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Old 10-21-2013, 08:19 PM   #1
akpasta OP
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BMW R100/7 Timing Queastion

Good Evening,

I've had my R100 for about four months now and already I've taken it on some great adventures, I love it. In the time I've had it I've performed most of the basic tune-up procedures, including a new set of points. My shop manual has been an invaluable tool.

Knowing full well that a new set of points wears in and needs adjustment pretty quickly (in my case probably a bit too long) I pulled the points cover off and set about re-setting the gap, which had closed considerably since I first set it when installing the new points.

My question is, when you set the gap again, do you need to change the ignition timing using a static or strobe light and the window on the engine case? It seems to me that if you set the gap the same, which I did, using that nifty tool someone sold me via this message board, the timing will be the same too. Correct?

My next trip, slated for late November will be to the grand canyon (weather permitting), looking forward to that! Never been!

Thanks!
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Old 10-21-2013, 11:18 PM   #2
supershaft
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Quote:
Originally Posted by akpasta View Post
Good Evening,

I've had my R100 for about four months now and already I've taken it on some great adventures, I love it. In the time I've had it I've performed most of the basic tune-up procedures, including a new set of points. My shop manual has been an invaluable tool.

Knowing full well that a new set of points wears in and needs adjustment pretty quickly (in my case probably a bit too long) I pulled the points cover off and set about re-setting the gap, which had closed considerably since I first set it when installing the new points.

My question is, when you set the gap again, do you need to change the ignition timing using a static or strobe light and the window on the engine case? It seems to me that if you set the gap the same, which I did, using that nifty tool someone sold me via this message board, the timing will be the same too. Correct?

My next trip, slated for late November will be to the grand canyon (weather permitting), looking forward to that! Never been!

Thanks!
In theory it should be but there are reasons why you want to set the timing dynamically with a timing light. Any form of static setting isn't as accurate. Besides, there is no reason to sweat the gap on our bikes other than the gap being too narrow. Too wide, IF you have room, doesn't hurt a thing performance wise.
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Old 10-21-2013, 11:24 PM   #3
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Originally Posted by akpasta View Post
Good Evening,

I've had my R100 for about four months now and already I've taken it on some great adventures, I love it. In the time I've had it I've performed most of the basic tune-up procedures, including a new set of points. My shop manual has been an invaluable tool.

Knowing full well that a new set of points wears in and needs adjustment pretty quickly (in my case probably a bit too long) I pulled the points cover off and set about re-setting the gap, which had closed considerably since I first set it when installing the new points.

My question is, when you set the gap again, do you need to change the ignition timing using a static or strobe light and the window on the engine case? It seems to me that if you set the gap the same, which I did, using that nifty tool someone sold me via this message board, the timing will be the same too. Correct?

My next trip, slated for late November will be to the grand canyon (weather permitting), looking forward to that! Never been!

Thanks!

Why make assumptions? Always check the timing when you button it up. Takes a minute. If it needs correction do that. If not, not. you can also point your strobe light at the points to observe advance operation, depending on the model.


Crossing the Sierras and the high plateau in November? Better be an RT with some heated gear. You is gonna freeze your cajones...and plan time to lay up while fresh snow melts off the high passes...

That country is nice in the off season---deserted. But it's best in the spring when the desert is in bloom and before the heat and tourists of summer have built. Can still be a very cold trip.
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Old 10-21-2013, 11:29 PM   #4
akpasta OP
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When I first installed the points I set the timing static for "F" and then checked advance timing with a strobe because I've been taught advance timing is the thing that matters most. Getting great performance from that. Just wanted to re set the gap wondering if that's enough. So I guess it is?
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Old 10-21-2013, 11:37 PM   #5
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Thanks Plaka for your advice. You're right, it was just getting dark and I was cutting corners.

I admit the Grand Canyon is maybe a bit ambitious for November. Plan b is Mono Lake if there's not enough time
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Old 10-22-2013, 12:22 AM   #6
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Hey Plaka, When I say that advance timing is "what matters most" I mean that I've been told if you don't at least check to make sure your advance timing isn't over-advanced, you can fry an engine. What I was taught was still to set it static with your static light bulb, then start the engine up and check the markings with your strobe to make sure you don't over-advance at full advance, basically you're just checking the advance unit to make sure it's doing what it's supposed to.

I agree that even if you think you can observe the exact rpm when your advance unit is finally fully-avanced it's "loose"... to say the least. Brings up a question. I've met a couple people who use a paper-clip or something to pull the advance unit to fully advanced with the engine off of course, and then static time it that way..... that's the kind of thinking you're trying to dispel, correct? Someone showed me this method once on a 2stroke Yamaha, never tried it myself, but the advance unit on the Yamaha was basically the same as our BMWs.

