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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Puccini on February 26, 2013, 01:02:53 PM
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I have an 85 K100rt with about 30,000 on it.
I noticed that after sitting for a while, when I start it there is a small amount of gas leaking down on to the
exhaust below the head. I can see vapor coming from the rear fuel injector which leads me to believe one or more of the injectors are doing this.
It stops leaking when the bike warms up and has been ridden for a while.
What does this indicate and what can I do about it?
Gerry
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First guess would be that after 25+ years one of the fuel injector O-rings has dried out and possibly cracked.
Solution: Pull the injectors and replace all 8 O-rings as the others are suspect too.
IMPORTANT: Prior to pulling the injectors be careful to clean around their bases as crud (and maybe even some tiny rocks) has most likely collected there and will fall into the head when you pull them. Blowing that area out with compressed air should do the trick but even after you've pulled them carefully clean that crud out with out letting it fall into the head.
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Thanks for the info.
Would you know the BMW part number for the "o" rings or where I could find it.
I want to be sure I have the right item.
And any instructions on line to do the job??
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They're a generic item. BMW prices on them are ridiculous.
Given that it's an 85 with only 30k on it I'd guess that there's some varnish built up in the injectors so it might be a good idea to: Getting Fuel Injectors Reconditioned (http://www.motobrick.com/index.php?topic=1064.0)
That way you'll not only get new O-rings but know they're running well.
Probably not a good idea to ride a bike that's leaking gas onto the engine/exhaust until you've fixed it. :yow
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I think I'll take the advice and send them off to be cleaned.
I've had BMW boxer experience but never pulled and removed injectors.
Whats the best way?
Any tips?
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Click here: Removing/Installing K75/K1002V Fuel Injectors (http://www.motobrick.com/index.php/topic,3781.0.html)
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GREAT!!!!!!!!!!
Thanks very much.
One more K100 that will go on impressing others.
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Hi, not sure if I should start a new topic or it's ok to add to this one, someone will tell me if I should have done.
Never worked on injectors before and never owned a K series before last November. Mine is a 1984 K100RT with 110000 km.
I've been noticing the smell of petrol now and again- it seems to be on decelerating, for example going into a roundabout. Not sure if it's the deceleration that lets out gas, or it's there permanently and can't be smelled at higher speeds.
I hope the photos post ok and that someone recognizes the problem.
Thanks
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All those rubber bits are how old? If it were me I would replace all of them instead of trying to track down a leak. I pulled into the driveway one day and a fuel hose started spraying my leg with gas. I replaced it. Then a rubber "bushing" gave way causing a big vacuum leak. And mine's a '94. That led to this thread........
http://www.motobrick.com/index.php/topic,624.0.html (http://www.motobrick.com/index.php/topic,624.0.html)
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Wow, I wish I'd seen the problem before the nice weather started. I'll get the propane torch out next weekend and see what happens. Although judging from your experience it looks like it might be urgent. Looks like a tricky job. Did it change the way the motor ran? I can't say I notice anything wrong with the way the bike performs, although when idling I can hear a hissing noise which I don't know if is normal or not. I would imagine that an inlet manifold leak would lead to uneven idling and maybe comparing the state of the spark plugs would also show that something isn't right.
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When you have a big vacuum leak it will run like shit. I'm not saying you have one...yet....but you seem to have gas leak down there. Could be an old injector O ring giving up, hole in a gas line...whatever, but gas leaks aren't something to procrastinate on, IMHO and I personally would look at all the other rubber while I was fixing that. Not that hard to replace them and really doesn't take that long when you have the parts in front of you.
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Hi,
Is there a discussion anywhere about how this fuel system works? Maybe some exploded diagrams? I live in France and don't have the vocabulary I need in English, let alone French.
Thanks
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Is there a discussion anywhere about how this fuel system works? I live in France and don't have the vocabulary I need in English.
http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/Troubles-k100.htm (http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/Troubles-k100.htm)
A correction to the diagram for the start problems.
