View single post by Jensenman
 Posted: 04-27-2009 09:01 pm
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Jensenman

 

Joined: 04-14-2005
Location: Columbia, South Carolina USA
Posts: 156
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 That will depend on the type of vacuum capsule you have. An 'advance' type has no vacuum at idle, this is the type where the vacuum tap is on the carburetor. The vacuum tap on the carb will have no vacuum until the throttle is opened (this is called 'ported' vacuum). A 'retard' type has vacuum all the time, this type will conect directly to the intake manifold.

Here's how to check for the type you have, you will need a handheld vacuum pump, a helper and a timing light. Connect the vacuum pump to the advance unit, then start the engine and aim the timing light at the marks. Now have the helper work the vacuum pump. The engine turns clockwise; if the mark moves counterclockwise with vacuum, then it's an advance type which needs to be connected to ported vacuum. If the mark moves clockwise, it's a retard type and needs to be connected to manifold vacuum.

The timing is set with the vacuum disconnected on the advance type, the retard type is left connected. Either way, you should start out with ~10 degrees initial advance and by 3000 RPM it should be in the (IIRC) 30 degree range. 

The engine running rough and the timing light 'fading' as the engine speed increases indicates to me a possible problem in the ignition module. I would want to make real sure that the optical pickup is squeaky clean where the little LED and receiver are. Don't use harsh solvents like carb or brake cleaner, a soft clean rag and a little glass cleaner should be sufficient.


EDIT: I found this page with XR3000 installation information. It has a link to a PDF of Crane's instruction sheet. http://www.bmw2002faq.com/content/view/70/32/
 

Last edited on 04-27-2009 09:34 pm by Jensenman