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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Lbxpdx on August 25, 2023, 12:46:26 AM
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I’m trying to figure this out. For a while I have noticed that at speeds roughly 40 and above I get this feeling, as if the wind resistance is higher, then it disappears. It happens relatively rhythmically. I changed the fuel filter, the plugs, checked the temp gauge, has the injectors cleaned by a shop, adjusted the TPS, replaced the fuel lines, the Z hose, cleaned/rebuilt the ignition, and ran Techron and non-ethanol fuel for a few tanks.
Earlier today I decided to check to see if the symptoms were present when in neutral, and there is a burble/popping that happens from 2K and up. I tried carb cleared around the TB’s and nothing happens when I press the starter button when running.
The hall sensor is lined up to the factory notch. I’m leaning toward plug wires, but as far as I know the only way to check them is to replace them.
Any ideas or items for me to check?
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Would you describe what the engine is doing a bogging down for a moment when the throttle is opened?
Have you checked the valve clearances and balanced the throttle bodies?
Also, what is the resistance between pins #10 and #13 on the big connector that goes to the Jetronic unit? Measure when the engine is cold(~2500 ohms) and again at operating temperature(~250 ohms).
What is the fuel pressure in the rail? Should be approximately 35psi.
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I changed . . . the plugs, checked the temp gauge, cleaned/rebuilt the ignition . . ..
Does "temp gauge" = coolant temperature sensor? "What is meant by "rebuilt the ignition?"
Have you done the basic clutch adjustment including 4mm freeplay at the joint of the clutch hand lever and its housing?
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I have not checked the valves yet nor fuel pressure. I’m going to grab feeler gauges shortly and a manometer.
It might say it feels bogged down, but ever so slightly and only above 40mph.
Temp switch resistance has been verified both hot and cold.
Throttle bodies were synced 2k ago at a dealer, prior to my ownership. I double checked them with my carbtune.
Temp gauge does mean temperature switch. Rebuilt ignition means I took the ignition switch apart, cleaned it with DeOxit and put it back together.
I have done the clutch adjustment, but I did not do 4mm of free play. The clymers calls for 1.5-2mm of free play for the k75.
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. . . I did not do 4mm of free play. The clymers calls for 1.5-2mm of free play for the k75.
You're right about that. The 1994 K75 Rider's Handbook shows 4mm for the adjustment. Maybe specs changed; maybe accuracy took a holiday when it was realized that the K100/K75 line was going the way of the passenger pigeon one year or so after the handbook was printed. :laughing4-giggles: Regardless of which measurement value is chosen, the intent of free play is to completely engage the clutch when the lever is released and completely disengage it when the lever is pulled.
If there is too much free play, shifting could become stubborn. If there's not enough free play, the clutch is not fully engaged when the lever is released, can prematurely wear, and can slip at speed. To some riders, it could seem like a headwind is interfering with acceleration. It can be a subtle feeling. Often, that subtle clutch slipping can be detected by goosing the throttle when cruising. Slippage will be apparent because the tach needle will move but corresponding acceleration won't be felt. The sensation of slippage won't necessarily be permanently felt but the corresponding excessive wear will continue.
I adjust free play while using a light pull with one finger on the lever. If the finger can move the lever to the required set distance but no further, it's good to go.
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I’ll check the clutch adjustment again then.
I followed the process in the clymer, 75mm from nipple to housing, adjust bolt until resistance and tighten locknut on rear of tranny while holding the 10mm bolt, then adjusting the free play at the adjuster on lever.
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Road test it by goosing at speed in top gear. If it slips, you'll know it.
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No slippage.
I got some new clamps for the FPR, new vacuum hose for the VPR and still no change.
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What is a VPR in this context?
It could be that desensitization therapy is in order. If you could just find an 883 Sportster with a Bassani or Cobra exhaust and ride it for a thousand miles or so, that might cure your Brick. :laughing4-giggles:
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That would be fat fingers on a phone keyboard. VPR is meant to be FPR.
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I will say the plugs look much nicer after changing the FPR clamp and vacuum line.
They were way leaner previously. These look about perfect to me.