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It's a great link, despite the translation errors. I found the French version better after coming across several errors in English. At the bottom, there's a link to a restoration of a K100. Absolutely amazing.
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The guy behind the translation and restauration also runs a forum: http://www.k100-forum.com/portal (http://www.k100-forum.com/portal)
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Finally started today, using http://www.motobrick.com/index.php/topic,624.0.html (http://www.motobrick.com/index.php/topic,624.0.html) as my guide.
To get the injectors out it says " pull gently (yea, right) ". Taking the yea right as sarcasm, I pulled hard and the rail came away with2 injectors remaining in the head. I've given up for the evening but will have to find a way of getting them out.
Also, I was unable to see how to get the electical connections off. The tutorial says "Push down on the wire while pulling gently to remove it from the injectors."
Can anyone help me please?
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Also, I was unable to see how to get the electical connections off. The tutorial says "Push down on the wire while pulling gently to remove it from the injectors."
Use a small screwdriver and remove the wireclip which locks the connectors.
When you have removed the connector(s) from the injector(s), put the wire clip back.
When the fuel rail is removed it's only the o-rings that keeps the injectors in place.
Use compressed air around the injectors to remove as much dirt as possible,
so it don't fall into the engine.
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I finally got the last injector out with a mole grip. I notice that the hole in the cylinder head must be slightly larger than the rest: the injector on the far right (1 or 4 ?) came out really easily. I thought that the o-ring must've been more worn than the others as each injector seemed to be progressively harder to extract, the last one on the left I was unable to pull out by hand. But when I tried fitting the other injectors in the emplacement far right, I noticed that all the injectors were a less tight fit in that emplacement. Looking at the photos, the rubbers are more covered in gunge as you look from left to right. I'm wondering if all that was coming uniquely from the leaking injector on the right. Having said that, the bike was running fine. Is it possible that the hole in the cylinder head is worn?
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That looks like oil coming from the bottom of the airbox area, where the vapor hose from the block (commonly is worn/cracked) enters into. I'd take the whole upper/throttle body unit off, replace rubber seals, bushings, check hoses, etc. and clean up. Its not too bad once you get the airbox out and can see whats going on, the throttle bodies can rotate off without disconnecting the cable, although it may be easier to manipulate to clean them without the cable...
I've also had good luck with rebuilt, 4-hole spray, fuel injectors found on ebay for these bikes.
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I got the air cleaner unit out and I can see the breather pipe on the left of the picture that seems to be ok. Seems to be quite oily though in the air intake. I also noticed that one of the clamps on one rubber intake hose is loose - I can move it with a fingernail. It's at the same cylinder that also has the loose injector. I'm tempted to stop here and just put new o-rings on the injectors and replace the loose clamp. Getting those rubbers off looks difficult.
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Is that a layer of oil in the plenum (air box)?
Does the bike use oil? I'd be wondering about compression......
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No I can't say it burns oil really. Well come to think of it, I wonder if this could be a reason for smoke at start up some times, check the thread on http://www.motobrick.com/index.php?topic=2923.msg42549#msg42549 (http://www.motobrick.com/index.php?topic=2923.msg42549#msg42549)
although it seems agreed that this is caused by oil leaking at the piston rings. Hard to imagine though, that the oil in the picture would not cause smoking.
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Hi, I need some more help on this subject as something is really up. I got the bike back on the road at the beginning of April. I didn't change the intake rubbers as they seemed good, just ended up putting a screw up hose clip on the cylinder far right (N°1?). Changed the injector o-rings of course. Anyway, I was pleased with the result, my speedo was playing up but I estimated I was getting 300km before having to fuel up whereas before I was only getting 200km. I therefore have to conclude that I changed the right bits!
Well now, suddenly I get the petrol smell and only 200km on a tank full.
