Wednesday, November 12, 2008

Sick Beemer

Worked under the lights last night and pulled off both BMW carbs. Took them apart early this A.M. and replaced all "o"-rings and gaskets. Also raised the main needle jets one notch to enrichen the fuel . Found one idle jet "o" ring out of place and one choke assembly gasket bad. I'm trying to chase down a high end problem which causes the engine to stumble at higher RPM (5000 to 6500). Pulled the front cover and replaced the points, then reset the timing. Bike runs and starts better but still has the high RPM problem(?) Appears not to be getting enough fuel. I'll drain the tank next and make sure the intake petcock screens are clear. Might be that some old tank debris could be clogging the screens(?) I'll just keep screwing with things until I figure it out. Want the bike running good before we head out to CA. weekend after next. I've had this problem to some degree all summer. It seems that right after I fill the fuel tank the problem is less. That might indicate that the increased static pressure from the volume of fuel in the tank over comes the resistance of the clogged fuel screens. ( I hope, sounds good in theory anyway).

5 comments:

Dano Blanchard said...

Hi There,

First, Love your blog and pictures. I actually just tonight purchased a '74 Jupiter sidecar to mate to my Dad's '76 BMW R90/6 So you can understand why I particularly appreciate your blog. I was reading about your carb /high-rev problems and I just went through something similar with my R80 ST. I had just rebuilt the carbs and after many diagnosis steps, I realized that the butterfly discs were not seating correctly. They (Bings with 2 brass screws that hold the disc to the throttle body) are very touchy to get just right seat.

In the end though, it seemed that a carb problem was only solved by endless tinkering ... then voila!

Good Luck with your carbs and wish me luck embarking on my sidecar Odyssey

Rex Blanchard said...

Hi....I too have been following your blog, thanks to my son Dan putting me on to it. As an older retired lifelong biker it's been bothering me for my 76' R 90/6 to be so under utilized. We concocted the idea of matching it with a sidecar for he and his wife making some better use of. Your blog inspired us and we both agreed that the Jupiter he found in the northwest was a great match.

He got it back to Nor Cal last night and now we await the matchup and union. We'll follow your blog as we progress with our own joint progress. BTW....we're both fellow Airheads. Keep me in mind as a hospitality contact with tools, truck, trailer in northern Utah should you need em. Best, Rex

BMW HACKER said...

Greetings Gentleman, I'd love to see a photo of your "new" Jupiter hack. Did the hack come off a BMW? Is the rig equipped with a brake? Let me know how your project progresses. D. Smith

Dano Blanchard said...

Finally got the Jupiter hack and the tug in the same garage in California... The Hack does have a cable/drum brake. The biggest challenge (now that the bike is rewired and running well and titled)
Will be the hack brake setup. We want to do a double foot brake setup as simply and effectively as possible.

Here is a short video that has teh bike and hack in it.
http://www.youtube.com/watch?v=O3kDgYCVxtQ

BMW HACKER said...

Enjoyed the garage tour....The Jupiter looks like an A-1 specimen. Mine was pretty well used ,abused and had led a rough life. I think mine was used as a toboggan (sp?)considering the look of the bottom. Let's see it when the hack is on. D.Smith

Gila Mtns.

Gila Mtns.