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Detonation ??


kiwiaudio

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After replacing the hall sensors (thanks Mick) I static timed and bolted her up. Under moderate to heavy acceleration when up to temperature, I have this rattling noise in 1,2 & 3rd gears that appears to be coming from the engines front. It is not bad when the bike is cold, and I'm suspecting detonation, or "pinging". It is always very hard to detect in 4th and 5th gears.

I'm going to try a gallon of high octane to see if the noise is lessened, and if it is, then it has to be detonation, right ?

So - gearbox rattle or detonation ???

I'd like to check the timing with a light but my manuals give no assistance with setting the timing this way, although I seem to recall seeing something in these pages that is relative. I'm unsure at what rpm the "S" and "Z" are supposed to appear in the center of the window - anyone know this?

Another idea - do you think richening the mix with adjusting my techlusions acceleration pot might help?

 

After fighting my demons with this bike, I finally feel that I could live with it if I could solve this noise.

 

Any help would be appreciated.

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After replacing the hall sensors (thanks Mick) I static timed and bolted her up. Under moderate to heavy acceleration when up to temperature, I have this rattling noise in 1,2 & 3rd gears that appears to be coming from the engines front. It is not bad when the bike is cold, and I'm suspecting detonation, or "pinging". It is always very hard to detect in 4th and 5th gears.

I'm going to try a gallon of high octane to see if the noise is lessened, and if it is, then it has to be detonation, right ?

So - gearbox rattle or detonation ???

I'd like to check the timing with a light but my manuals give no assistance with setting the timing this way, although I seem to recall seeing something in these pages that is relative. I'm unsure at what rpm the "S" and "Z" are supposed to appear in the center of the window - anyone know this?

Another idea - do you think richening the mix with adjusting my techlusions acceleration pot might help?

 

After fighting my demons with this bike, I finally feel that I could live with it if I could solve this noise.

 

Any help would be appreciated.

 

Mark, that does sound like an early spark (detonation) but could also be a flopping alternator belt, or other mechanical sound, or even trans noise.. By all means try some premium fuel (run your tank low first)..

 

On your timing question-- the OT is top dead center,, The S is about 5-6° btdc (base ign timing under about 1000 rpms, the Z is max advance (I don’t know how many ° that actually is though or when it is all in by.. Just rev it (the engine) until the timing quits advancing in the timing hole & that should be the Z mark..

 

If you don’t mind running premium fuel you can probably run it a couple of degrees advanced as that will give you little better idle & probably a little crisper off idle..

 

Twisty

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I have not tried premium gas yet, but thought I'd revisit the timing issue first.

OK - Static timing is right on. (digital voltmeter on the orange wire from the HES, turn engine anticlockwise until I lost 12V - "OT" is smack in the middle of the window.)

"S" (6deg) is right in the middle of the window @ 1000 rpm.

"Z" comes up around 4000 rpm, but it then surpasses the Z as I rev further. This is probably all as it should be frown.gif

 

No one seems to be able to tell me just how many degrees of advance "Z" actually is, not that it is adjustable independantly, but I'm thinking that if I could move the HES plate to properly align the "Z" at the specified RPM - then perhaps the pinging would cease! Of course, "S" (6deg @ idle) hopefully won't move much!

I have my dealer looking into this at this very moment, and as usual my questions have never been asked before. He won't call back and I'll be called a fastidious nutcase once again. Ha Ha ! (welcome to my world!)

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I have not tried premium gas yet, but thought I'd revisit the timing issue first.

OK - Static timing is right on. (digital voltmeter on the orange wire from the HES, turn engine anticlockwise until I lost 12V - "OT" is smack in the middle of the window.)

"S" (6deg) is right in the middle of the window @ 1000 rpm.

"Z" comes up around 4000 rpm, but it then surpasses the Z as I rev further. This is probably all as it should be frown.gif

 

No one seems to be able to tell me just how many degrees of advance "Z" actually is, not that it is adjustable independantly, but I'm thinking that if I could move the HES plate to properly align the "Z" at the specified RPM - then perhaps the pinging would cease! Of course, "S" (6deg @ idle) hopefully won't move much!

I have my dealer looking into this at this very moment, and as usual my questions have never been asked before. He won't call back and I'll be called a fastidious nutcase once again. Ha Ha ! (welcome to my world!)

