Is this a brand new bike? My ST scared the **** out of me when it was new by giving off a smell I was sure was a wiring fire. I frantically ripped open the fake tank cover and was going to disconnect the battery, but by that time the symptoms had stopped. Long story short, it was the catalytic converter and it did it once or twice more then never again. Some sort of protective coating? I don't know.

But in my case there was no lack of power. Oh, and these bikes do not have carbs -- they are fuel injected. But yes, they are sensitive to stale or bad gas.

-dan

 

Martyn,
In 11 years of ST/GT ownership, I have never experienced or heard of those symptoms. The total sudden loss of power could be lethal in traffic ----- suggest you get it to a BMW dealer ASAP. They can hook it up to diagnostic kit and read fault codes which should give a clue. I use Allan Jefferies at Shipley, close to Leeds and have had good service.

 

If the fault is self clearing and lets the bike run again there may not be a fault code to read.
Electrical burning smells are not a good indication. Most worrisome! Good luck.

 

Just a suggestion Rontheretired. Given the burning smell that accompanies the lack of power, is it possible that the rear brake has locked on? I know that some others have had that happen after adjusting the height of the rear brake pedal (there is a brake fluid return hole in the rear brake master cylinder that remains blocked if not adjusted correctly). Don't know if it could happen on a "normally" adjusted one though. Dave

 

Thank you all for the replies, I have not had the brakes touched since the last service, but it seems like a good bet that the back wheel is locking on for some unknown reason. The problem has not reoccurred for the last 50 miles ish, so I'm going to try and forget about the whole phenomenon unless it happens again.

That said if it happens on a particularly tricky overtake I might be writing on the forum from the next life!

Suppose it all adds up to a bit of excitement...

Ron

 

What Redned said about the rear brake but even misadjusted mine only wore the pads and disk no loss of power but if it were more out of adjustment if could happen.
I've seen it happen on an Aprilia.

 

Hi Ron, last year my ST totally failed. I was on my way home from bike club when it was dark and chilly, so I had on the hand warmer, I had just passed two cars doing about 70mph when out of the blue the bike went absolutely dead. No lights so vision was only from the cars I had passed, the engine failed, just like turning off the ignition oomph. I managed to get the bike started after turning the ignition off (when I found the keys in the dark) the bike sounded absolutely rough uuurgghh, so, turned the ignition off and left for what seemed an eternity in the dark. switch it back on and started the bike, phew it sounded okay. Continued home without incident.

I put this problem on her like you. the guy's suggested everything including disconnecting the battery to check cleanliness of the terminals. All seemed okay,however a service was nearly due so, I mentioned it to the service guy who said he would check it out. On pick up we had a discussion about the problem, he reckoned that because I disconnected the battery for some time that helped to clear info required. He did say should it happen again to let him know ASAP and get the bike into him. So far no issues, but have not been too far, but I will most probably be back at bike club tomorrow, and try yo ride home in a similar manner.

Okay, someone suggested you go to your local BMW dealer, now that may not be a bad idea, tell them what happened and ask them to check it out as a matter of some urgency, let us face it your life might be on the line next time should it happen again, so that to my tiny mind makes it an emergency.

Get back to us and let us know how you get on okay.

Take it easy my friend

Flook

 

Hi Ron, last year my ST totally failed. I was on my way home from bike club when it was dark and chilly, so I had on the hand warmer, I had just passed two cars doing about 70mph when out of the blue the bike went absolutely dead. No lights so vision was only from the cars I had passed, the engine failed, just like turning off the ignition oomph. I managed to get the bike started after turning the ignition off (when I found the keys in the dark) the bike sounded absolutely rough uuurgghh, so, turned the ignition off and left for what seemed an eternity in the dark. switch it back on and started the bike, phew it sounded okay. Continued home without incident.

I put this problem on her like you. the guy's suggested everything including disconnecting the battery to check cleanliness of the terminals. All seemed okay,however a service was nearly due so, I mentioned it to the service guy who said he would check it out. On pick up we had a discussion about the problem, he reckoned that because I disconnected the battery for some time that helped to clear info required. He did say should it happen again to let him know ASAP and get the bike into him. So far no issues, but have not been too far, but I will most probab hily be back at bike club tomorrow, and try yo ride home in a similar manner.

Okay, someone suggested you go to your local BMW dealer, now that may not be a bad idea, tell them what happened and ask them to check it out as a matter of some urgency, let us face it your life might be on the line next time should it happen again, so that to my tiny mind makes it an emergency.

Get back to us and let us know how you get on okay.

Take it easy my friend

Flook[/QUOwTE]
Cheers for the info Mr flook, both times when I lost power the electrics stayed on, that's why I was thinking the back brakes may be a feature.

I did a 40 mile ride today and took the bike to the red line a couple of times to try and make the problem happen again, with my helmet camera on, but the bike ran perfectly well!

If I get to the service date in June or July I'll tell them about this phenomenon and here's keeping my fingers crossed it will not occur again

 

Martin of Rontheretired, no need to call me Mr Flook, though I thank you for that.

