Does anyone have any information on the correct tension one sets the advance springs to when replacing them, the corect position for the spring anchor plate screw and the correct anchor pin position for the R50 and R60 models.I'm also looking for the correct engine timing advance data per 1000rpm.
I note from earlier correspondence on this site that the late /2 engine has a different advance mechanism baseplate where the spring associated with the advance limit stop spring does not appear to touch the baseplate( ie both springs operate in a linear mode )and that there is only one anchor pin position for each spring. Can one safely convert an earlier baseplate
R50orR60 advance mechanism
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Allan Atherton
Re: R50orR60 advance mechanism
There are two variations of the advance unit - old and new ('68-'69) - shown in a photo by Bernd Kuepper. The main difference is the leaf or stop springs.
The new advance takes two 11mm springs, and the old advance takes one 9mm and one 11 mm spring. The length of the spring is determined by where its anchor pin in located. There should be just enough tension on the springs to hold the weights closed at rest, although you can experiment by spreading the anchor plates.
I have not heard of converting an old base plate to hold the stop spring of a new base plate. I suppose it could be done by changing the stop spring's mount. All the springs of both types and lengths are available for both advance units, so I don't see a reason for converting the stop spring.
The advance per 1000 rpm would be the advance curve. This is not something that you can use, and BMW did not publish it. However, if you want to see what Klaus Wolter has taken the trouble to plot, I can email you a Word file 1.2 MB in size due to the graphics.
The new advance takes two 11mm springs, and the old advance takes one 9mm and one 11 mm spring. The length of the spring is determined by where its anchor pin in located. There should be just enough tension on the springs to hold the weights closed at rest, although you can experiment by spreading the anchor plates.
I have not heard of converting an old base plate to hold the stop spring of a new base plate. I suppose it could be done by changing the stop spring's mount. All the springs of both types and lengths are available for both advance units, so I don't see a reason for converting the stop spring.
The advance per 1000 rpm would be the advance curve. This is not something that you can use, and BMW did not publish it. However, if you want to see what Klaus Wolter has taken the trouble to plot, I can email you a Word file 1.2 MB in size due to the graphics.
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Ian MacDonald
Re: R50orR60 advance mechanism
Allan thank you for your response. Can you email me the ignition timing curve information you have.( do you need my email address?)It will assist me in making a jig to set the spring anchor position.
I noted from an earlier email of yours to this forum which showed a photo of a late /2 unit (26/5/2004) This unit had one anchor pin for the spring instear of the four options on earlier units and the metal on the baseplate where the spring rotates round it in the final 1/3 of the advance has been removed. ie both springs operate in a totally linear mode
I have modified a baseplate I had for my R60 in a similar fashion which has resulted in an improved top end performance from my bike.
I noted from an earlier email of yours to this forum which showed a photo of a late /2 unit (26/5/2004) This unit had one anchor pin for the spring instear of the four options on earlier units and the metal on the baseplate where the spring rotates round it in the final 1/3 of the advance has been removed. ie both springs operate in a totally linear mode
I have modified a baseplate I had for my R60 in a similar fashion which has resulted in an improved top end performance from my bike.