Fire in the hole

[R_D]

While trying to diagnose why it was backfiring, surging, lugging, and generally running like shit. My bike, an 1100RT, tried to burn itself down yesterday. It was an exciting moment to say the least.

 

First some background to the circumstances behind this problem. The last time it was ridden everything was fine. It had been a couple of months, another story all it's own, since it had been ridden. It was parked and covered under a patio awning. The spark plugs have been replaced and yes it has good fire to both sides. The old gas was drained and replaced with fresh. It is 1K away from it's 60K service. The engine temp was normal. I don't think that trying a valve and TB sync would have cured the problem. Remember it was running like a top the last time I was on it.

 

I took it out after freshening up the gas. At steady throttle it would act almost like it was running on one cylinder until something would happen and it would surge forward like a scalded dog. I rode it about 8 miles like that hoping that the fresh gas would straighten things out. Things were getting worse instead of better. When I returned you could smell and see the smoke coming from underneath the bike. When I looked under I saw the flames from the rubber center stand bumpers. All it took was one big blow and they were out.

 

It is possible that something crawled up into the pipe and clogged the catalytic converter. But I would like to hear of any alternative issues that might exist. My solution is to purchase an aftermarket exhaust or standard takeoff and hope it will remedy this problem but I don't want to just throw money at it.

 

Thanks in advance for you thoughts and insight.

[Ken H.]

Plugged exhaust is certainly a possibility. It sounds though as if it may be running extremely;y rich for some reason.

[R_D]

One plug did look fouled that we replaced. We didn't check the plugs after the test run. So that is something that I should look at.

[smiller]

Sounds like an intermittent ignition misfire in one cylinder, causing the 'on-off" power difference and allowing a lot of raw fuel into the catalytic converter... which will cause the converter to run quite hot, as you noticed. Don't run it like this as you will surely damage the converter (if it isn't damaged already.) You might have a bad plug wire or bad coil (or bad Motronic unit but let's hope not.) Could one bad Hall sensor also cause this?

[phoenixtexas]

Randy: Check for water in your gas tank. Something with similiar symptoms happened to me near Broken Bow. Wound up to be nearly a pint of water in my tank. You can drain the tank from the non-pressure hose, but there's still a quart of gas (or water) in there. Use compressed air down the filler hole under the gas cap, using a shop rag or something to make a seal and blow the tank completely dry. I'd almost bet you got H2O in there. Also, check to make sure your throttle cables are seated all the way in. You could have accidentally lifted one a few 16ths and that will make the bike act like it's running on one cylinder. Hope this helps. Tony Swindell, Howe, TX

[Ralph]

One plug did look fouled that we replaced. We didn't check the plugs after the test run. So that is something that I should look at.

 

It was the right plug that was dark & sooty. It sounded like a put, put when running. The plug fire looked a little weak, but it was outside in the light.

 

Will a 1150 rt exhaust fit his 1100 rt? I have one we could try on his bike to see what's what.

[4wheeldog]

Randy: Check for water in your gas tank. Something with similiar symptoms happened to me near Broken Bow. Wound up to be nearly a pint of water in my tank. You can drain the tank from the non-pressure hose, but there's still a quart of gas (or water) in there. Use compressed air down the filler hole under the gas cap, using a shop rag or something to make a seal and blow the tank completely dry. I'd almost bet you got H2O in there. Also, check to make sure your throttle cables are seated all the way in. You could have accidentally lifted one a few 16ths and that will make the bike act like it's running on one cylinder. Hope this helps. Tony Swindell, Howe, TX

 

Given that the bike sat ouside, I am betting the above is correct. You can siphon almost all the water out, but I think you might want to remove the tank and invert it. Good Luck!

[Ken H.]

Could one bad Hall sensor also cause this?

No. Both injectors are opened each and every fuel pulse. There is not one HAL for one cylinder and one for the other.

[smiller]

No. Both injectors are opened each and every fuel pulse. There is not one HAL for one cylinder and one for the other.

