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Old 09-05-2009, 06:47 AM   #1
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R100GS Timing for a noob

I am still not terribly confident in my timing ability. I realize its a really pretty simple task, and that its actually kind of hard to bone up completely, but its seems to be equally weird to get just right... at least on my beast...

so here's my deal:

all things being equal I got the bean can on and everything is functioning.

I get a line and an OT mark, and a line and an S mark right next to one another. Some instructions tell me to align the S mark, or the S line with the center of hte timing hole.

Then rev it up to 3500 and should see a Z or an F. I got both, depending.

I usually use the left hand spark plug for the timing wire, but the image is actually slightly cleaner off of the right hand plug which I tried just for giggles. (I did my timing chain about 10 or 12 thousand miles ago and it was never really a rock solid image... it has always bounced around a bit and that has always bothered me.) Maybe my timing light is a cheap shit one.

Not really a problem, per se, but I cant quite make it top out at 3500. It usually more around 3k. who the hell knows how accurate the tach really is.

It is will top out that high, I feel like its either idling too high (should I just back the idle down at that point?) or if I set it so that S is in the field, it tops out slightly before 3k.

and feels like the idle is too low. should i just up it? also feels like its stumbling off idle. (I think I'm getting all the data correct here...)

Can one of you guys supply me with a brain-dead noob set of instructions for timing my bike? prty plz?

I can hook it all up and get in the neighborhood, but its the fine tuning thats getting me all geflustered.

thanks in advance.
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Old 09-05-2009, 07:16 AM   #2
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OT is TDC and used only for setting valves. "S" is static timing and should be aligned at idle. The advance timing, "ZorF" is more of a concern. Don't worry much about when the RPM's get you to see "Z" or "F", just that the mark is well aligned. Left or right cylinder does not matter, but a fluttery mark is usually a sign of timing chain slop. Too quick of an advance can be weak advance weight springs, but I would not sweat the 500 rpm's.
I have not done this, but you could possibly static time with an Ohmmeter or low voltage test light between the wires from the bean can. Rotate the engine and it should register when the hall sensor triggers. That moment should have the "S" in the window. If you can manually swing the weights, set engine to the advance mark and move the weights, you should see the meter trigger when right. Then run the engine and verify the advance timing. Again, the advance timing is more important than static so make it right.
If your marks are proper then adjust the idle speed and mixture after the bike is sufficiently warmed up. You should also check cable freeplay and synch carbs after tweaking.
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Old 09-05-2009, 07:32 AM   #3
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Mykill nailed it.

So are the S and Z marks aligned in the window?

And, by the way, idle speed has no effect on the advance unless it's really high - above 1500 rpm.

It's possible the advance springs are stretched and allowing the advance to occur too quickly, but I'd be more inclined to say the stumble off idle is more a tuning issue - mixture, balance, and maybe low idle. What is the idle speed?
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Old 09-05-2009, 07:51 AM   #4
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hey thanks guys- A little bit more info: I just got one of those ME ignitions to try out. Just installed on a working bike. I did the timing and carbs on the stock setup myself. I got my carbs as good as I though I could get them. It wasnt awesome, but I am trying to teach this to myself without the benefit of an experimental control to bounce results off of. (ie a known working bike) I just got it to where it didnt feel wrong.


Is it the S line or the S I shoud try to get in the center of the window? OK, thats not really that critical, but I'm looking for Z at the high end? somplace around 3-3.5K?

Moving the can around at idle timing slightly changes the idle. My idle before the swap was hanging right around 11-1300. Still is, sort of, because I got the can sort of in place, and adjusted so that it makes a compromise between idle speed and starting point and full advance point. I havent yet tried to adjust the carbs to work around the timing. Feel like I'm retarded right now. Timing feels less than spot on, as well.

