Hello all!
So I am encountering a problem with my 1986 R80RT and need your help. There is a bit of background here that may be important, so please forgive the extended length of this post.
Last weekend, I took a trip from San Diego to the AHRMA Corsa Classica at Willow Springs Raceway in Rosamond, CA.
On the way up, I noticed the voltmeter had dropped into the red, so I pulled the cycle off and sure enough the battery was drained.
After pulling the tank and pushing on all the relays, connectors and such and also removing and cleaning the battery cable connections, it became apparent that this was not going to be a roadside repair.
As luck would have it, there was a BMW dealer (Irv's) in Orange, CA about 35 miles away, so I reassembled the cycle, push started and rode it over to them.
They were extremely accommodating and took the cycle right into a service bay. Within 20 minutes, the diagnosis was a failed alternator rotor. Again, with luck on my side, they had one in stock and soon the mechanic was taking my R80 for a test ride.
Shortly after his return, the service representative approached me and said the charging system was fixed, but the mechanic was not happy with the cycles performance. She went on to say that he thought one or both of the carburetor diaphragms was ruptured. Moreover, they were willing to replace the diaphragms for just the cost of the parts as I still had time remaining on my initial one-hour of labor.
The suited me fine and I authorized the repair.
Soon, the mechanic was out for another test ride and the report was good!
From there, I rode the cycle on up to Rosamond (~100 miles) and then took it on another 100 miles journey the following day after the show at Willow Springs.
The cycle performed flawlessly and the power was noticeably improved.
On Sunday, I began the ride home still very satisfied with the repairs as the cycle was running great and the charging system was working perfectly.
I stopped to refuel and have brunch and was back on the road again about an hour later.
When I hit the 15 South, the cycle suddenly stalled. It felt like it had ran out of fuel so, even though I had gone less than 50 miles, I switched to reserve as I coasted to the shoulder.
There was no indication of any electrical issues and the starter turned freely, but the cycle would not restart. After about 5 minutes, I tried again, and was surprised when it backfired loudly out of the right carburetor area and then fired up and was purring like normal.
I rode to the next exit and checked the cycle over.
A couple of things I noticed were the cycle was now dripping oil from the oil sensor (which may be a coincidence, but I include it here to provide as much detail as possible), and air bubble were flowing up from the fuel filter window on the right side.
I reseated the fuel hoses to the petcock and checked the oil and thought it best to get the cycle on home.
Back on the highway, it stalled again (symptom reminded me or vapor lock as it did not struggle on one cylinder it just stopped running). Again, I waited and again a large backfire was followed by successful and smooth ignition.
This occurred several more time on the ride home (~120 miles) and I stayed in the right lane so that I had easy access to the shoulder. The symptoms were always the same.
On Tuesday, I called the BMW in Orange and was told that it sounded like a problem with the hose from the tank vent being constricted. They wanted me to bring the cycle in but they are up in Orange and I am in San Diego. That said, they asked if I would check the vent hose and remove it if needed.
That evening, I pulled the tank and there is no vent house just the nipple on the tank where it would go. This leads me to believe that the hose had been missing for sometime. Since, the tank is vented, I am working with the theory that the tank is venting fine.
So, as of now, this is where things stand. The oil sensor is still leaking oil, and the stalling has not been fixed.
Just a little extra information, neither carburetor is over-flowing, though I have not pulled of the bowls to check the floats. I find it odd that the cycle stalled on both cylinders because if there was a problem with one carburetor, I would have expected to lose one cylinder and not both.
The cycle just shuts down but, so far, has always restarted about being off for a few minutes. Once restarted it runs fine until the next sudden stall.
That is all I can think of at this time. As this forum has always been a great help to me (especially when I bought my first 1979 R65), I turn once again to all of you for help in resolving this latest issue.
Thanks in advance!
Bill