OK... but... do you mean to say that both injectors are opened at the same time (which would be the intake stroke on one cylinder but the exhaust stroke on the other)? I know about 'wasted spark' ignition systems, but 'wasted fuel'..? I must be missing something here...

[thencamebronson]

Randy,

 

Is the bike covered or is it possible for water to get in there? Also, remember the gas cap may not be sealing right. To all who responded, we checked the wires where they make the turn at the valve cover which is the most likely failure point and they were OK. The cat was definitely HOT.

 

The water in the gas thing sounds probable.

 

Harry

[powerman]

not wasted fuel but the fuel injector is fired twice every cycle. the intake valve does not have to be open to spray the fuel. it just sprays the fuel into the intake (valve open or closed). The injectors are wired together.

[smiller]

I know that the intake valve doesn't have to be open to inject fuel, but if the injector is opened (and thus fuel injected) at any other time besides the intake stroke that fuel is going to be wasted. How does the injector fire twice per cycle but not waste fuel?

[R_D]

Thanks for all the replies so far.

 

Harry the bike was covered for most of the time. I have a pup that ripped into the cover so I took it off about a month ago. The bike was under a patio roof so the only rain that could get to it was blown there.

 

It is possible that water did get into the tank. When we drained the tank the gas looked weak to say the least. I don't understand how that would make the cat get so hot.

[4wheeldog]

Anything that keeps the cylinder from lighting allows unburned fuel to pass through the cylinder and burn in the cat. Things have to be close to ideal to burn in the cylinder.......The cat is designed to burn whatever is left. If too much is left......Very hot cat! Good Luck!

[ScottB]

This may be a long shot but a lack of air in could cause a similar result as a plugged exhaust or cat. I would check the air cleaner and intake tubes. You mentioned that you had a pup. This means dog food. A while back a fellow on advrider posted picks of his F650 that had the whole air box, air filter and intake tubes packed with dog kibble. BTW it was mice that put it there. It was very funny, for us,not for him. Good luck finding a solution.

[Ralph]

Scott, we replaced the filter as one of the "maybe " fixes.

What about a bottle of gas dryer?

[Haynes]

It could have been something as simple as a piece of carbon across the plug electrodes. This would cause much of the burning to occur in the exhaust at the header junction and continue into the cat.

If the behavior has now cured itself, it would be safe to assume a plug problem but as a precaution, you should check your coil and leads that are dedicated to the fouled cylinder.

[James Clark]

I know that the intake valve doesn't have to be open to inject fuel, but if the injector is opened (and thus fuel injected) at any other time besides the intake stroke that fuel is going to be wasted. How does the injector fire twice per cycle but not waste fuel?

 

The fuel just loiters around in the intake port until the next "bus" comes along. Where else is it gonna go?

[Ken H.]

OK... but... do you mean to say that both injectors are opened at the same time (which would be the intake stroke on one cylinder but the exhaust stroke on the other)? I know about 'wasted spark' ignition systems, but 'wasted fuel'..? I must be missing something here...

Yes. Sort of. Both injectors are indeed opened at the same time. If you were to look at the schematic of the system you would see that the injectors are wired in parallel with a single control wire coming from the Motronic.

 

But it's not the intake stroke of one cylinder during the exhaust of the other. It is the intake stroke of one during the power stroke of the other. The fuel pulse to the cylinder in its power stroke just sits in its intake 'manifold' until that cylinder's next intake stroke. So no fuel is really wasted. Ed knows the correct name for this type of injection cycle, but it escapes me at the moment.

[smiller]

Ah, interesting. I has assumed that for maximum efficiency it was necessary to inject fuel at a precise time during each intake cycle (right around the opening of the intake valve), not merely at some time 'near' the intake cycle... but I guess I'm incorrect there because if the injectors share a common output from the Motronic that's pretty conclusive evidence that they fire at the same time. Thanks for the explanation.

