senseamidmadness
Neglected Bike Adopter
[Solved] 1997 BMW R850R Sudden No Start - Not Just the Hall Sensor!
Hey folks, I'm new to BMW ownership and I'm stumped by my Oilhead. I'm a fairly experienced home mechanic and have resurrected at least three previous motorcycles from the dead, but I don't know these models as well as most of you do and I'm out of ideas. Here's the story with probably a lot of unnecessary details.
I recently purchased my first fuel-injected bike and first European bike, a 1997 BMW R850R, non-ABS, built 08/96, with 34,500 miles. This bike has lived a hard life the past few years: complete neglect in some dude's yard in Georgia, and the owner before that did other unkind things to it like installing "custom" lighting that I've since removed and stripping back the tape on the wiring harness front and rear for gods know what reasons. I've been trying to take much better care of it than they did.
I got it running about two months ago, and have put a few over 50 miles on it since then after making it safe. Lots of new or used parts to fix stuff that was broken. New fuel pump and filter, new fuel lines, replacement fuel sending unit/pump mounting plate, new spark plugs, new tires, and lots of other stuff.
Truthfully it never ran quite right. It was rough to start from cold in any temperature even with the "choke" lever and would usually run briefly, die a few times with restarts, and then eventually stay running. Only time it wouldn't do this is if it was at or near operating temperature. It didn't run particularly smoothly and the engine vibrated quite a bit, which was very noticeable at idle and got worse the higher it revved up. Not atrocious but definitely more than I expected from what I had read about Oilheads. I assumed it needed a throttle body synchronization and probably a valve adjustment and had those on the long list of stuff to do.
Last week, after putting on new tires and changing the alternator belt, I figured out how to adjust the "choke" lever cable correctly and realized it had been misadjusted such that it always had tension. After I fixed it to have just a touch of free play and lubricated the cable (with silicone oil so as to not eat the lining) and the lever mechanism, the bike then started easier than it ever had before. It died once after running for a few seconds, then kept running after the restart. I was pleased and figured I had completed one more step in getting it all sorted out.
I then did my first interstate ride on it, about 15 miles of mostly highway between 55mph and 80. It ran fine, and seemed to be a bit smoother than before. The road was a bit wet as it was very slightly raining and had been doing so all day. It didn't stutter at any point. I had also installed a fender extender so I assumed spray wouldn't get to the engine or electrics. I got to where I was going, parked the bike on the sidestand around 1AM, and then went to sleep.
The next day around 2pm, it wouldn't start. Crank and crank and crank but nothing happened. I could clearly hear the fuel pump prime and run with engine rotation. I had to go run errands so I put it back under the cover and took a car. The day after that, I got to diagnosing it. I cranked it over and it had spark on both cylinders but the spark plugs were dry. I figured that it was likely the typical failure of the original Hall Effect Sensor wiring harness and pulled that out for inspection. I did mark the position of the alternator pulley and the alignment sensor before removing them and immobilized the engine.
I opened that up yesterday and it was typical; the original wiring insulation inside the harness was totally falling to pieces. I'm pretty handy with a soldering iron and have a full toolkit for repairing electronics and wiring, so I fixed it myself -- one wire at a time, I soldered in silicone jacketed wiring and wrapped it all with automotive high-temperature foil tape. Today I installed the repaired sensor and made sure to align the parts perfectly with the timing marks I had made.
It still won't start. However, I do now have exhaust that smells like gasoline after cranking the bike, and I have strong spark on both cylinders, so I believe my repair of the Hall sensor wiring was successful. The fuel pump primes and on a freshly charged battery the bike cranks over strongly. Compression doesn't sound abnormal.
Is it possible the failing Hall sensor wiring shorted out this poor bike's Motronic brain? Could it be a bad oil temperature sensor?
I'd like to hear your thoughts.
Hey folks, I'm new to BMW ownership and I'm stumped by my Oilhead. I'm a fairly experienced home mechanic and have resurrected at least three previous motorcycles from the dead, but I don't know these models as well as most of you do and I'm out of ideas. Here's the story with probably a lot of unnecessary details.
I recently purchased my first fuel-injected bike and first European bike, a 1997 BMW R850R, non-ABS, built 08/96, with 34,500 miles. This bike has lived a hard life the past few years: complete neglect in some dude's yard in Georgia, and the owner before that did other unkind things to it like installing "custom" lighting that I've since removed and stripping back the tape on the wiring harness front and rear for gods know what reasons. I've been trying to take much better care of it than they did.
I got it running about two months ago, and have put a few over 50 miles on it since then after making it safe. Lots of new or used parts to fix stuff that was broken. New fuel pump and filter, new fuel lines, replacement fuel sending unit/pump mounting plate, new spark plugs, new tires, and lots of other stuff.
Truthfully it never ran quite right. It was rough to start from cold in any temperature even with the "choke" lever and would usually run briefly, die a few times with restarts, and then eventually stay running. Only time it wouldn't do this is if it was at or near operating temperature. It didn't run particularly smoothly and the engine vibrated quite a bit, which was very noticeable at idle and got worse the higher it revved up. Not atrocious but definitely more than I expected from what I had read about Oilheads. I assumed it needed a throttle body synchronization and probably a valve adjustment and had those on the long list of stuff to do.
Last week, after putting on new tires and changing the alternator belt, I figured out how to adjust the "choke" lever cable correctly and realized it had been misadjusted such that it always had tension. After I fixed it to have just a touch of free play and lubricated the cable (with silicone oil so as to not eat the lining) and the lever mechanism, the bike then started easier than it ever had before. It died once after running for a few seconds, then kept running after the restart. I was pleased and figured I had completed one more step in getting it all sorted out.
I then did my first interstate ride on it, about 15 miles of mostly highway between 55mph and 80. It ran fine, and seemed to be a bit smoother than before. The road was a bit wet as it was very slightly raining and had been doing so all day. It didn't stutter at any point. I had also installed a fender extender so I assumed spray wouldn't get to the engine or electrics. I got to where I was going, parked the bike on the sidestand around 1AM, and then went to sleep.
The next day around 2pm, it wouldn't start. Crank and crank and crank but nothing happened. I could clearly hear the fuel pump prime and run with engine rotation. I had to go run errands so I put it back under the cover and took a car. The day after that, I got to diagnosing it. I cranked it over and it had spark on both cylinders but the spark plugs were dry. I figured that it was likely the typical failure of the original Hall Effect Sensor wiring harness and pulled that out for inspection. I did mark the position of the alternator pulley and the alignment sensor before removing them and immobilized the engine.
I opened that up yesterday and it was typical; the original wiring insulation inside the harness was totally falling to pieces. I'm pretty handy with a soldering iron and have a full toolkit for repairing electronics and wiring, so I fixed it myself -- one wire at a time, I soldered in silicone jacketed wiring and wrapped it all with automotive high-temperature foil tape. Today I installed the repaired sensor and made sure to align the parts perfectly with the timing marks I had made.
It still won't start. However, I do now have exhaust that smells like gasoline after cranking the bike, and I have strong spark on both cylinders, so I believe my repair of the Hall sensor wiring was successful. The fuel pump primes and on a freshly charged battery the bike cranks over strongly. Compression doesn't sound abnormal.
Is it possible the failing Hall sensor wiring shorted out this poor bike's Motronic brain? Could it be a bad oil temperature sensor?
I'd like to hear your thoughts.
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