1100RT "choke" cable?

[Rollifahrer]

Mine doesn't seem to function anymore (1998). According to Clymer it should tie into the TB throttle wheel, but mine runs up under the Motronic and disappears.

I'm guessing it ties into the throttle cable splitter somehow.

Does it do anything besides hold the throttle open? I'm also guessing the (start) mixture is regulated by the Motronic based on ambient and/or operating temps.

If I'm guessing correctly, then I should be able to crack the throttle for cold starting and use the ThrottleMeister to hold a fast idle until warm.

Tank is off and I want to clear this up before putting it back together, but I have no desire to dig further and remove battery, Motronic and possibly ABS if that cable does nothing more than holding the throttle open.

I like to work on my own bikes, but "a man has got to know his limitations", and mine are electronic engine managers and ABS pumps.


thanks,

[PGlaves]

All that cable does is slightly open the throttles. There are four cables to/from the bellcrank assembly which is mounted under or ahead of the battery tray depending on model. 1= throttle cable from twistgrip; 2= fast idle (choke) cable from fast idle lever; 3= cable to left throttle body; 4= cable to right throttle body.

Unless your cable is different than mine it is adjustable. The adjuster is inside the little rubber boot on the top end of the cable beneath the clutch lever housing. If you take up any slack using this adjuster you will restore the fast idle function of the lever.

[Rollifahrer]

All that cable does is slightly open the throttles. There are four cables to/from the bellcrank assembly which is mounted under or ahead of the battery tray depending on model. 1= throttle cable from twistgrip; 2= fast idle (choke) cable from fast idle lever; 3= cable to left throttle body; 4= cable to right throttle body.

Unless your cable is different than mine it is adjustable. The adjuster is inside the little rubber boot on the top end of the cable beneath the clutch lever housing. If you take up any slack using this adjuster you will restore the fast idle function of the lever.


Thanks Paul,

I don't think it's an adjustment problem. When I actaute the lever, I hear a sound from where all the cables meet, but the throttle wheels don't move. It seems like the cold start cable broke or disconnected at that end.

The ThrottleMeister should work to set a fast idle. Ijust wanted to be sure that cable didn't run to the Motronic to change the mixture.

Thanks again,

[PGlaves]

Thanks Paul,

I don't think it's an adjustment problem. When I actaute the lever, I hear a sound from where all the cables meet, but the throttle wheels don't move. It seems like the cold start cable broke or disconnected at that end.

The ThrottleMeister should work to set a fast idle. Ijust wanted to be sure that cable didn't run to the Motronic to change the mixture.

Thanks again,

A break is possible, but not likely - given the design. I suspect that your throttle bodies are synchronized with a lot of freeplay in both cables. So when the fast idle cable turns the drum and pulls those cables, they just take up slack and don't turn the throttle plates.

[Rollifahrer]

A break is possible, but not likely - given the design. I suspect that your throttle bodies are synchronized with a lot of freeplay in both cables. So when the fast idle cable turns the drum and pulls those cables, they just take up slack and don't turn the throttle plates.


Yes, that was it. Too much slack in cold start cable and both TB cables.

I'm sooo glad I posted and didn't start taking things apart.

[Rollifahrer]

I was synching the TB's, and watching the temp gage (normal), and it quit running.

No sputtering, no loss of RPM (I was holding it around 3K), no wierd noises; it just quit.

Compression is 140-ish both sides, spark on both sides, I pulled TB's and see a tiny stream of fuel (not a cone pattern), but no obvious increase when I open the throttle as it cranks.

It will run on ether through the air box.

No signs of dirt or debris on fuel pump strainer.

Fuel from filter (22K on it) looks pristine, although it seems like a lot of pressure when I blow through it.

Cleaned and oiled air filter yesterday.

And yes, there was gas in the tank.

I'm down to pressure regulator or Motronic, but don't know how to get to or test the pressure regulator.

I like and trust my dealer (bought the bike from him), but hate not solving my own problems...is it trailer time?

Bike has 123K on it. I put 55 on with no engine problems of any kind. Always started easilly, ran well, was running even better with new plugs, valve adjustment, TB synch. I was re-synching after fixing cold start cable problem. It just quit w no symptoms...

[PGlaves]

I was synching the TB's, and watching the temp gage (normal), and it quit running.

No sputtering, no loss of RPM (I was holding it around 3K), no wierd noises; it just quit.

Compression is 140-ish both sides, spark on both sides, I pulled TB's and see a tiny stream of fuel (not a cone pattern), but no obvious increase when I open the throttle as it cranks.

