12K miles or 8K in my case. So I believe it was off at assembly which brings us back to the point Shawn made.

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AndyS
Lee your argument is chain stretch is taken up by the tensioner and maintains the proper cam position as it relates to piston position. This all assumes it was set up correctly when the engine was assembled.

 

But it doesn't. The Cam Chain tensioner is on the non drive side of a chain run and has nothing to do with maintaining proper cam position. It is there to stop chain 'slap' and to take up wear. The timing aspect does change, but that is where your second point is right. The amount of stretch at 8 or even 12K miles in insignificant and so very likely it is incorrectly set at build.

 

From my POV there will be a point where the tensioner cannot take up enough stretch to maintain the correct cam position to piston position. However, I cannot believe we are experiencing significant chain stretch in 12K miles or 8K in my case. So I believe it was off at assembly which brings us back to the point Shawn made.

 

Most vehicles historically didn't have any adjustment to compensate for chain stretch because it is so minute. However, IF it can be adjusted to the correct position to compensate, then it SHOULD be.

 

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realshelby

I think the missing point here is chain pitch. The distance between the centers of the rollers. Chain wear between the drive ( crankshaft ) and driven ( camshaft ) is not made correct by the tensioner. It cannot change chain length. All the chain tensioners do is keep the slack in the chain from slapping back and forth. Tensioners are on the return side of the process. Cam chains are not known to stretch much. They live in an oil bath environment and actually have little load on them. I cannot see chain stretch as a factor in cam alignment in a bike without high mileage. Don't know what that mileage might be, but few are there yet is my guess.

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AndyS
;) I think we both say the same thing!

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