Today, got the left fairing lower off to have a look. Some moisture around the hoses again but particularly around the far right one. This is the one that I mentionned in an earlier post where the injector definitely was not a tight fit like the others. What could be the reason for that and could that be my problem again? Looking at the photos in my earlier post I am shocked to see how dirty the hoses are: they are nowhere near as bad as that this time.
Had the engine idling and I feel it idles well for an 85 bike with 120k km on the clock. Did the propane gas test and noticed nothing. No smell of petrol while the bike was idling, it's while riding I notice it and that's with a full face helmet and the visor closed. The red fuel warning light is playing up since I put it back together, could that be a sign? Please help!
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You should check the fuel supply lines -- tank to rail, rail to fuel pressure regulator, and FPR to tank. That's all pressurized, and if the hoses are cracked it will leak pretty much all the time. I just replaced ALL the fuel hoses, injector o-rings, the crankcase vent hose, the airbox to TB tubes, everything. Bike idles rock solid, throttle response is instant, not a hint of a leak anywhere. Totally worth it.
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Thanks the parts are already on their way. Ordered the fuel lines and the crankcase breather. There's just the small bore vacuum pipe that goes to the bottom of the regulator that I couldn't find here in France. Mine doesn't seem to be damaged, just stiff. I'm going to try softening it in detergent.
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OK now I'm really in it. :dunno2: I hope someone has the answer.
I changed the fuel lines and breathers, although I was a little sceptical about the difference it would make. The only fuel line that seemed dodgy was between the fuel rail and the regulator, but I saw no leaks. So at least I eliminated that from the equation. I left off the fairing lowers and did a short ride so that I could see straight away if the area around the injectors started getting wet or oily again. No problem, no apparent petrol smell. So today, filled up so I could start measuring fuel consumption and off I went to work. Was really enjoying the ride, but on the motorway around 20 miles from home suddenly felt wet stuff on my right leg. Looked up, no rain. Looked down and saw liquid coming out on the right hand side, could smell petrol at 80 mph. The stories of exploding bricks made me stop immediately, I'd just gone past a service station and pushed it back there. Got the tank off, and saw paint missing and bubbling from a small area, scraped at it a bit and noticed a tiny corroded spot. Jabbed at it with a screwdriver which pushed through easily. Came back after work with some kind of instant metal stuff for fixing holes patched it up, went home and came back later with the wife to pick the bike up. It started instantaneously, the orange fuel light was on as I'd drained a lot of fuel off. Went down the motorway came off and rejoined to go back the opposite direction. On the right hander coming onto the motorway, the red fuel light came on and went out as I straightened up. Normal, I thought. Then 3 miles up, I turn off, again a right hand bend and up hill and the motor just dies on me. The wife following had the the fuel I drained off in a jerry can, so I was able to add nearly 10 litres, but the red fuel light wasn't on and there seemed to be plenty already in the tank. No sign of a leak from where I filled the hole. Sat for a few minutes then tried to start, motor ran a split second then nothing wouldn't fire up. Waited again and the same thing, fires up a little then stops and doesn't even sound like it's going to start. It was now dark so I pushed it off the road and left it in a field. What could this be? Could it have anything to do with the tank leak and my reparation? Or the fuel lines I replaced? Just one thing, the return pipe from the regulator to the tank has no clamp at the tank end as I broke it getting the tank off this morning.
Desparately awaiting your answers before selecting which tools to take tomorrow. :popcorm
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Possibly some of the patch material came loose and is intermittently blocking the fuel pickup?
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That sounds logical. But as I'd had the tank off upside down and at all angles trying to get to the hole without letting all the fuel leak out, I wonder if the filter was ever cleaned or changed in the last 30 years and I've blocked things up by shaking up the crud that must be inside. Going to try and get to the filter.
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After removing the fuel filter completely, the engine finally started but wouldn't run at any constant speed, kept accelerating and dying. Switched off, heard a hiss on the exhaust pipe. Could only be petrol but how? Inspecting the injectors, I noticed a tear in the rubber intake hose on the far right. So holed fuel tank followed by airleak 5miles later.