I did go for a 70 mile ride earlier today. It felt great, despite the odd bogging/hesitation that was still present.
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I will say the plugs look much nicer after changing the FPR clamp and vacuum line.. . . . These look about perfect to me.
Nothing is more unsettling than ugliness in the combustion chamber. Latte is a perennially popular electrode insulator color. :laughing4-giggles:
Check resistance from the main ground attachment screw on the frame backbone under the tank to the battery ground cable attached to the transmission. It should be <0.05Ω. Verify that all battery and ground connections are clean and tight.
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Here is a link to a thread on the K100 forum that discusses connecting the vacuum ports on the throttle bodies together.
It helps with some of the throttle response issues that seem to be especially prominent on the K75 engine.
https://www.k100-forum.com/t15212-vacuum-modification
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Well, I don’t think it’ll solve my problem. I will try creating a vacuum hose that attaches to all three throttlebodies. I couldn’t find the vacuum T’s anywhere, so I went down to the wrecking yard and pulled some off of newer Volvos wiper fluid hoses.
Design error. Worked great for off idle, but sucked in real world scenario.
I wasn’t thinking about the overall amount of vacuum, I had already envisioned the end build.
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Nothing is more unsettling than ugliness in the combustion chamber. Latte is a perennially popular electrode insulator color. :laughing4-giggles:
Check resistance from the main ground attachment screw on the frame backbone under the tank to the battery ground cable attached to the transmission. It should be <0.05Ω. Verify that all battery and ground connections are clean and tight.
I measure 0.03K Ohm, not 0.03 Ohm. Did you mean less than 0.05 K ohm?
EDIT: I cleaned the bolt and connectors at the tranny ground and now I have .1ohm resistance.
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Feels better, but still has the hesitation.
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I measure 0.03K Ohm, not 0.03 Ohm. Did you mean less than 0.05 K ohm?It feels better . . .
That is a symbol found in math, science, mechanics, and the BMW shop manual. It means less than. Others are ≤ equal to or less than, > greater than, ≥ equal to or greater than and ≈ approximately.
Your main ground connection is okay if it was measured as described. In what way does the ride "feel better."
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I am well aware what the less than symbol means. I do the majority of my responses on my phone and I rarely look for symbols.
If it helps, I am a middle school math teacher.
How does it feel better you ask? Well, I did DeOxit a fair amount of connectors under the tank, such as the FICU all the way down the ground cable.
It feels zippier above 5k. Better throttle response.
One thing of note, the temperature here,PNW, has dropped dramatically in the last week, close to 20 degrees.
My line of thinking at the moment is this: since my plugs are uniformly tan, then the odds I have a single bars HT lead is low. This leads me to believe that if it is electrical, it is either HES related or FICU.
If it is sire related, it would either need to be between the air box and the plenum as all plugs are evenly colored or it is a dirty connection at the MAS/AIR MASS METER, whatever the unit is called in the air box.
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If it helps, . . .
One thing of note, the temperature here,PNW, has dropped dramatically in the last week, close to 20 degrees.
My line of thinking at the moment is this: since my plugs are uniformly tan, then the odds I have a single bars HT lead is low. This leads me to believe that if it is electrical, it is either HES related or FICU.
If it is sire related, . . .
At this juncture, I'm uncertain what can help. :laughing4-giggles:
A drop in temperature should only effect warmup time, and that would be measured in seconds or a couple of minutes—depending on the degree of temperature change—until it was resolved on a moving moto in a decent state of tune.
Please rephrase "a single bars of HT lead is low". I can't comprehend that.
Sire related? You aren't referring to a progenitor issue there, are you? :laughing4-giggles:
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At this juncture, I'm uncertain what can help. :laughing4-giggles:
A drop in temperature should only effect warmup time, and that would be measured in seconds or a couple of minutes—depending on the degree of temperature change—until it was resolved on a moving moto in a decent state of tune.
Please rephrase "a single bars of HT lead is low". I can't comprehend that.
Sire related? You aren't referring to a progenitor issue there, are you? :laughing4-giggles:
The odds that I have a single bad HT lead is low.