I need to go mess around a little more and come up with some firmer data.
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Old 09-05-2009, 08:14 AM   #5
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Very often, cable synchronisation and off line stumble go hand in had. I found it to be a matter of less than a quarter turn of the throttle cable adjuster between a noticeable stmple and no stumble at all with everything else being adjusted nicely. Make sure your enricher (aka choke) is closing when it should be. Idle setting is an art but you don't need a degree to get it done. Read some of the earlier threads and use the different methods for idle adjustment described and see what works for you. I am a member of the "adjust by ear" and "maybe check with vacuum gauges afterwards" group. If the engine idles at around 1100rpm, no stumbles, no popping, just steady ... it is right. Off line performance then is only a matter of butterfly sync which comes down solely to cable sync. I do it at idle: with the bike idling open the throttle ever so slightly -> it should not appear to run on one cyclinder with the second one kicking in later. When I said "ever so slightly" I meant it: 1deg/sec twist ;-) or thereabouts. The cable sync at 3500rpm "until there is the least amount of vibration or similar vacuum pressure" turned out worse results than the method I use now! YMMV.

Ghost images (or what you describe as clean image) has to do with timing chain slop. When you replaced the chain did you also replace the two guides and spring as well as making sure that the piston underneath the spring is clean and moving nicely? Shouldn't concern you too much forthe time being: the tolerance of the 6deg S-mark reading I believe was +/-2deg that is 1/3 of the distance to TDC.

Your timing seems to be fine. Ride it.

EDIT after I saw your last post: set idle at S in center of window and then only observe if the Z/F mark appears in the center of the window. DON'T adjust idle setting to get the Z/F-mark centered, a couple of degrees don't matter much. The weights and/or the stop is the reason for it being in the top or bottom half of the window.
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Old 09-05-2009, 08:37 AM   #6
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Right, OK. What I heard from that is "Rideit, its close"


Yes, I did all the springs and guides when I did the chain. Everything but the sprockets themselves, (maybe I did a top one, I cant recall, now) and I thought I got it adjusted right... come to think of it I think I did a timing chain before the Anton rebuild, so I must have had it done professionally ( ) when it went back together.

I'm going to set everything back at starting specs and do it again. Do I need to do timing or carbs first?
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Old 09-05-2009, 08:50 AM   #7
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Timing and valve clearance first.
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Old 09-05-2009, 09:18 AM   #8
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Hi,
Quote:
Originally Posted by mykill
I have not done this, but you could possibly static time with an Ohmmeter or low voltage test light between the wires from the bean can. Rotate the engine and it should register when the hall sensor triggers. That moment should have the "S" in the window.
Just for the record, this technique is indeed mentioned in the BMW factory workshop manual for a static adjustment of the ignition. However, please do NEVER use a test light (that pen-style lamp with a wire and a needle tip) here - the semiconductor sensor would probably not survive it. Use preferably a simple device like this one from Rob Frankham.

Short explanation of the timing marks on a stock airhead:

- OT means Oberer Totpunkt = TDC and is usually not used for the ignition - exception see below.
- S means Spät = "late" ignition and is 6° before TDC. You should see this at idle (800...1100/min). Some (earlier) airheads have two more marks at +3° and -3° around the "S".
- Z means Zündung = ignition with full advance; this is 32° before TDC. You should see this above 3000/min. On earlier airheads (e.g. /7 era) this is labelled "F" for Frühzündung = "early ignition".

At idle, the "S" mark is visible in the center of the inspection hole. Below center = ignition (advance) too late; above center = too early. When you increase the rpm from idle, the "S" mark should thus disappear towards the top, and the "Z" mark should become visible from the bottom of the inspection hole around 3000/min.

If your strobe has an adjustable degree scale, you can turn that until you get the "OT" mark visible. The degrees that are set then tell you the advance of the timing at that rpm.

Usually, you adjust for correct Z or S with a strobe light, and then check both S and Z using a strobe light at the 2 rpm checkpoints given above. On the stock bike, you cannot adjust these independent from each other.
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Joerg screwed with this post 09-05-2009 at 09:41 AM
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Old 09-05-2009, 09:35 AM   #9
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oh and its almost hard to get the ZF to hang out in the window. Whats that about? I find it is I have to hunt around a lot to get it in the window, and its hard to find the right RPM where it stops.
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Old 09-05-2009, 09:49 AM   #10
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The line of the "S" is what to center up. There may be a slight mark on the engine case, like some one made it with a chisel, but it is real faint, that you can line the mark up on.

