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Beemer100
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Germany
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Hello,

i was trying to replace the 2 little springs on my (late style) advance unit (BMW R69S) and here I go with my struggle

From the parts book I learnt that there are 2 different springs used. One is 11mm and the other I think 9mm. Plus the 9mm is weaker than the 11mm. However, there was at both weights the same long/stronger spring mounted. So, to which weight goes the long/strong spring and to which one the shorter/weaker one

How and to which extend do I then preload the 2 springs

How do I get the 2 ends of the springs over each pin ... seems like I have to bend up the ends to get it over the pins ...

thanks for your help
Klaus

P.S. The lower unit is the one I am talking about

  • fkv.jpg
Twocams
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VBMWMO #8750
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Why did your remove the old

Why did your remove the old springs? Company's spend millions of $$$ to figure this stuff out, and now its broke.

I have one of the old ones to look at if that helps? The spring locations should be the same as your old one.

twocams

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Twocams
69 R69S 03 K1200GT
92 R100RT

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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According to Vech, the short

According to Vech, the short spring goes on the side where the advance limit clip is...either "question mark" or the letter "U". The long spring then goes to the other. Maybe because on the side with limit clip, the weight has less distance to travel before hitting the resistance of the clip.

As far as preload, I'm not sure I've seen a spec. Those "preload" wings control the rate of advance by either adding or decreasing the tension on the spring. I'd start with the wings moved to essentially the same spot, maybe using the outside edge of the advance unit as a guide.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
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Advance springs

As stated in the Barrington Restoration Manual

Only the early version A have the 9 and 11mm springs
The early version B and the later version both have two 11 mm springs
Your 1st pic is a early version B
2nd is the later version so in both cases they have two 11 mm springs

I copied this from another tread that Vech from Benchmarks Works replied to one of his customers

Craig Vechorik

Vech Test on advance unit his suggestion was to place a
thumbnail between the points-THEN see if the fly weights snap back
when they are extended. They should snap back with spring action
smartly.

Cant remember how I replaced my springs
Think I had to remove the two 4mm nuts and two e clips (make note of the small nylon washers and dont let the e clip fly away)
Then install the springs and reassenble the washer fly weights and e clip then adjust the springs so they have no slack

Tommy

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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

Beemer100
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Done. Not an easy task with

Done. Not an easy task with my butcher fingers ...

Tommy was spot on. The later units only have the 11mm springs. I think I am back in business with the adv unit. Will see in September when I put it back on my R69S (the one which gets overheated)

Still thinking about the Caro Screw. Does anyone know the spec of the screw and what would be a good starting point for the trial-and-error-adjustment-journey?

thanks for your help
Klaus

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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So, Tommy, how does one

So, Tommy, how does one determine early versions A/B and the later versions?

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
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Advance Versions

My info is from the Barrington service manual page 230 (older version)
On version B and the later advance spring plate the pins are toward the outside on the spring plate using the longer 11 mm spring

I still cant post most pics but on version A the pin on the spring plate 180 from the spring plate with the limiter spring the pin is inward toward the center and uses the shorter 9 mm spring

Why
I dont know

Tommy

  • img_2555.jpeg
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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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OK, I'll check the book.

OK, I'll check the book.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Beemer100
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guess that's one of these

guess that's one of these biests. You see the different thickness of the springs and also the post which is closer to the middle ...

hope that helps

Klaus

P.S. please don't forget the advice I would need on the stop screw ... Wink

  • fkv_old.jpg
schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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As for the screw, I can't say

As for the screw, I can't say as I've seen any specs for it. You'll just need to take it to a hardware store and try screws until you find what fits. Note that you need more than the screw...you need a nut to act as a jam nut to keep the screw in place.

As far as position, I think that's going to be a trial and error thing. If you're leaving the bent spring in place, then the stop screw is nothing more than a backup to keep the engine from getting over advanced. See where your full advanced mark currently is in the window. Then install the stop screw at some position. Then recheck the full advance window. If the screw is too far out, it will be restricting the movement of the advance weights and needs to be backed off. If the screw is not far enough out, you won't see a change in your full advance mark. You would have to then move the screw until you saw where it began to affect the full advance mark.

Here's a picture of one that I snagged off the internet somewhere.

  • stopscrewmod2.jpg
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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Beemer100
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Germany
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thanks Kurt, and I think I

thanks Kurt,

and I think I remember that you have your advance unit changed like this, right? Are you happy with it? I guess by even taking out the spring, the advance curve is getting way steeper than original, right?

I would tend to leaving the spring in place und add the stop screw only to make sure the advance curve stops at 39 degrees. Currently, the F mark stays solid in the window between 3000ish to 6200 revs. Above that the F mark disappears in the window which might be one of the reasons why my R69S overheats ...

Klaus

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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Yes, I removed the spring so

Yes, I removed the spring so my advance curve relies on the strength of the two smaller springs. I haven't really noticed any issues.

6200 RPM??? My bike has never seen that kind of RPM that I know of. But it does sound like something is further bending, letting the RPM creep up.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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