I will admit that I generally respond right when I wake up if a response was posted overnight, which means I have not had coffee or I am not fully awake yet.
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I agree with those odds.
I'm not fully awake until midnight; by then I should be back in bed. 177381
Regardless, your description of this fault makes it seem a minor and transitory one, to me anyway. My tolerance for imperfection in machinery is a high one, especially if I'm enjoying myself when it's happening. :laughing4-giggles: If you installed new spark plugs right out of the box without checking the electrode gap, I suggest you recheck them and set them if they aren't to spec. They are often variable from the factory.
Maybe one of the Brick whisperers here like Scott_, frankenduck, Mighty Gryphon, daveyson et al. would like to deep dive with you on this one. Without a sound recording of your engine's presumed flaw, my advice is to devote a few minutes of spare time regularly to cleaning all electrical connectors with DeoxIT D5 if you haven't done that already.
If your Brick keeps up with traffic and gets somewhere in the neighborhood of 40-50 mpg on the road, enjoy it while you have the physical strength and time because those can be fleeting when we least expect them to be.
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My first thought was maybe check the fuel pressure, but that question was already asked.
One thing of note, the temperature here,PNW, has dropped dramatically in the last week, close to 20 degrees.
You might have excessive condensation in the fuel tank, especially if it was stored for a while with a low fuel level, and if you never use ethanol blended fuel. Water in the tank might have caused your replced filter to swell and partially block. If it's hard to blow through, that might be why. If stored for a while, I think it's good to keep the tank full. Sometimes I use ethanol blend to absorb any water that might be in the tank.
Condensation probably isn't a problem where the weather is always good, but your latitude is like cold, sunny, cold Victoria.
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I’m leaning toward plug wires, but as far as I know the only way to check them is to replace them.
If they're leaking a bit, it would make a snapping sound. I don't thinks it matches your symptoms though. Not the first time it's been said, but if you look at them under acceleration on a dark night, you might see sparks, a very dark night, darker than a black steer's bumhole on a moonless prairie night.
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. . . darker than a black steer's bumhole on a moonless prairie night.
It gets lonely at night out on the prairie, or so I've heard. :laughing4-giggles:
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Darkness warshed over him when he went to the dark side.
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Darkness warshed over him when he went to the dark side.
That could actually have been a drenching in sheep dip.
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Actually I should have said darkness warshed over the dude, without even going to the dark side.
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You're such a stickler for details. 112350 Your prose fully conveyed the salient point—it's dark in there, wherever it is. :tinhat2:
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I felt like posting the YouTube clip, but I found the will power to resist the urge.
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I installed NGK plugs and wires last night and I’m hoping to take the bike for a spin later today. My plugs looked great, a nice tan color, but I figured since I couldn’t test the stock plugs, I should probably buy some that could be tested. I did notice a difference when goosing the engine in neutral, with it responding much smoother and faster than before. I will report back later today.
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Did you measure the electrode gap before you installed them? Did you measure the gaps of the plugs you removed?
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I did measure the new plugs and if I recall the old plugs were in spec too. The old plugs were Bosch.
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Did you measure the electrode gap before you installed them? Did you measure the gaps of the plugs you removed?
Do I need the terminal plugs if I’m using NGK plugs and wires?
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It's likely you will need terminal nuts. You can determine that by looking into the opening in the wire that receives the spark plug terminal. Is it the width of a bare terminal screw or the width of a terminal nut?
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Thanks. It obviously needs the terminal nut. I also found out that the NGK wires seem to lock on the terminal nut, but in actuality they need a real good push to get that “pop” when the cap seats on the plug.
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That is a typical good fit.
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Well, the plugs and plug wires didn’t change anything. Still has the hesitation and popping on acceleration.
Two things I did find out while fiddling around today.
When the bike is left on its side stand while idling, it will eventually die. I never use the side stand, so this is new to me.
Second, when I pressed the starter button while the bike was running around 1k rpm, it attempted to engage the starter button. I just recently cleaned the switch, and from my reading it the starter switch runs through the ICU. The ICU, if I am correct, should. It allow the starter to engage if the rpm is above 770.
