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Discussion Starter #1
I've become aware in the past week that my AN650K7 (exec) CVT/tranny sounds a little more noisy than previous. It'd always been real quiet, but one morning when I started it to go ride to work or wherever I was surprised to here a louder than normal tranny sound.

The best way I can describe it is as similar to the "diesel-ing" sound my AN650K3 (exec) in NZ has - which is normal for that year. The K7 has always been much quieter, until the last week or so. Aside from the sound which has been somewhat disconcerting, there has not been any changes in performance or function when riding, oh aside from I noticed that the green "D" light seems a little like it's pulsating/flickering, which is not something I noticed before - whether it existed or not. I'm sure many here can attest, when one goes looking for faults, one finds more of them whether they are real faults or otherwise. Medicine and healthcare is a bit like that at times. I occasionally flick between D and M modes, especially when I want to coast down mountain roads of which there are many of here. If I intend to let the scoot "freewheel" like in neutral down a long mountain descent I always stop the scoot completely first, then engage M and usually just coast down. Most of the time speeds are kept below 30-40km/h. When I want to engage D again, or otherwise ride off in M mode, I always come to a complete stop first before motoring off. This is something that I've been doing for about 8 months or so. I did try to find any information about whether this freewheeling approach might do harm to the CVT/tranny - but never found anything specific or that could lead to a logical consensus. So I'm open to some logical discussion or considered opinion.

I'm always pretty easy and deliberate on the throttle, and hardly if ever WOT on any of my maxi scoots, or other moto's for that matter. But I did buy the K7 second hand/used with an indicated 5000km, and I've added another 25000km to that.

I've just changed all the fluids (engine, tranny, rear drive), oil filter and rear brake pads as part of a half day service I did at home in my garage here in mainland China within the past week/fortnight. I didn't check the CVT filter though, as planned to do that next weekend when I plan to fit a new front tyre. Just did the rear tyre 3000km ago.

Any ideas, or suggestions?
 

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As expected, after installing the Polish adapter, the next-lower tier of sounds became audible on my K4 with 19k miles. The most noticeable is a "diesel-like" tick which seems to be loudest on the left side near the alternator housing. I'm not sure whether it's ticking at engine speed or CVT speed but it does sound slower than engine. Every now and then I think I see a slight flickering of the lamps in my peripheral vision while riding, but when staring directly at them they appear very steady (which of course I don't do for more than a second at at time).

The "tick" is pretty quiet, the only time I notice it is when I have the tupperware off and my head on the ground next to the drive train. I wonder if it's the little return oil pump for the clutch housing? Not sure if that's a pulsating- or continuous-flow design though.

A mystery.
 

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BTW, your D > M shifting style is interesting, I do it on the fly when at steady speed, never bothering to come to a complete stop. The only issue is when below about 40mph going from D to M, the CVT will try to downshift so one has to mash the UP button very quickly after hitting the D<>M button.
 

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Discussion Starter #4 (Edited)
BTW, your D > M shifting style is interesting, I do it on the fly when at steady speed, never bothering to come to a complete stop. The only issue is when below about 40mph going from D to M, the CVT will try to downshift so one has to mash the UP button very quickly after hitting the D<>M button.
Just to clear any confusion about the changing from Drive to Manual or vice-versa. When I ride normally, I sometimes swap between either mode, but do so bearing in mind the speed and revs the engine is at when I'm looking to change from D to M. As you state, if changing from D to M is done at less than an opportune engine speed then this can cause the engine/CVT to be placed into to higher gear. So I'm fairly careful with that. Truth be told, I'm probably like most riders of the big Burgman650, leave it in D most of the time. The most common time I'm shifting between D and M is when I'm up near 90-100km/h and plan on being around the speed for a period of time and want to take advantage of the overdrive gear which generally doesn't kick in until a steady-ish 110km/h or so is sustained when using D mode.

The stopping to select between D - M, or back to D mode is only when I'm allowing the CVT to freewheel (like a neutral) in M mode down mountain roads. I do a lot of mountain riding, and there are plenty of opportunities to allow a bike to coast down the mountain roads in neutral. Naturally this can't be applied to scooters most of the time since they don't have a neutral. The Burgman650 does in some respects have a type of neutral when below 20km/h in either D or M modes. In D mode, when the scoot is allowed to freewheel it will do so up to around an indicated 20lm/h + or -. Once up around that speed or higher the CVT kicks in etc. If one selects M mode this changes. Select M mode on a slope, allow the scoot to freewheel on descent and the scoot will freewheel and keep building up speed as long as there is a slope to do so on. At no time in M mode does the CVT kick in when freewheeling, unlike when in D mode.

My usual method is, when I get to a descent I will often switch between D to M mode a very slow pace pretty much at a speed where the CVT disengages anyway, thus M mode will often result in the scoot starting to freewheel. Sometimes I will do this after coming to a complete stop beforehand. When the freewheel is over e.g. back down on a flat section, I will make a complete stop or pretty close to it, and then select back to D mode again. Hope this clarifies my use of D and M and the use of coming to a complete stop. I only do so when I'm allowing the tranny to freewheel, which is when I'm riding mountain routes.