I did notice something interesting when I re-set the point gap. I remember when I replaced the points, set the gap, and set the idle timing with my static light that it was idling around 1000-1100, but after the point gap closed after the last couple thousand miles it would idle at 800-1000 (which I prefer), then today after just re-setting the gap to spec, it was back at 1000-1100. What could be causing that, is it the idle tuning on my carb?
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Old 10-22-2013, 12:27 AM   #7
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Keep it simple. If the bike runs fine and there are no issues leave it alone.
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Old 10-22-2013, 01:37 AM   #8
Plaka
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Originally Posted by akpasta View Post
Thanks Plaka for your advice. You're right, it was just getting dark and I was cutting corners.

I admit the Grand Canyon is maybe a bit ambitious for November. Plan b is Mono Lake if there's not enough time
I'd skip Mono lake too. I've been there for a couple of days with sea kayaks and there is a lot to see. much history both old and new---the cinder cone in the middle of the lake is something---it's also fake, as you realize when you get close in a boat. It's an old movie set. One of the islands in the lake is entirely massive chunks (house sized) of black volcanic glass. Challenging hiking. . Also a lot of ancient history. I'm not sure you'll see the bands of brine flies in the winter. They were once an important native food source and trade item, etc.

BUT, to get there you have to cross a national park, so you need a parks pass. Buying a one shot costs almost as much as a year pass. But it you got a year pass for next year you could use it at Mono and Grand Canyon---canyonlands in general.

You also have to cross the Sierras. Think wet road from snowmelt on a nice day---but black ice in a curve that is shaded---not this kid. Bay area will fool ya---it snows in the rest of the world

I'd run 101N to Mendocino. Real nice up there, I mean REALLY nice. You can score off season rates at the B&Bs if you camp that way. Also you have the 101 run to see how you get along with riding in those temps. Plenty of places to bail (or at least warm up) before you get onto the backroads and up into the remote stuff. Mendo is way back in and the folks who live there year round like that.

I got good and hypothermic once running 1 N to oakland out of LA. on an open bike. Got dark and into the 40's and I didn't have the uber cold weather gear. Fall season and it came on slowly enough that I didn't realize how much of a haze I was riding around in. Made a left directly in front of an oncoming truck after dark. The driver was way on the ball or I would have been very killed very quickly. Got my attention to say the least and I did some serious apologizing to the guy, thanked him profusely and got off the road. Anyway the Mendo run keeps you at low elevation and near the coast, more moderate temps.
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Old 10-22-2013, 09:17 AM   #9
disston
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The total amount of timing the ignition reaches at full advance is important and more important because of the danger of destroying an engine with too much advance. This is how it works when things are working properly and this is how it works when things are slightly worn or a little out of tune. If things are severely worn or very out of tune it is another ball game.

A few extra degrees of advance may not hurt much but the longer an engine is left to run with too much advance or the more the engine is advanced too far then the greater and the sooner destruction may occur.

Static timing is set at the S mark with the engine not running. It is used to install new points and adjust used points. If you are familiar with the workings of the advance unit you have and therefor know at which mark the static timing will produce the correct amount of advance at full advance then you may stop there. It is recommended to check the full advance with a timing light tho to be sure the rest of the system is performing correctly. At home when I install new points I check full advance with a timing light. If on the road I'm not likely to have the light with me and I would use static only.

Th ignition points wear in several ways both generally produce a lessening of dwell angle or closing of the point gap and consequently a retarding of the advance. This can be noticed by a reduction of performance, less gas mileage and sometimes over heating of the unit.

The principle of , "Points dwell effects timing, but ignition timing does not affect dwell." can be used to your advantage. It is difficult to regap ignition points and get them to exactly the same dwell you had before when they were new. Go ahead and try to set the gap with a feeler gauge used just on the edge of the contacts. It is generally accepted that the problem is the gap has closed, so open them up. I often do this by eye sight alone. Then with out moving the plate or changing timing check the timing. You are right, the timing has changed because the gap has closed and the gap or dwell was changed which is the only reason the timing is off. If the timing is now too advanced the gap was opened too much. If the timing is still too retarded they need to be opened a little more.

The whole problem can usually be handled this way but sometimes a finer adjustment is needed. The advance unit on the end of the cam shaft is located by a D shape. Because of the miles these parts are worn and the advance unit can usually be rotated a small amount even when in place if the nut is loosened. Careful to not over tighten the nut. It's a very common part broken because it is very easy to break the stud off the end of the cam shaft. Rotating the advance unit changes timing a little and most machines work with the unit set towards one direction or the other. If it is already at the end of rotation in the direct you need then you may have to actually move the points plate or try some more gap on the points. If you are removing the advance unit to set the gap then the timing will likely not be same when you put the unit back together because of this. It is confusing in operation as much as it is in explaining it. But there are a lot of factors affecting the operation of ignition points. You have to keep in mind all of this, the gap, the rotation of the advance unit and the points plate.