I’ve cleaned the ICU plug with DeOxit and the grounds under the tank. Is it possible that I may need a new ICU?
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On a K75 the revs need to be over 1000 RPM otherwise the starter will engage.
Regards Martin.
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It dies if left on the side stand.
I feel that if there is water in the tank, it might double the amount of water under the pump while on the side stand cause they're both on the left.
This could be another good reason to double check if the replaced fuel filter is partially blocked.
Water in the tank might be difficult to see, especially with fuel circulated and mixed by the pump.
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It dies if left on the side stand.
I feel that if there is water in the tank, it might double the amount of water under the pump while on the side stand cause they're both on the left.
This could be another good reason to double check if the replaced fuel filter is partially blocked.
Water in the tank might be difficult to see, especially with fuel circulated and mixed by the pump.
There is no water in the tank. I emptied completely, took everything out and cleaned it. I just filled up today with Chevron 92 and I did take a peak inside with the cap off while it was running to see if I could spot any bubbles or gushing fuel.
The filter is a BMW one that was quite easy to blow through.
I feel like it runs great under 3k and that is when the popping starts and the hesitation. Maybe I need to go over the TB rubbers again and spray some carb cleaner or the like.
Many moons ago, there was this great group of airheads that would get together here in PDX. I don’t know if any brickhead gatherings in the area.
I guess I’ll keep chugging along until I figure it out.
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On a K75 the revs need to be over 1000 RPM otherwise the starter will engage.
Regards Martin.
Good to know. Thanks.
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One of the other suggestions was to check the fuel pressure, it might be low.
One of the things I'm thinking is does it only happen when the engine is warm? Or does the fuel pressure drop when it happens, like say a hose has a temporary kink, since it seems to be temporary, but dunno how long it lasts before it comes good, or when it comes good.
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One of the other suggestions was to check the fuel pressure, it might be low.
One of the things I'm thinking is does it only happen when the engine is warm? Or does the fuel pressure drop when it happens, like say a hose has a temporary kink, since it seems to be temporary, but dunno how long it lasts before it comes good, or when it comes good.
I’m hoping to get a fuel pressure gauge in the next few days.
I think I will go back and check the fuel lines, as I just replaced them with regular fuel pressure rated hose.
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The original hose has a formed 90 degree bend near the tank, check it out. If that's the problem you might be able to fix it with a spring type thing, If that fixes it, you probably don't need to check the fuel pressure.
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You should be able to borrow fuel pressure gauges at no charge from Advanced, AutoZone or NAPA. If the fuel pressure at the rail is okay, the next step is clear.
Back in Reply #1, Mighty Gryphon asked if you had checked the valve clearances. You didn't respond. It's time to get the materials together to do that; it's an essential task with a newly acquired used Brick because inaccurate clearances and poor throttle balance affect both performance and engine lifespan. Gryphon made a post describing an effective homemade balancing rig (https://www.motobrick.com/index.php?topic=9925.msg128800#msg128800). Once it is established that clearance are in spec, you'll need to balance the throttle bodies. Put this off no longer. clearance check Instructions abound. Among them is this one.
https://www.youtube.com/watch?v=bFkPnLVkxWQ (https://www.youtube.com/watch?v=bFkPnLVkxWQ)
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Fuel pressure regulator tested perfectly.
Throttlebodies have been synced.
I can’t find my feeler gauges, so I decided to order some for k bikes along with some consumables. Valves were checked at dealer and were within spec 10k miles ago.
I still feel that the idle drop when on the side stand may have something to do with the main issue.
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I think I will go back and check the fuel lines, as I just replaced them with regular fuel pressure rated hose.
Did you use special hose inside the tank suitable for being submersible in fuel, and has this problem occurred some time after you replaced the hose? If not small bits of rubber might be floating around inside the rail and/or the injectors, or along the supply and/or return line.
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Did you use special hose inside the tank suitable for being submersible in fuel, and has this problem occurred some time after you replaced the hose? If not small bits of rubber might be floating around inside the rail and/or the injectors, or along the supply and/or return line.