 

Mark, another way to check the base timing is to turn the crankshaft (either using the front pulley center bolt or placing in high gear & using the rear wheel) backwards until the TDC mark is just below the timing hole.. Then turn the ign switch ON & let the fuel pump run, then time out.. Now with the ign switch still ON slowly rotate the flywheel in the running direction until the fuel pump again comes on.. That means the HES has just triggered the ignition cycle,, that should trigger at TDC.. (real easy way to check base timing)

 

Twisty

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Mark, another way to check the base timing is to turn the crankshaft (either using the front pulley center bolt or placing in high gear & using the rear wheel) backwards until the TDC mark is just below the timing hole.. Then turn the ign switch ON & let the fuel pump run, then time out.. Now with the ign switch still ON slowly rotate the flywheel in the running direction until the fuel pump again comes on.. That means the HES has just triggered the ignition cycle,, that should trigger at TDC.. (real easy way to check base timing)

 

Twisty

 

I tried that with my bike a few weeks ago, but it doesn't work. When turning the engine clockwise, mine only cycles the pump when the timing marks are on the opposite side of the sight window. If I turn the engine counter clockwise, then it will cycle the pump at the "correct" place like you explain. I scratched my head about it a few times, then just kind of shrugged my shoulders and put it all back together. The bike is running great, so I'm just assuming it is set correctly.

 

In the mean time, I have built on of the electronic boxes to properly set the timing with the HES. One of these days I'll get around to checking it.

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I have not tried premium gas yet, but thought I'd revisit the timing issue first.

OK - Static timing is right on. (digital voltmeter on the orange wire from the HES, turn engine anticlockwise until I lost 12V - "OT" is smack in the middle of the window.)

"S" (6deg) is right in the middle of the window @ 1000 rpm.

"Z" comes up around 4000 rpm, but it then surpasses the Z as I rev further. This is probably all as it should be frown.gif

 

No one seems to be able to tell me just how many degrees of advance "Z" actually is, not that it is adjustable independantly, but I'm thinking that if I could move the HES plate to properly align the "Z" at the specified RPM - then perhaps the pinging would cease! Of course, "S" (6deg @ idle) hopefully won't move much!

I have my dealer looking into this at this very moment, and as usual my questions have never been asked before. He won't call back and I'll be called a fastidious nutcase once again. Ha Ha ! (welcome to my world!)

 

Mark,

Only way to get it closer to TDC is to lock the flywheel and set the HES by rotating it at TDC.

You will NOT be able to change the total advance (Z) without changing the initial 6 degrees (S) that the Motronic dials in. frown.gif

Adding a little more fuel might help BUT, detonation usually occurs in higher gears with high engine load. If you ONLY hear it in the lower gears under moderate throttle, I'm betting it is something else.

 

Mick

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I tried that with my bike a few weeks ago, but it doesn't work. When turning the engine clockwise, mine only cycles the pump when the timing marks are on the opposite side of the sight window. If I turn the engine counter clockwise, then it will cycle the pump at the "correct" place like you explain.
I remember Mitch noting that in a thread a while back about setting timing. Apparently it is necessary to move the trigger plate backwards past the sensor to get it to trigger under static conditions.

 

Related question for Mick or Twisty... back when I purchased my bike I noticed that the 'S' mark was aligned in the center of the window (at idle) when using a timing light, which makes sense and apparently reflects a proper timing setting (or at least that's how it came from the factory.) Why not simply set timing on these bikes with a timing light, as is done with automobiles?

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I remember Mitch noting that in a thread a while back about setting timing. Apparently it is necessary to move the trigger plate backwards past the sensor to get it to trigger under static conditions.

 

Thanks. Thats what I assumed after playing with it for a little while. Using that theory, my bike is running 2-3 degrees of advanced timing. One of these days I would like to dial it back a little and see if it helps my occational pinging issue, but for the time being........it will just have to do.

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Related question for Mick or Twisty... back when I purchased my bike I noticed that the 'S' mark was aligned in the center of the window (at idle) when using a timing light, which makes sense and apparently reflects a proper timing setting (or at least that's how it came from the factory.) Why not simply set timing on these bikes with a timing light, as is done with automobiles?

 

Seth,

You 'can' but there is always some error trying to see that mark on the oilheads. I also believe the different CCPs vary the timing too so the S mark isn't always centered.