One thing you have not said/mentioned is this, when your engine stalled or lost power you say "I was thinking the back brakes may be a feature", this being the case, did your bike go into a skid! also did you check the rear wheel rotation by being able to push (manually) the bike! okay if you did not skid and were able to push the bike manually, that tells me the back breaks did not seize or bind on break pads to break disc, so that rules out the rear break. Also because the drive is belt if the rear end did seize up, the engine would still in in drive mode and this would affect the drive belt.

Personally I would not want to wait, I would want to know the reason and if it can be rectified to have it carried out. This though is up to you my friend.

Flook

 

My experience sorta matches yours. Loss of power, and smell. Turned out to be rear brake overheating, expanding.
I had fiddled with brake adjustment some time earlier, and learned you can't mess with that. Rear brake master cylinder fluid passage way very sensitive.
My episode was on my old ST years ago. I bet i could reproduce the problem on the GT pretty easy.
If that's your case you probably boiled your fluid. Change it very soon!

 

Gary, I bet when you touched the break disc it burnt, or you could not get your hand near enough because of the heat! Also you had to wait a fair time to allow the disc to become cold before you could ride it? Many years back, I thought I knew better! so I adjusted the pads nearer the disc, went about nine miles could smell burning and despite trying to accelerate the bike done the opposite. Bike went on side stand, removed helmet and went sniffing around (most probably looking like a right pratt, man sniffing his bike what is he on). anyway, smell coming from back breaks, went to touch disc and the heat was awesome, could not move bike forward or back, had to wait around 20 minutes before I could do a thing. I manged to slacken the breaks off a tad and I have never ever touched them again. Now however, I have padded up the break peddle so my foot movement is not too far. A much better solution. Flook

 

Same thing happened on my CB1100. Removed the brake pads and they were definitely burned and crumbled. I have no idea what happened but have had no issues since replacing them.

Sent from Motorcycle.com Free App

 

10/4 on that guys.

 

Right, the bike came to a halt again yesterday, was doing about fourty and I managed to ride the bike onto the pavement. The engine was still running okay but it felt like I'd put my foot on the rear brake pedal.
Put the bike on the centre stand and the rear wheel was solid, the brake had seized on!
I manually turned the wheel whilst operating the rear brake pedal with my other hand several times, and in one giant step the wheel was free!!
I tested the pedal a couple of times and it worked okay, so I jumped back on the bike and rode the thirty miles home with no further problems.

Since this phenomenon originally happened I have done several hundred miles with no hassle. I am at a loss to understand why this is happening?

Any thoughts? Or suggestions as to what I should do or check?

As a last resort I could take it to the dealer and part with a load of cash!!

Why would this happen out of the blue, surely if the brakes were faulty they would be faulty all the time, not just at random intervals?

I hadn't used the brakes for a good three or four miles before they locked on by the way.

Perplexed!!

Ron

 

Brake fluid bottle all as usual and no sign of leakage at the brake.

 

Did you by any chance attempt to adjust the brake pedal height by messing with the threaded rod that goes into the rear master cylinder? BMW says this is a big no-bo because incorrect adjustment will prevent the relief port in the master cylinder from opening, locking the brakes on. It also makes almost no difference in pedal height and is not meant to be an adjustment for that.

-dan

 

Nope, haven't touched the brakes at all, and at the last service there was hardly any wear on the pads and the discs both front and back. And I very rarely use the rear brake in normal riding, the front brake usually being enough to pare off excess speed. The bike has only been serviced by the dealer since new, all I do is clean it and ride it!

 

Martyn,

How old is the bike? Are you the first owner? I have to wonder if somebody did mess with that adjustment at some point and it is so close to blocking the relief port that under certain circumstances it will lock up once you apply the brakes -- which is classic relief port blockage behavior. I ruined my rear disc this way, so I'm not pointing fingers. ;-)

-dan

 

When was the last time you bled the brakes? This can be a big problem.

 

Had bike since new, 2013, only owner, I presume the brakes were bled last service? Which was approximately 7 thousand miles ago.

Do you think it would be a good idea to bleed brakes? And if so how do I do it? Can't be rocket science can it! I'm pretty good on the diy front so if anyone can point me to a step by step guide for the 800 GT that may be worth a try?

And thanks for the thoughtful replies so far,

Ron

 

Ron - I suggest you check the pedal free play and adjust to spec as necessary. Like Dan says, sounds like it’s just on the limit of closing off the passage between the master cylinder and the reservoir. Friction from pad drag can create heat, expanding the disc and reducing clearance, creating more friction, more heat etc until the brake locks.

Brake fluid change schedule is time rather than distance based; after the first 12 months then each 24 months thereafter.

 

What Mark said. Plus, bleeding is very unlikely to change anything. Air in the system causes mushy pedal and the need to pump the pedal to get much braking action. It would not cause lockup.

When you do the adjustment, err on the side of a little too much play and do some test riding.

-dan

 

Martin, as I was reading your post a thought came to me. Have you removed your break pads since your post! I ask this as the probability occored to me the pads may not be as they should either in their position or slightly jamming in some movement, so to cause a slight interference with your break disc. If you have not removed the pads it may be a thought to check them anyway, one or both may show excess wear on the pad face!!

Like I said, I had a thought, what is the harm to check anyway.

all the best