It has worked well. But I don't do it all the time, on all my mountain rides which are at a minimum several times a week. The engine braking when in D mode also is a handy feature if one has learnt how to feather the throttle, to make it work well. I like it, and doing so saves on brake pads etc.
 

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Discussion Starter #5
As expected, after installing the Polish adapter, the next-lower tier of sounds became audible on my K4 with 19k miles. The most noticeable is a "diesel-like" tick which seems to be loudest on the left side near the alternator housing. I'm not sure whether it's ticking at engine speed or CVT speed but it does sound slower than engine. Every now and then I think I see a slight flickering of the lamps in my peripheral vision while riding, but when staring directly at them they appear very steady (which of course I don't do for more than a second at at time).

The "tick" is pretty quiet, the only time I notice it is when I have the tupperware off and my head on the ground next to the drive train. I wonder if it's the little return oil pump for the clutch housing? Not sure if that's a pulsating- or continuous-flow design though.
A mystery.
The tick might be the cam chain or the tensioner?
My K3 often has a flicker to the headlights, it's usually related to a change in voltage demand, like when the CVT is shifting, or else if the radiator fan is kicking in, or similar electrical demand. The K7 does this too from time to time, but it's not as frequent nor as noticeable when compared to the K3. It's the "D" mode light that I have become aware of that flickers that I'm fairly certain didn't really flicker before. It's not a flicker that makes the D light really like it's going to go out but rather a flicker like there is a voltage drop. Bike starts normally, no evidence that the battery is straining etc. Might be nothing... time will tell.
 

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OK now I understand, you let the clutch disengage and then coast downhill in M. Haven't tried that, most of my driving is on our very hilly roads (mountain foothills) on which I never get a long enough downhill run to try the "neutral" coast. Next long ride I'll look for a downhill run to practice it. The most important thing of course would be NOT to advance the throttle at all, yikes that could be extremely ugly if the clutch engaged at 110km/h!

I put my ear way forward on the drive train and the engine itself is sublimely quiet, no valve noise at all ... which now has me worried that they don't have enough clearance :-(
 

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I don't give much thought to when I switch from D to M.. I get on the 4 lane.. get up to speed (usually around 75 indicated on the speedo), swiitch to M , and then put it in 6th gear. I keep it there and my speed varies between 68 to 94 indicated in 6th gear, but when approaching my exit, I switch to D mode for better engine braking and acceleration when I get off the exit.. I am always moving when switching between the two.. why do it any other way?
 

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Discussion Starter #8
OK now I understand, you let the clutch disengage and then coast downhill in M. Haven't tried that, most of my driving is on our very hilly roads (mountain foothills) on which I never get a long enough downhill run to try the "neutral" coast. Next long ride I'll look for a downhill run to practice it. The most important thing of course would be NOT to advance the throttle at all, yikes that could be extremely ugly if the clutch engaged at 110km/h!

I put my ear way forward on the drive train and the engine itself is sublimely quiet, no valve noise at all ... which now has me worried that they don't have enough clearance :-(
You got it. Yep, wouldn't be a nice pic at all if one blipped the throttle when at speed in M while freewheeling. As for me doing this, I don't freewheel all the time as I do like the engine braking ability that the Burgy650's have. But the mountain routes are steep, and I can coast or freewheel down for quite some time, though I often stop at different points just to take in the views from time to time.

On a related note, I once came across a motorist in an AT (auto transmission) car on a motor in Auckland, NZ, who accidentally changed from D into R. The driver had been driving a MT (manual transmission) for most of the day prior and had a momentary lapse while driving the auto. Was not a pleasant situation. Big repair bill and likely lots of explaining to do.

As for the sound of mine, I think the noise is more a tranny noise than one from the engine, but the best way to know for sure would be to remove at a minimum the inspection cover, since many sounds are likely to be muffled and echo underneath all that tupperware.
 

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Discussion Starter #9
I don't give much thought to when I switch from D to M.. I get on the 4 lane.. get up to speed (usually around 75 indicated on the speedo), swiitch to M , and then put it in 6th gear. I keep it there and my speed varies between 68 to 94 indicated in 6th gear, but when approaching my exit, I switch to D mode for better engine braking and acceleration when I get off the exit.. I am always moving when switching between the two.. why do it any other way?
I get ya. I don't use the M mode all that much when riding most of the time, aside from a few real straight-a-ways, where I'm comfortable doing between 90-110km/h and will flick between D to M to take advantage of upping to the 6th overdrive gear sooner, and holding it there. Very similar to how you describe. On the odd occasion when I flick from D to M at lower speeds, I'm more mindful to watch the speed relative to the RPM so as not to drop the tranny into a too higher gear etc. It's useful to have some idea of the usual shift points for the M side of the CVT.
 
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