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1976 R75/6 centrifugal timing advance unit fiber washers and scratches on cam

R

randy16276

New member
Hello,
I am digging deeper into my bike than I have before and plan to do some significant work. I decided to begin with a good tune up so I would know the machine was running well before disassembly. I took off the advance unit and it was pretty grungy so I disassembled it to clean and remove old grease and crud. upon disassembly under the weights are what appears to have been 2 fiber washers. The washers for the most part fell apart. I have checked and don't see them shown in microfiche or other diagrams.

also the cam on my the unit that opens the points has some scratches on it.

I would appreciate a point in the right direction to finding replacement washers or a valid substitute. (I assume they were there for a purpose.) also guidance as to how much scoring or scratching on the cam lobe is tolerable as the advance unit is not inexpensive.

thank you for your help.

Randy
 
Randy -

Like you, I can't find any parts breakdown for the advance unit. I'm not quite at the point of going out to the garage and taking mine apart!! What specifically about these washer indicates they are fiber? seems like fiber would give up the ghost pretty quickly with the heat and all the movement. I don't recall how sloppy things were but I suppose there must be something in there to help the weights swing in/out. With a caliper you could measure the gap and find a generic washer to fit. I'm wondering if something like Delrin might be a good substitute...hard and would slide easily.

About the only picture I could find are these from EME's website...they offer advance units for sale. On one of the shots, you can actually see a washer. I wonder if they would have any ideas.

https://www.euromotoelectrics.com/product-p/bmw-ignadv626.htm
 
If replacement washers are not available from BMW or aftermarket BMW vendors then a good hardware supplier may be able to provide a workable replacement—like these at McMaster-Carr.

Best,
DeVern
 
Randy
I also had some scratches on my points lobe that was causing the points to close up.
I wet sanded it by hand with some 1000 grit then 1500 grit sandpaper until smooth
Haven't had any problems since
Nick
 
washers

Hi Randy hope you and yours are keeping well, what I did 20 or 30 years ago was to drill holes the same clearece size of the pins on the A/R unit on a plastic milk carton on the flat part and cut round to make two neat plastic washers they are still in there and yes I do remove the advance unit every so often strip clean and lube then replace just make sure the arms are not sticking due to tight washers, hope this assists Jimmy:ca
 
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re: advance unit washers

Thank you for your timely responses. Some good ideas indeed. I have sent an email with a picture of the washer on the unit to EURO MOTOELECTRICS requesting information.
also some very good suggestions as to alternatives - - a milk jug washer would not have occurred to me; that is thinking outside the jug :)

also the polishing of the cam unit sounds worth a try.

I will keep you posted as I learn more. I am planning to dig in and replace timing chain and front seals, pushrod seals, and rear main seal. so, inevitably, I will be asking a bunch of questions.

thank you again,

Randy
 
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