I only replaced the exterior fuel lines. I inspected the lines in the tank and they were fine. There has always been this light surging since I bought the bike. I’m just trying to track it down as everything else on the bike seems great.
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If, as you seem to be indicating, you can induce surging by leaning the Brick onto its side stand, that is BIG news. Replication is a key element of proving an hypothesis. All you need to do is consider which elements could be affected by gravity, or G-forces (as in the case of occurrence at speed). Pick one after another—wiring, hoses, switches, for example—and wiggle or move them attempting to cause an effect while the engine is running in neutral on its center stand.
The pedestrian element of a defective fuel pressure regulator should be resolved. Verification of work claimed to have been done, such as valve clearance measurement, should be undertaken. Many owners seem to have been disappointed by BMW service centers.
Obstruction in the air snorkel should be investigated. Another element to consider is the air flow meter. Is there obstruction in its intake; is its air temperature sensor dirty—there is a dedicated cleaner for that; is its electrical connection compromised, does the movement of its internal vane appear to drag or is the movement unregulated?
Diagnosing an ailing Brick should be an orderly process of system-by-system investigation. Preconceptions and assumptions made without sufficient depth of experience can stall resolution. It can be tedious but it should be focused. Appearances can be deceiving.
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Can I use Air Mass Meter cleaner on the air temp sensor?
I’m wondering if the barn door moves when the bike is on its side.
My school day just started, so I’ll be checking stuff when I get home tonight. I think I’m going to pull the pump and lines from the tank and check them again too.
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If, as you seem to be indicating, you can induce surging by leaning the Brick onto its side stand, that is BIG news. Replication is a key element of proving an hypothesis. All you need to do is consider which elements could be affected by gravity, or G-forces (as in the case of occurrence at speed). Pick one after another—wiring, hoses, switches, for example—and wiggle or move them attempting to cause an effect while the engine is running in neutral on its center stand.
The pedestrian element of a defective fuel pressure regulator should be resolved. Verification of work claimed to have been done, such as valve clearance measurement, should be undertaken. Many owners seem to have been disappointed by BMW service centers.
Obstruction in the air snorkel should be investigated. Another element to consider is the air flow meter. Is there obstruction in its intake; is its air temperature sensor dirty—there is a dedicated cleaner for that; is its electrical connection compromised, does the movement of its internal vane appear to drag or is the movement unregulated?
Diagnosing an ailing Brick should be an orderly process of system-by-system investigation. Preconceptions and assumptions made without sufficient depth of experience can stall resolution. It can be tedious but it should be focused. Appearances can be deceiving.
So I decided to pull the fuel pump out and check the lines. Everything was fine.
I pulled the air meter out and cleaned the port and made sure the cane moved easily.
Still the same.
Decided to spray carb cleaner around while idling and my idle dropped when I sprayed around the injector o-rings. I had them rebuilt, so the o-rings are new. They are rather easy to pull in and out. Could I have gotten o-rings that are ever so slightly too small?
The OD measures .575, 14.65mm.
I feel as though I should not be able to see the yellow when they are connected to the rail and inserted. I can get them a touch deeper when not connected to the rail.
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You found leakage. 112350 That the o-rings you purchased were the wrong size is always a possibility. Try some OEM rings if correct measurement seems elusive.
Verify that all parts of the injection assembly are present and fastened securely. Use a manual and parts fiche diagram for reference.
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Which o-rings have the 14.65mm measurement?
(https://www.motobrick.com/gallery/4/1601-080923021838.png)
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Are you seeing a loose fit on all the injectors or just one or two? It is odd that you have an air leak at the head but no fuel leaking from the injector's rail end o-ring.
Pull the injectors and put a little Vaseline on the o-rings before putting them in the head. They should be a snug fit in the bore when you install the injector. +1 on Laitch's advice to take things apart and reinstall the injectors in the head. I am pretty sure the rail should be bottoming the injectors in the head bores.
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Part #7 in the partsfiche are the o-rings with an OD of 14.65
All of the injectors pop in and out with relative ease, though it took some work to get them into the fuel rail. I pulled the whole unit apart last night, inspected everything and reinstalled it.