I think the static TDC method is the easiest......lock the flywheel with the dowl pin, hook up either your test box or a good digital meter OR a 12V LED and set it.

 

Mick

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Guys, it is not detonation. I tried Premium fuel and it made no difference. I was grabbing a straw with that one anyway - it just sounded too loud to be detonation.

 

Sounds like a coffee can half full of stones being shook up any time I accelerate. Noise is coming at me through the steering head opening, and it definitely gets worse as the engine heats up.

If I ever get around to installing a radio, I don't think it could ever compete with this racket anyway !

I've rechecked the alternator, belt etc. and all seems OK.

Other than engine internals, I don't know what it could be, and what inside could do this?

 

I've installed the modified cam chain tensioner, which worked great, but it was not the reason for this particular noise.

 

Yesterday, while waiting for a buddy at an ATM, i stuck my ear down by the key and blipped the throttle at idle a few times. Sounded for all the world like piston knock !

The engine was as hot as I've ever had it (6 bars on RID).

I wonder if the top end is all coked up with carbon??

 

Hmmmm !?

 

I sure wish one of you experienced guys lived close to me, so I could have you ride this thing !

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Kiwi, as a rule piston rattle is more of a cold engine thing that gets better as the engine heats up (there are exceptions to about any general rule though).. Piston pin rattle is a possible acceleration type rattle but that is usually more of a tapping & not a can full of rocks noise..

 

I suppose it’s possible you could have some type of timing chain noise (those can rattle like loose bolts in a can).. Could also easily be a transmission bearing or loose shaft noise or something in the clutch drive assembly..

 

Still might also be a detonation or preignition problem that premium fuel didn’t remove.. Could happen if you have excessive carbon build up..

 

I would suggest a good HOT engine compression test & if your compression is around normal then don’t worry about carbon.. If the compression is high then look for a carbon problem..

 

Next I would visit your local discount auto parts store & by an inexpensive mechanics stethoscope.. Pull the stinger off the end of the hose (you want an open hose).. Then add about 3’-4’ of hose to the existing hose.. Tape the open end of the hose to different places on the motorcycle frame, under the fuel tank, around the trans area, etc.. Then place the ear pieces in your ears (you will need a shorty helmet for this) then ride the motorcycle.. It shouldn’t take long to hone in on the area that the noise is loudest or most direct.. Make sure the open end of the hose isn’t pointing into the air stream or you will get lots of hissing & wind rush noise in the ear pieces.. Hopefully this will at least get you close to the area that the noise is coming form..

 

You might also want to pull the oil filter off & cut it open (don’t use a hack saw or you will get lots of metal shavings from that).. Then open up the internal pleated filter element & look for signs of metal or other internal engine particles.. (clean filter is real good news)..

 

I presume you checked the alternator for ALL it’s attachments being tight (those things will vibrate like crazy if any attachments are loose)..

 

Look for the center stand to be vibrating on the Catalytic Converter (will happen if the rubber bumper comes loose or the bumper tang bends)..

 

Maybe pull the valve covers & rotate the engine to see if you have any loose valve adjusters (lots of valve lash).. There has been occasions where the end of a push rod will come loose & cause valve lash problems.. (usually not a can of rocks noise though)..

 

I guess as a last resort pull the front alternator belt cover, then MARK the position of the HES sensor (so you can put it back) then loosen the 3 retaining bolts & rotate the plate clock wise as far as it will go (that will retard the ign timing a few degrees).. If that effects the noise then you know it is spark timing related..

 

This is difficult as engine noises are difficult enough to diagnose when the vehicle is right in front of you & next to impossible to diagnose over the internet..

 

Twisty

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Bill, you have some great ideas there - especially the hose tester. I'll get right on that one.

And yes, I definitely need to have another good look at the alternator mounts - this seems more likely than anything else as the location is right.

I'll report back on what I find - if anything?

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Hey Mark, just wondering... did you notice the noise after you replaced the clutch & transmission, or was it OK until the Hall sensor replacement?

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Hey Seth,

Actually, the noise has always been there, it was just down the list somewhat - you know ! (Long list when I think about it)

It is now however, my number one P.I.T.A item, and if I could solve it, I think I could learn to like the old girl !!

I've had this thing two months now and it has been apart about half that time, but i am still intrigued !

