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Timing problem – centrifugal advance unit worn out?

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Timing problem – centrifugal advance unit worn out?

Post by Kurt V »

1965 R60/2. I think the pictures below of my disassembled centrifugal advance unit tells the story. I had a persistent problem of ignition pinging whenever I accelerated in any gear. The bike always starts on the first kick, but no matter where I set the timing it continued to ping on acceleration. In addition, even though I properly set the static timing (S mark lined up, magneto Mark perfectly lined up with the V, and using an ohm meter move the points plate until the points just start to open) I could not see the S Mark with the timing light until I got up to about 2000 RPMs. And the F Mark continued to move upwards even past 4000 RPMs. So, I thought the centrifugal advance springs were worn out. Once I pulled the advance unit I saw that the advanced limiter spring was broken off.I decided to go ahead and disassemble the advance unit for a good cleaning. After cleaning I discovered the centrifugal weights mounting holes were elongated and the pins they slid over are at least 1/3 of the way worn through. Guess it’s time to bite the bullet and order a new centrifugal advance unit.

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Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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skyler.robbins
Posts: 227
Joined: Sat Sep 22, 2018 4:14 pm

Re: Timing problem – centrifugal advance unit worn out?

Post by skyler.robbins »

Wow!
Good catch there.. I bet your bike will be top notch once you install the new unit!

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jwonder
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Re: Timing problem – centrifugal advance unit worn out?

Post by jwonder »

Before you buy a new one look at my post and video here : viewtopic.php?p=74042#p74042

Find an old ome on eBay and rebuild it. It’s much better.
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: Timing problem – centrifugal advance unit worn out?

Post by Kurt V »

James, I saw your post, only after I ordered the new advanced unit! If nothing else it will give me an opportunity to see if they have fixed the problem. If not I’ll send it back and hopefully get my money returned. Then I’ll work on rebuilding an old unit.

I’ve got the equipment to do the same testing that you did on your video. Thanks for posting that!

I’m wondering, is the rest of the advance unit is still gooda? Basically what I’m thinking of doing if the run out on the lobes of the new advanced unit are out of spec, using my old piece that has the lobes on it, but use the rest of the new unit. Weights, spring, etc., As those are the parts that are worn out on my old advanced unit.
Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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jwonder
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Re: Timing problem – centrifugal advance unit worn out?

Post by jwonder »

Not sure if it is exactly the same design. I would check the lobes on your current one as well including the heights.

Please post your findings as we are all in the same boat!!
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: Timing problem – centrifugal advance unit worn out?

Post by Kurt V »

Will do!
Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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San Arthur
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Re: Timing problem – centrifugal advance unit worn out?

Post by San Arthur »

Hi Kurt.
I talked to Salis about the issues with the new batch of centrifugal advance units and he is well aware of it.

I was about to order a new set for Zenaida thinking mine were worn out but my problem was a weak points spring.

Is a cheap replacement part. Good luck!
San Arthur in San Antonio, Texas
'58 R26 '76 R90S '88 R100RS '94 R100GS/PD

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: Timing problem – centrifugal advance unit worn out?

Post by Kurt V »

Well they haven’t fixed the issue with the new units as you can see in the pictures. The pictures are the two lobes. I haven’t installed the new unit yet, but I probably will as I can’t find a serviceable used unit and mine is completely shot. Once I get it installed, I’ll measure the distance between the two cylinders for when the points open. Hopefully I won’t have more than 1/2 inch distance between the two marks on the fly wheel.

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Kurt V
R60/2, R65 LS
1973 Norton 850, 1973 RD 350

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jwonder
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Re: Timing problem – centrifugal advance unit worn out?

Post by jwonder »

Watch out, you will hurt the motor if it is too far out of time. There will be one coming up on German eBay or USA eBay some I am sure. You need to look for “ignition” and “advance” to find them.
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

Kurt V
Posts: 59
Joined: Thu Oct 15, 2020 9:13 am
Location: Lincoln, NE

Re: Timing problem – centrifugal advance unit worn out?

Post by Kurt V »

Good news! I installed the new advance unit this morning. I first made sure my S Mark was properly in the timing window, and the mark on the magneto rotor was properly matched up with the V on the points plate. I then adjusted the points using an ohm meter. The points opened at the same point on both lobes of the advance unit. While I was in there I also installed a new Emerald Isle coil and new brushes for the generator.

Holding my breath I tickled the carbs and gave it a kick. It started right up! The RPMs held steady at 900 RPM. Using a timing light I could see that the S Mark was steady and right where it should be and the advance F mark did not move beyond 3000 RPM! Again using the timing light I moved the induction pick up from one cylinder plug wire to the other. I did this just to make sure that I was getting a spark on both sides.

Now to check for differential timing. Not more than 1/8 inch difference between the cylinders! And that is well within the specs according to Duane on his website.

Took it for a ride to give the engine a good warm-up. Idled smoothly and accelerated well. When I got back I turned it off, waited a few minutes, and they gave it another kick. Started right up again on the first kick!

In conclusion, although there is a slight difference in the total height of each lobe on the advance unit (12 hundredths of a millimeter), the point at which the points opened and closed were the same on both lobes. So, for me, I’m going to stick with this advance unit. I don’t think the difference in the total lobe height really matters.
Last edited by Kurt V on Wed Aug 18, 2021 4:15 pm, edited 1 time in total.

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