Can anyone verify that I should be able to see the spacer above the o-ring when installed?
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Here's an entry from the parts list of that diagram. I don't understand why there's a discrepancy at your end.
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Where did you get your o-rings? Were they included in the injector servicing by the outfit who cleaned them for you? It's puzzling to me because the o.d. you measured is actually larger than the stock o-ring.
Were the injectors a tight fit in the head before they were sent out for service?
Take one of your injectors to the local NAPA and ask for new o-rings. I bought a box of 10 for something like $8. It even included a tool to install them.
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The O-rings were included in the service. On my way to work I was thinking that I did not measure the ID of the O-rings, and that there might be a slight possibility that they are larger than necessary, causing the O-rings to compress and not make a perfect seal.
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The O-rings were included in the service.
When were the o-rings measured—before installation into the head, or after the leak was found? Did you moisten the injector o-rings before inserting the assembly into the head? Did you check torque of the rack's mounting screws while tightening them?
As far as o-ring dimension discrepancies are concerned, sometimes it only takes fractional differences to screw up an assembly's function. 177381
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It's normal if you can see the spacer above the o-ring when installed.
One of my bricks had a loose rail due to worn out rubber washers under the rail, it seems to be number 10 in the above drawing. From memory it didn't cause a problem but maybe it was small and not easily noticeable. I changed them cause it felt horrible having a loosey goosey rail.
The rail on my K100 is secured with bolts, not nuts as in that drawing, that makes me wonder a bit about that part of the drawing.
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When were the o-rings measured—before installation into the head, or after the leak was found? Did you moisten the injector o-rings before inserting the assembly into the head? Did you check torque of the rack's mounting screws while tightening them?
As far as o-ring dimension discrepancies are concerned, sometimes it only takes fractional differences to screw up an assembly's function. 177381
Measurements were made after the fact. I did not lubricate them nor did tighten the rail bolts to torque spec. Unlike the image, mine are bolts that thread into the head.
I did just measure the ID and they are indeed larger, .325 vs .296(7.52mm), than spec. I’m going to see what I can find at the parts store.
Side note, what is this vent for?
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The rail on my K100 is secured with bolts, not nuts as in that drawing, that makes me wonder a bit about that part of the drawing.
To whom it may concern: There is no nut in the rail fastening assembly of that drawing.
#8 is the rubber grommet vibration damper that seats within the mounting bracket hole; #9 is a sleeve bushing that fits within the grommet to receive #11–the mounting screw (bolt); #10 is a washer that is placed on the outboard side of the grommet; and #12 is a spring washer that bears on the washer to provide tension on the mounting screw to keep it from backing out during engine operation and to supply resistance for a torque value that will secure the assembly but won't crush the grommet reducing its damping ability.
At this time, it could behoove Lbxpdx to take a census of those parts to verify all are present, in good condition, and installed in the correct order. The rubber grommets should not be soft but they should be replaced if they are soft. Moistening the o-ring allows the ring to overcome resistance the head casting might create during installation. Most fasteners should be torqued to spec unless you've developed a sense of the correct torque from experience.
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Side note, what is this vent for?
That vent was part of an emission scheme. A hose attached to a port beneath the fuel tank transmitted fuel vapor from the tank into the crankcase. That vapor would be transferred to the air box via the z-tube and would be part of the combustion chamber air stream. The hose had a one-way valve in it that would open when fuel tank pressure reached a set level. Vapor would travel down the tube, and Bob's your uncle, only Bob turned out not to be your uncle, but instead became a distant, demented, inbred cousin, so the scheme was abandoned and BMW issued a service bulletin with instructions to cap that port in the crankcase and redirect those vapors from the fuel tank port into a hose that would exit behind the right footpeg plate, or go directly from the port into an air accumulator mounted on the frame beneath the port.
For those owners who are emotionally disabled by the threat of tedium, frankenduck has created this useful page (http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/thecup/thecup.htm) concerning the art of air accumulation.