It may also depend on the timing light. Mine has a dwell setting. It won't show anything unless I set it at the 6deg. As I approach the 6deg setting on the light, you can see the marks start to jump around until then. It also has a tach function but doesn't work well on the GS as the GS fires on the off cylinder. I think in Snowbum's it says to set it slightly advanced to help with pinging.

Here is a manual you can down load to Adobe.

http://www.scribd.com/doc/414386/Bmw...al-r80Gs-r100R
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Old 09-05-2009, 10:36 AM   #11
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Quote:
Originally Posted by Stagehand
oh and its almost hard to get the ZF to hang out in the window. Whats that about? I find it is I have to hunt around a lot to get it in the window, and its hard to find the right RPM where it stops.
Wait ... at 3000 rpm it is normal (on my bikes )) that it "dances" a little bit around ... normal timing chain slack ... but if you open the gas (3500 or 4000/min) the timing mark should NOT move much further, especially NOT constantly off the top of the viewport - this would mean that ignition timing is way too early = Danger. Could be worn-out advance springs or whatever.

If your strobe light has a manual advance dial, make sure it is set to Zero ...

The ignition of the bike is absolutely stock? No dual-plugging?
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Old 09-05-2009, 08:13 PM   #12
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tune the valves cold
set the carbs to basic starting settings

start the bike, let it settle for a minute and adjust the carbs to get a decent idle speed.

use the timing light on either plug wire and rotate the beancan until the line under the S lines up with the notch in the viewing hole. If it's jumpy a little, just interpolate on the fly and stick it in the middle of the blur.

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If your idle rises or drops, don't touch the beancan. adjust at the carbs.

once this is done, as long as you can twist the throttle and watch the S drop down (or maybe go up, can't remember) and the Z eventually shows up, you're happy.

Ride till it's warm, tune carbs. drink beer (1 for the kid too!) and be happy.




finally, give a detailed report of how the ME ignition advance holds up under your "special" treatment.
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Old 09-08-2009, 06:10 PM   #13
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Quote:
Originally Posted by Joerg
Wait ... at 3000 rpm it is normal (on my bikes )) that it "dances" a little bit around ... normal timing chain slack ... but if you open the gas (3500 or 4000/min) the timing mark should NOT move much further, especially NOT constantly off the top of the viewport - this would mean that ignition timing is way too early = Danger. Could be worn-out advance springs or whatever.

If your strobe light has a manual advance dial, make sure it is set to Zero ...

The ignition of the bike is absolutely stock? No dual-plugging?
Hi Joerg- bike is stock except for the newly installed ME ignition.

Cheap strobe with no manual anything 'cept a trigger.

Tested again tonight.

Went down there and when cold, man it was dead nuts solid. Brought a little tear to my eye how solid the S mark was.

Well, ok I sets it so the line under the S is just at the center notch in the case and check for 3K rpms.

The Z mark comes and goes, and just goes up out of view a little. I havent been able to get it to NOT go out of view, and the best I can do is get it so the tang of metal the Z is imprinted on does not go out of view at all past 3.5K ie it stops moving and statically the S is quite close to where it should be.

Took it for a ride and realize that idle wants to jump out from under me because its at about 1500. I back it down at the throttle screws to 11 or so.

seems to work ok. Midrange there is an obvious improvement, unbeknownst to me because of my paranoia.

after I got back from the ride I shot the timing again and the S is jumping all over hell. Chain must heat up.

Same deal. Z just barely out of view. No real pinging that I can tell, meaning its nowhere near what it sounds like when the R60 pings.


SO- Am I in DAnger DAnger?


Thanks for bearing with me, guys! and for the help!
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Old 09-08-2009, 06:30 PM   #14
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S dead on when cold, jumping all over the place warm? SHOULDN'T! (no, Jason, your chain doesn't heat up THAT much!)

ME ignition?

Your Z (=max advance) is fine. No danger, I would think.

But your S-mark concerns me!
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Old 09-08-2009, 06:45 PM   #15
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its maybe a millimeter or two I guess... not a solid image.

Something is heating up and getting sloppy. Me?

ME = Motorrad Electric. I think digital advance is the big diff, besides a really butch billet hallsensor.
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