It will run on ether through the air box.

No signs of dirt or debris on fuel pump strainer.

Fuel from filter (22K on it) looks pristine, although it seems like a lot of pressure when I blow through it.

Cleaned and oiled air filter yesterday.

And yes, there was gas in the tank.

I'm down to pressure regulator or Motronic, but don't know how to get to or test the pressure regulator.

I like and trust my dealer (bought the bike from him), but hate not solving my own problems...is it trailer time?

Bike has 123K on it. I put 55 on with no engine problems of any kind. Always started easilly, ran well, was running even better with new plugs, valve adjustment, TB synch. I was re-synching after fixing cold start cable problem. It just quit w no symptoms...

Change the fuel filter first.

Any chance of water in the fuel? If so - add Heet!

Is the spark regular or maybe erratic. It could be the hall sensor got too warm.

[JimMoore]

Does the fuel pump run when you turn on the key? Did you reconect the fuel lines backward?

[Rollifahrer]

Spark looks a bit weak and erratic, but I thought that was due to the way it was grounded against the fins rather than screwed in. If the Hall sensor got too warm, is it permanently damaged? The engine was cold during our last attempts to start it. Is Hall sensor replacement a DIY job?

Fuel pump and fuel lines are OK; engine was running normally.

[kgadley01]

Spark looks a bit weak and erratic, but I thought that was due to the way it was grounded against the fins rather than screwed in. If the Hall sensor got too warm, is it permanently damaged? The engine was cold during our last attempts to start it. Is Hall sensor replacement a DIY job?

Fuel pump and fuel lines are OK; engine was running normally.

If it is the Hall Sensor, its probley trailer time. Mine went out last August, and after reading my Clymers manual on replacing it. I took it to the shop. The Sensor is about $ 280.00. my final bill was $ 510.10 not bad considering everything you need to take apart to get to the Sensor. The shop charged me 2 1/2 Hrs Labor. It would have taken me a week.

[Rollifahrer]

If it is the Hall Sensor, its probley trailer time. Mine went out last August, and after reading my Clymers manual on replacing it. I took it to the shop. The Sensor is about $ 280.00. my final bill was $ 510.10 not bad considering everything you need to take apart to get to the Sensor. The shop charged me 2 1/2 Hrs Labor. It would have taken me a week.


Were there any symptoms before it quit? How did you know it was the Hall sensor? I described what happened and my troubleshooting to my dealer's tech, who thinks it could be a fuel pressure problem.

I'm getting more info on Hall sensors to study, but I'm interested hearing about units that failed.

[PGlaves]

If it is the Hall Sensor, its probley trailer time. Mine went out last August, and after reading my Clymers manual on replacing it. I took it to the shop. The Sensor is about $ 280.00. my final bill was $ 510.10 not bad considering everything you need to take apart to get to the Sensor. The shop charged me 2 1/2 Hrs Labor. It would have taken me a week.

Depending on model it can be complicated or fairly simple.

Once plastic is off - if plastic is involved. Crash bars are a pain too.

The sensor assembly is directly behind the crankshaft pulley that drives the alternator belt. To access it you have to loosen the alternator mounts and drop it down. Remove the belt. Remove the pulley. It is then accessible.

You also need to remove the tank so you can unplug the upper end of its wiring bundle.

Then put in the new one. You can time it by setting the engine to OT and rotating the crank with the pulley in place just until you hear (key on) the fuel pump run a few seconds with the timing mark just exactly at OT.

[kgadley01]

Were there any symptoms before it quit? How did you know it was the Hall sensor? I described what happened and my troubleshooting to my dealer's tech, who thinks it could be a fuel pressure problem.

I'm getting more info on Hall sensors to study, but I'm interested hearing about units that failed.

Bike ran perfect, then I washed it, bike wouldn't start. checked for spark, ( none ) checked for fuel on sparkplug. ( none ) I ask questions on this forum, and 78% of the responses said Hall Sensor. I took it to the shop and it was the Hall Sensor.

[Rollifahrer]

Thanks for all the replies and advice.

Using info from Paul Glaves, I tested it in the bike. Rotating the engine clockwise (running direction) it failed. When rotatining the crank back to try again sent a signal. Strange. So I pulled it.