Stick a piece of hose on the crankcase port, stick a tight-fitting bolt into the hose, and clamp the hose to the port so it won't fall off, or just double over the hose and clamp it to the port, or put a tight-fitting rubber cap on it.
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Well, I stopped at O’Reilys and they had a set of cometic injector o-rings in the correct size. The o-rings that came from the rebuild are rather pliable compared to these. The new o-rings snugged up much better in the ports. I’m happy to say that the majority of the surging feeling is gone.
I would still like to change the clamps from the TB to the plenum as I could rotate, not super easy but with one finger, the oetiker clamps. I’d also like to change out the exhaust gasket and the copper header washers.
I’m not sure what to attribute the overall feeling of the bike, it is smoother and revs easier. I’m sure it is a healthy combination of the o-rings, plugs, plug wires and a cleaning of the air meter path.
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The bolt is shown on the wrong side in the drawing, and also on the Clymer drawing (page 232) so somebody has been copying from somebody.
Capping off that vent will also be an improvement, if you haven't already.
Do you get any backfiring on overrun?
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The bolt is shown on the wrong side in the drawing, . . ..
The source of the drawing I posted was MaxBMW's parts fiche—one of a couple of differing BMW parts fiche arrays at various vendors that have the same drawing. At this hour, some reasons I have developed for that anomaly are:
a) When the drawing was exploded, the dashed line was flopped and the rail inlet was displaced by the concussion.
b) Technical editors and proofreaders had not been hired before the date of publication.
c) All are fallen from the Garden and none is without sin.
It certainly could account for complaints by people who used it as assembly instruction that the inlet hose was too short to reach the inlet and their injector assemblies kept falling onto the garage floor because there were no threads for the screws to engage, but I haven't read any of those yet. :laughing4-giggles:
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My theory is that they were drawn in a dark room after a spiked black Russian, and there was nooooooooo bottom.
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. . . a set of cometic injector o-rings . . ..
Did they look like the Hale-Bopp without its streamers?
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The hunt continues. Since I last posted on this thread I have checked the valve clearances, everything is perfect and today I replaced the Cooper exhaust crush gaskets. Everything I have done so far seems to have helped incrementally each time, though the problem is still present. The only part in the air system that I have not looked at or replaced so far are the rubber boots between the plenum and the head.
I think the crush washers helped quite a bit though. With my exhaust off, I did notice my exhaust valve stems were pretty white. Is this normal?
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They look okay for exhaust valves.
Did you balance the throttle bodies after you confirmed the valve clearances?
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I checked the sync a few hundred miles ago.
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There are a few reasons 75's backfire. Intake air leaks, exhaust leaks at the header to muffler junction, overly rich idle mixture, incorrect injector spray pattern, TPS adjustment incorrect and failure to close the throttle on overrun. And even with all those things corrected it may still have the occasional pop or burble. Regard it as a cat purring, it's happy.
Regards Martin.
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I don’t mind the popping on deceleration, I’ve started to pull on the clutch and coast. It’s the popping on acceleration that bothers me. I feel it is directly related to the intermittent and relatively small feeling of power loss at speed. It almost feels like the system is adjusting the fuel mixture, but it does not seem to affect the rpm or the speedometer.
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While the engine is running, carefully spray with Mapp gas all the intake components from air box to intake manifold at the engine side of each throttle body and also spray the z-tube connection between the engine and the crankcase. If you did it before, do it again. Have a piece of pie, too.
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Well I ended up taking the TB's off the bike and cleaning the crap out of them. They looked ugly from below. Slapped everything back together, synced the TB's and while my idle is steady at 1000 rpms, I still have the slight hesitation at random speeds. I did not take the rubber boots off of the TB's as I did not have the Oteiker clamp tool, fresh clamps or new boots. Now that it is getting colder, I'm not sure I want to commute in 40 degree temps 30 miles each way to save $5 in gas a day. I guess it's time to order some parts and get some new rubber bits.
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Thanks for the update.
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I know the plugs are new but mine never looked that good or lean. Mine always look like the bike is running rich and sooty (sooty black). My bike runs good but smells smokey. Not trying to hijacker you post just wondering if your lean looking plugs are the way it should be
Bill