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I tore her apart again and found several items contributing to my noise problem. Or so I thought !!

 

The previous owner had neglected to refit the three nuts that surround the headlight holding the front fairing on. That removed some vibration noise.

 

The center stand was indeed rubbing on the cat. convertor -Thanks Bill !

I installed a longer rubber bumper pin, and again this removed some vibration noise.

 

The front fender had been replaced at one time with one from an 1150, and it was rubbing on the fork tubes. A little automotive door edge trim fixed that, but i don't think it was making any noise anyway.

 

The Rider information display had broken one of the plastic screw mounts away and the screw was missing, creating a rattle in the dash. Epoxied that and screwed tight.

 

I then took her for a ride with the minimum amount of tupperware installed that I could get away with. It seems that every extraneous noise has gone away, except the one I was mainly concerned with, which of course is now even more prevalent !

 

Hooked up Bills idea of a stethoscope and hoses, and took off again. After moving hoses around, I have arrived at the transmission, which makes a lot of noise as everyone says they do, but is much worse at the related time and gear selection. Specifically 2nd and 3rd @ 3-4000 rpm.

 

I know for a fact that this noise was there when I bought the bike, but it was clouded by so many other things, some real - some imagined. (The mind is a wondrous thing when diagnosing an annoying noise!)

 

I looked hard at the trans when I had it apart to do the Seth wave washer replacement, and could see nothing unusual other than the bearing issue that has been beaten to death in the "chocolate oil" thread. My bearing was not one of the really bad ones, and there was not much in the way of metal filings in the original chocolate oil which had been in the trans for about 5000 miles according to the previous owners records.

Although ......., a few days after assembly it did demonstrate the neutral gear rattle that I hadnt noticed before. (goes away with clutch pulled in). I did not give that much cause for concern as everyone seems to have this problem it seems, and it is apparently exacerbated after removing the wave washer - mine IS loud though ??

 

So....... maybe I just have a bad case of gear whine, or I screwed something up when I did the tranny job, but as stated, it had this noise when I bought it.

 

I've about had it with this, but I'm going to change the tranny oil again. If its clean, I'm going to try and forget this.

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I tore her apart again and found several items contributing to my noise problem. Or so I thought !!

 

The previous owner had neglected to refit the three nuts that surround the headlight holding the front fairing on. That removed some vibration noise.

 

The center stand was indeed rubbing on the cat. convertor -Thanks Bill !

I installed a longer rubber bumper pin, and again this removed some vibration noise.

 

The front fender had been replaced at one time with one from an 1150, and it was rubbing on the fork tubes. A little automotive door edge trim fixed that, but i don't think it was making any noise anyway.

 

The Rider information display had broken one of the plastic screw mounts away and the screw was missing, creating a rattle in the dash. Epoxied that and screwed tight.

 

I then took her for a ride with the minimum amount of tupperware installed that I could get away with. It seems that every extraneous noise has gone away, except the one I was mainly concerned with, which of course is now even more prevalent !

 

Hooked up Bills idea of a stethoscope and hoses, and took off again. After moving hoses around, I have arrived at the transmission, which makes a lot of noise as everyone says they do, but is much worse at the related time and gear selection. Specifically 2nd and 3rd @ 3-4000 rpm.

 

I know for a fact that this noise was there when I bought the bike, but it was clouded by so many other things, some real - some imagined. (The mind is a wondrous thing when diagnosing an annoying noise!)

 

I looked hard at the trans when I had it apart to do the Seth wave washer replacement, and could see nothing unusual other than the bearing issue that has been beaten to death in the "chocolate oil" thread. My bearing was not one of the really bad ones, and there was not much in the way of metal filings in the original chocolate oil which had been in the trans for about 5000 miles according to the previous owners records.

Although ......., a few days after assembly it did demonstrate the neutral gear rattle that I hadnt noticed before. (goes away with clutch pulled in). I did not give that much cause for concern as everyone seems to have this problem it seems, and it is apparently exacerbated after removing the wave washer - mine IS loud though ??

 

So....... maybe I just have a bad case of gear whine, or I screwed something up when I did the tranny job, but as stated, it had this noise when I bought it.

 

I've about had it with this, but I'm going to change the tranny oil again. If its clean, I'm going to try and forget this.