[CMWingfield]

I don't know if this is pertinent, but a year or so ago I was hanging out at our BMW dealership and the mechanics were working on an 1150 GS that was bogging down when it was given any throttle. It would catch and run smooth for a couple of seconds, then bog down again. They changed out the fuel filter, as the bike had set up for a few months and they thought maybe some bad gas, clogged filter etc. After draining the tank and replacing the filter, they filled it up with clean gas and they opened the garage and the mechanic fired it up so as to give it a little Italian tune-up around the block. He took off with the bike bogging and catching and sputtering. After about ten minutes, he came back to dealership and you could hear that it was still missing badly. He pulled the bike back into the garage via the overhead door, and his assistant hit the automatic door closer. You could tell that something was very hot, cause you could smell it. Looking down at the catalytic converter we saw that it was glowing red hot! Needless to say, they hit the automatic door opener pronto and rolled the bike back out into the parking lot. All the while I had visions of all of us being blown up! After it cooled off, they pulled the cat and replaced it. It ran like a sewing maching. Something about the converter had gone haywire. Replacing it cured the problem.

 

I don't know if this fits your situation, but they sound similar.

 

Good luck,

Mike

[Rich_O]

the injectors share a common output from the Motronic that's pretty conclusive evidence that they fire at the same time.

 

I'm not sure about the newer ones, but on older K-bikes, all four injectors fire at the same time. The fuel just sits and vaporizes in the inlet tract until that cylinder's intake stroke.

[R_D]

Mike, thanks for relating that experience. Ralph has an exhaust from his 1150 that he said we could put on to test that theory. Can anyone chime in if it is compatible with an 1100?

[Ken H.]

Can anyone chime in if it is compatible with an 1100?

They're not the same part number, but for testing purposes, and maybe even long term, I suspect it would work.

[thencamebronson]

Randy,

 

I started on your bike last night. What do you think?

 

 

click here

 

Harry

[ShovelStrokeEd]

Rich,

 

I'm not sure about the newer ones, but on older K-bikes, all four injectors fire at the same time. The fuel just sits and vaporizes in the inlet tract until that cylinder's intake stroke.

 

Yep, that is the case for the twins as well. Nothing wrong there. Looking at the 4 cylinder at 1000 RPM idle that gives about 16.7 pulses per second 8.3 intake pulses per second or 120 msec between pulses. Not really all that long to sit around.

[R_D]

If we get another blaze going we could have turkey sandwiches all week.

 

I hope that you aren't refering to the owner. See you tonight.

[Yeeha! Stephen]

I don't know if this is pertinent, but a year or so ago I was hanging out at our BMW dealership and the mechanics were working on an 1150 GS that was bogging down when it was given any throttle. It would catch and run smooth for a couple of seconds, then bog down again. They changed out the fuel filter, as the bike had set up for a few months and they thought maybe some bad gas, clogged filter etc. After draining the tank and replacing the filter, they filled it up with clean gas and they opened the garage and the mechanic fired it up so as to give it a little Italian tune-up around the block. He took off with the bike bogging and catching and sputtering. After about ten minutes, he came back to dealership and you could hear that it was still missing badly. He pulled the bike back into the garage via the overhead door, and his assistant hit the automatic door closer. You could tell that something was very hot, cause you could smell it. Looking down at the catalytic converter we saw that it was glowing red hot! Needless to say, they hit the automatic door opener pronto and rolled the bike back out into the parking lot. All the while I had visions of all of us being blown up! After it cooled off, they pulled the cat and replaced it. It ran like a sewing maching. Something about the converter had gone haywire. Replacing it cured the problem.

 

I don't know if this fits your situation, but they sound similar.

 

Good luck,

Mike

 

Randy,

 

The overly hot converter gets my vote... Bad Converter. Sounds like the situation some of the older cars used to get by running cheap gas or leaded gas through those early converters.

 

You know how fast Texas/Ok gas goes bad if you let it sit. It will gum up my boat and yard tools in a month if you don't run stabilizer through 'em. Will do the same thing to your exhaust system.

[R_D]

Thanks for your thoughts Stephen.