There is a lot of leeway available for the set up of ignition but the amount of advance should be kept as close as possible to stock for single plug bikes. New points will wear in the most and sometimes need adjustment after only a couple hundred miles but after this the time intervals between adjustments should be much longer.
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Old 10-22-2013, 09:28 AM   #10
therealbatman
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Originally Posted by akpasta View Post

I admit the Grand Canyon is maybe a bit ambitious for November. Plan b is Mono Lake if there's not enough time
That's putting it mildly...The last trip I made to the GC was in Mid September 2003 and it was 28 degrees in the evening and lots of large animals wandering around.

Keep warm
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Old 10-22-2013, 09:59 PM   #11
akpasta OP
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Disston, Plaka, et al, great advice, good stories. Maybe I'll try to talk my buddy into a different trip.

As for timing, one thing I notice is that in order to get the static light to come on near the S-mark I have to move my points plate clockwise all the way (retard) until the plate won't move anymore and still it's not quite there, it's still a bit advanced. However when I check the full advance with the engine running and a strobe at 2600rpms the "F" is clearly in the window so it appears the full-advance is not over-advanced. But something seems not right here. At first I assumed it was due to the new points and that they need to wear in, but after a few thousand miles I'm not so sure anymore.

Should I turn the point plate to the middle of it's adjustment direction and re-set the gap? Can things get sort of thrown out of whack if you adjust the points first with the plate adjusted to an extreme either way? Could it be that my advance unit is shot?

By the way it still idles and runs great and I've put a few thousand miles on it this way... wondering...
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Old 10-22-2013, 10:35 PM   #12
disston
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The static or idle advance is where the advance unit starts. It will advance a certain amount till we reach total advance or full advance at 3000 rpm or so. If the static timing is set for 6* and full advance is set at 34* then the advance unit moved the timing 28*. If you set static aT 10* full advance would be 38*. If you set the static timing at zero then full advance would be 28*. The advance unit always advances the ignition the same amount.

The machine was built with an advance unit that moved the correct amount so that timing would be at S at idle and at F at higher rpm. These advance units were often customized. It sounds like you have one with a restricted amount of movement and weak springs. 2600 may not be too soon and less movement may work OK for you. By having the advance start higher and reach full advance sooner the bike may be faster. This is the theory that was employed to try and coerce more performance from the Airheads.

Look at the tiny holes in the top of the advance unit where the pins stick up and the springs are attached. Does it look like the holes have been modified with brazing to make the hole smaller. A smaller hole will allow less movement of the pin and less total advance from the modified unit. This is how it was usually done. The pins can also sometimes be bent.

The springs of your advance unit may be worn out. If they are they don't return to zero and they are weak and advance faster. New springs may fix the problem.

The Airheads with this type of advance unit used 4 different units supplied by Bosch. We tell them apart by the last three digits. Early bikes, mostly found on /5's, end with 005 and 007. These advance units take spring part #12 11 1 356 546. The later bikes with Bosch units ending with 010 or 012 take part #12 11 1 357 627. The springs are sold each and so you need to ask for two. BTW, this is probably the most expensive part per pound on your bike. The tiny springs are not cheap.

When you put the new springs on take the advance unit off the bike and perform the operation on a clean work bench or the kitchen table where you will be able to find the small stuff you drop. Take it apart and clean it. Polish any ruff edges with fine sand paper. Polish the parts that rub together and make it all work smoothly. Put together with a light grease. Be careful to not loose any of the small parts or the tiny fiber washers. None of the parts, except the springs, are available separately. Clean the inside of the bore that rides on the end of the cam shaft. This part rotates in operation. Should be clean and lightly greased.

When finished it should be smooth and well oiled but not dripping in oil or grease. This can be thrown off by the centrifugal force and contaminate the points.

After this the unit will behave more as it was designed to however they don't always have the exact amount of advance as original. Wear and tear. The full advance mark is the more important but you will probably get closer to the idle mark too. Don't forget you can advance or retard a small amount of timing by rotating the advance unit.
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Old 10-22-2013, 11:10 PM   #13
Rob Farmer
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The cams do eventually wear. The points ramp on my 100/7 is worn to the point that I've extended the slots in the points plate to get a little more adjustment. There's also a groove worn where the seal runs on the cam so there's always a slight misting. Replacement is the only option, the bikes covered over 200k so it's no big deal

Be selective over the points and condenser that you fit the quality of these has gone down dramatically over the past few years.
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Old 10-23-2013, 08:46 PM   #14
akpasta OP
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Thanks for all the info Disston and Rob,

The advance unit seems to advance enough, it doesn't stop before F or go past F, I just can't get the static light to go on at S because my points plate won't rotate far enough. I want to know if there's something I'm flubbing with the point gap or something that can cause that, or if I need to extend the slots in the points plate like Rob is suggesting.
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Old 10-24-2013, 09:46 AM   #15
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It sounds like you need new advance springs (I think there's an echo in here )

What Rob says is also possible. How many miles on this contraption?
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