 

Kiwi, trans/clutch noises are a real problem on the BMW oil head twin.. First you have the very thin aluminum trans & clutch housing castings (they allow ALL internal noises to pass right through),, then you have the non spring dampened clutch drive disk (put one of those in a car & see what kind of noises it will generate),, then you lots of slop between the gear drive dogs (no syncros or multiple tight gear engagement slider rings, just very loose fitting dogs),, then you have a trans full of straight cut gear teeth,, then to make it worse you couple that to a large piston harsh firing 2 cylinder engine with no rubber mounting isolation & a dry single plate clutch.. Heck my old tractor has more engine/trans isolation that your high dollar BMW does..

 

Twisty

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Kiwi, trans/clutch noises are a real problem on the BMW oil head twin.. First you have the very thin aluminum trans & clutch housing castings (they allow ALL internal noises to pass right through),, then you have the non spring dampened clutch drive disk (put one of those in a car & see what kind of noises it will generate),, then you lots of slop between the gear drive dogs (no syncros or multiple tight gear engagement slider rings, just very loose fitting dogs),, then to make it worse you couple that to a large piston harsh firing 2 cylinder engine with no rubber mounting isolation & a dry single plate clutch.. Heck my old tractor has more engine/trans isolation that your high dollar BMW does..
Yeah, it's amazing that they are even as quiet as they are. The shifting mechanism in particular doesn't exactly strike me as a precision device.

 

I would guess that the extra noise in neutral is related to removal of the wave washer. Certainly worth it if this provides the necessary fix but only time will tell on that. In the meantime I'd say ride the bike... if there was anything seriously wrong in the transmission you probably would have detected it when you had it apart.

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Guys, The oil looked like the day I put it in.

1 more bottle of Mobil 75/140 and another $16 later, I am moving on.

 

Thanks Bill & Seth for at least easing my mind about this.

I have to believe though that 70K ago this transmission did not sound like this, or they surely would never have sold a one !

 

One would think that a marquee that is in the upper echelon of quality automotive brands would have laughed Getrag out the door with this crash box they call a transmission !

 

Oh well, I do have to keep reminding myself that I do only have around $6K invested in this bike. I'm going to put a stereo on her anyway and try to drown out the noise. Though earplugs would be a lot cheaper .. yes ?

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One would think that a marquee that is in the upper echelon of quality automotive brands would have laughed Getrag out the door with this crash box they call a transmission !

 

Oh well, I do have to keep reminding myself that I do only have around $6K invested in this bike. I'm going to put a stereo on her anyway and try to drown out the noise. Though earplugs would be a lot cheaper .. yes ?

 

Mark,

Read this article: http://www.largiader.com/tech/oiltrans/interview.html

 

It was actually BMW who screwed-up the transmissions. smile.gif

 

MIck

Tucson

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I have worked with auto suppliers for many years & their first response is usually to blame the original parts requester, or supplied designs, or end user.. While there is probably little doubt BMW didn’t get their act together on the original design I doubt Getrag is blameless here either.. My guess would be an interview with BMW chief engineering would yield just the opposite as far as blame goes..

 

 

If you are having a house built & the design is flawed would you expect the builder to just build it anyway (even knowing there is a flaw in design) or would you expect him to work with you to get it right? Then if you insisted on it being built to a flawed design at least get you to sign a wavier to take him out of the blame loop..

 

There are ALWAYS 2 sides to any story & usually the truth lies somewhere in between the 2 sides..

 

Twisty

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Great article Mick. Dated sure ... but still good stuff. The talk is about the M94 O ring transmission predominantly, but one line ....

 

"And we can tell you this: total BMW shifting pleasure is coming - and soon. "

 

is comical, unless "soon" is considered undefinable. This pleasurably shifting box is not my M97 !!!

Maybe the 1200's are better ?

Some ten years later may be "soon"!

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Great article Mick. Dated sure ... but still good stuff. The talk is about the M94 O ring transmission predominantly, but one line ....

 

"And we can tell you this: total BMW shifting pleasure is coming - and soon. "

 

is comical, unless "soon" is considered undefinable. This pleasurably shifting box is not my M97 !!!

Maybe the 1200's are better ?

Some ten years later may be "soon"!

 

Mark, actually the 1200 is much better & with helical cut gears a bit quieter also.. BUT, I haven’t ridden a 1200 high miler so maybe they get just as bad at high miles as the 94 & 97..

 

Twisty

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