 

We have replaced the exhaust and the problems still exist. The gas has been changed out. It looks like the left side of the coil is really weak. There has been some discussion that it has jumped time. Hopefully that is not the problem. I am going to get a new coil and install it next.

[thencamebronson]

If anyone is still following this sad tale, Randy, Ralph, and I futzed with it Wed night. I know what you're thinking, so please withhold any three stooges references since it was only two out of three. Exhaust did not help. Injectors had good pattern on both sides. Replaced plug wires and put on an RS coil of questionable quality. Minor improvement.

 

Randy has ordered the proper. Hopefully our local parts guy gets the right one in (about a 50% chance) we'll try that.

 

I would be surprised to learn that these can "jump timing" particularly while just sitting. Anyone have any other guesses?

[Ralph]

Sure sounds & smells like a bike out of time to me. But then again, I'm not a tech. Or maybe a bare electrical wire shorting out to the coil. ???

[Shawnee Bill]

So what's the status on your bike now?

No updates for several weeks.

[thencamebronson]

It's fixed. Don't ask any more questions, because we're not going to talk about it.

[Ken H.]

It's fixed. Don't ask any more questions, because we're not going to talk about it.

Oh come on! This one was one of the more interesting puzzlers we were all theorizing on. Reading the same old fixes all the time is no fun!

[Shawnee Bill]

It's fixed. Don't ask any more questions, because we're not going to talk about it.

 

That bad? hummm

[Eckhard Grohe]

It's fixed. Don't ask any more questions, because we're not going to talk about it.

 

Pardon! You guys came and asked for help from the group. Help was freely given. Now we ask how it went and you say you won't talk about it.

 

Your right. The next time you come for help, we shouldn't talk about it.

[No_Twilight]

It's fixed. Don't ask any more questions, because we're not going to talk about it.

 

Yes,as others have said, you owe us the solution since you asked us for help. However, your post indicates that perhaps the solution turned out to be something that you think was a stupid mistake or other silly thing that you did or should have seen. This is even more important to share with the group since we all have made stupid mistakes, will make more stupid mistakes, and need to avoid any stupid mistakes you have made for us. There is no shame in these. I've never failed to share all my problems. We owe it to each other. So share!!! glad you're back on the road, Jerry

[thencamebronson]

OK, OK lighten up.

 

I'm not the owner but I helped with the work. The first rule of troubleshooting is, or should be, eliminate the simple things first.

 

We didn't do this. It costs money and frustration when you don't.

 

The problem turned out to be the right side throttle cable was out of the adjustment nipple. Once we finally noticed and rectified this the bike ran fine.

 

Randy now has a new coil and a spare.

[Rich_O]

Thank you sir,

 

This bit of data, which came at a dear price, apparently, will save others a lot of trouble. It's not always obvious.

 

Knowledge is power. Deep breaths!

[Ken H.]

The problem turned out to be the right side throttle cable was out of the adjustment nipple.

Yup, BTDT. Thanks for the update!

[Shawnee Bill]

Hey, I figured I would find out sooner or later, and I wasn't going to tell.

But now Randy had better carry that spare on trips because if he doesn't he will need it, or someone will

[R_D]

Sorry for not posting back. I figured if someone wanted to know the outcome the thread would come back alive.

 

It's amazing how we jumped right into the complex and $$$ stuff. Then it turns out to be something so simple.

 

One used exhaust $250.00, one coil $90.00, the experience Priceless.

[TracyPrier]

You know I doubt there is anyone in our little online family, who ever gets their hands dirty working on their bike who would have made fun of this problem.

 

Heck, Many years ago I used to be an automotive engineer, supposedly taught how to fault-find in a logical, methodical manner...and I STILL sometimes dive right in suspecting all kinds of expensive and catastrophic problems to eventually find a bad connection, loose bolt, dodgy fuse or some other 5 minute, 5 cent fix!

 

The important thing is the bike is running properly again...and you have some more spares for later use

 

Cheers

Tracy