Cutting away some of the heatshrink, I found the insulation on the wires coming out of the shielded cable had deteriorated. It was only 1/2" or so, but it crumbled in my fingers, all 4 conductors. Apparently the wire into the sensors is high temp wire, the harness (jcable jacket) is high temp, but the wires inside are not, and are succeptible to heat damage where they exit to conect to sensor wires. I wonder if BMW has improved this design. Using shielded conductors inside a shielded jacket seems like a good solution.

The sensors can be replaced for around 40.00 in parts IF one can find shielded wire by the foot (I found 500' spools), AND is skilled at soldering. If I could find the wire, I'd be tempted to replace the sensors, but there are a lot of places to screw up just a little and have it fail again.

Replacing the Hall sensor assembly is not a very difficult task in my garage, with bike jack, fairings already off, all my tools, good lighting, internet connection and endless supply of snacks in the house, but NOT one I would want to try along the road, on a campsite or parking lot. So I plan to buy the BMW assembly. The 240.00 I might have saved wouldn't go very far if I ever needed a tow, extra days on the road, to buy tools...and all the other stuff if my repaired unit fails again.

Lesson learned: although I was watching the RID temp gage, it only picks up temp at one point (probably oil). The Hall sensor is adjacent to crankcase and behind the alternator drive sheave, a spot that's not well ventilated to start with. I will definitely run a fan, and possibly pull the alt. belt cover off next time I let it idle to synch TB's. That's if I ever get it running again!

[JimMoore]

How long was it running?

[Rollifahrer]

How long was it running?

I lost track. Shut it down a couple times, but was trying to synch at 3K. Probably didn't let cool long enough when down.

After having it apart and seeing location of wires, I think I'll be a lot more careful.

[kgadley01]

I use two fans, its cheap insurance.

[Rollifahrer]

Part I

There was a fair amount of oily gunk under the alt. belt cover, and oil on the wires under the heatshrink. First I thought I had a leaky main seal, but I fould 2 crush washers on the breather pipe bango bolt. Guaranteed to leak oil vapor. I know oil tranfers heat much better than air, so maybe the oil on the low temp wires contributed to the problem.

Part II

The coil test shows 2 x the speced Ohms at the small pins and 1/2 at the plug wire pins. I need to replace the coil, but for curiosiry's sake, can someone give a quick and dirty why the resistance changes and what it means to the engine running properly. (Again, the engine was running very well when it suddenly died, and I would expect an out of spec coil to show symptoms over time.)

Ignorance is expensive; education is priceless...or something like that.

In hind sight, if the doubled up crush washers and oil vapor leak turn out to be the cause of the inginition trigger failure, it might have been cheaper to have the dealer change the alt. belt, which is why the breather pipe was off. I don't mind spending money for quality work at the dealer, it's the 2 week wait and the drop-off/pick-up logistics that make me read Clymer and take things apart. I guess the more I know, the more ready I am for roadside issues (which I've never had with either beemer, both used, both fairly high miles), or the more dangerous I become. I own an airhead and am aware the ABC litany that "you can't work on oilheads"...poo poo. There may be more non-userserviceable parts on oilers, but they seem to rarely fail (FD's not under discussion here!), and so far seem easy to get to and remove for testing/replacement. I'm always surpised at how intimidating a task is, until I do it the second time. Example replacing alt. belt was a huge deal the first time; getting it out of the way to get to Hall sensors was merely a mild niuisance. Same with removing tank, changing fuel filter, setting valves...Despite the ABC's death grip on nostalgia, automotive technology has moved forward, with BMW NA at the forefront. Do we need EVERY possible advance to have good reliable motorcycles? Obvioulsly not. But where would BMW Motorrad be if they had not upgraded to breakerless ignition, disc brakes, paralever, fuel injection, telescopic forks, most of which BMW invented or pioneered for use on motorcycles? Long pushrods gave way to OHC and DOHC as industry standards for power equipment a looong time ago. OK, I know about Ural and Guzzi, BUT oil-cooled boxers are starting to win races due to the combination of superior (even if less) power delivery, superior suspension and brakes, while those 2 bikes are just sort of "out there". I'm guessing the DOHC boxer will eventually be available at a reasonable price on R bikes, and that other race-proven bits will migrate over making production bikes safer and more reliable touring and sport touring vehicles. But also more expensive, you say--in 1979 my Bonnie cost 2300.00, an airhead was closer to 3300.00. That's a 30% premium. Cross shop comparable models, both Euro and Jap and you won't find anywhere near that much difference. I love my airhead, but the deeper and more often I dig into the oiler, the more I marvel at the machinery under my butt, AND the fact I fixed it myself.

Mini-rant concluded.

Thanks for all the tech support,