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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: bluebossa on September 16, 2018, 01:21:17 PM
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Been tweaking and test riding my fresh re-build - it's running pretty well after a full Engine swop and re-build, but once warm and on a run won't settle to idle when coming to a stop for junctions, lights etc. Researched the forum and done a few things already.. need to check Z pipe for cracks I think...
So far I've:
Adjusted and Cleaned Plugs
Adjusted Throttle Position Sensor - 0 at off and clicks, working fine
Adjusted Slow Running and Fast Running when Hot
Timing adjusted - in line with advice on here +3 degrees, pulls well
Throttle bodies synched up with Carb gauges
All connections, earths, connectors clean and greased
Starts straight after it's stalled but needs revs to keep it going on a run- seems fine cold?
Pulls like a train up to 75 mph - will sit idling fine oncee started and back in the garage - just stalls after the overun and coming to a stop.
So is it something to do with the Airflow meter when moving perhaps?
Any ideas - thanks...
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My 1992 K100RS 16V did the same thing. I never was able to find what the problem was. The last thing I tried was a new voltage regulator. Sold it shortly thereafter so no history of whether it helped. My theory was that the voltage was dropping off and killing the ECU output to the injectors.
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My 1992 K100RS 16V did the same thing. I never was able to find what the problem was. The last thing I tried was a new voltage regulator. Sold it shortly thereafter so no history of whether it helped. My theory was that the voltage was dropping off and killing the ECU output to the injectors.
Quite a few people experienced similar - reading though forum.
I've just checked Z pipe and looks in good condition... it's annoying as first ride on it today was siblime - motorway speeds, bumbling along country lanes, but once warm just kept stalling... makes for a tricky ride...
Everything is 100% tight and clean too... been through every nut, bolt, rubber and connection.
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Have you checked the Hall Effect Sensor, you can do it with a hair dryer. The tend to act up when hot.
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Have you checked the Hall Effect Sensor, you can do it with a hair dryer. The tend to act up when hot.
No, but I've got a spare HES off original Engine, so maybe swop over at the weekend.
I've just had all the Airscrews out and cleaned and reset them.
Starts perfect - and seems great when cold - tiny bit reluctant to get up above 1000 revs at first quarter turn. Ticks over lovely though.
Thanks for tip... will report
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I may be having the same or even a different issue. Starts fine, go for a ride come to a stop sign and the it doesn't wN to get going again, so I'll be watching.
Supershooter
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Ordered and received a Z Pipe - otherwise known as Crankcase Breather pipe... £10
Took the old one off, fitted and inspected it and though it looked OK when unstressed you can see cracks when it's moved...
While I can't seem to make it leak from my own lungs - who knows, this seems to affect pretty much all K75s and is a weakspot from what I have read.
Started Bike and did seem to idle solidly without any hunting so hope that's the cure - will report once I've been out on it...
Picture attached for reference
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Took the old one off, fitted and inspected it and though it looked OK when unstressed you can see cracks when it's moved...
While I can't seem to make it leak from my own lungs - who knows, this seems to affect pretty much all K75s and is a weakspot from what I have read.
How did you hook your lungs up to it?
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How did you hook your lungs up to it?
Through the hole at the front of my face :-)
I've just been out and sprayed Carb cleaner down near TB 1 and it's base where it hits the Head - Idle went way down and even stalled so bugger, must be a leak or a poor seal on the TB Rubber.
Is it a case of just getting a new one or can they be taken off and some Gasket Sealer or similar be smeared between it and head to cure leak?
Any tips - or is it just that the rubber hardens and they need replacing?
This part is £30 each new...
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Answered my own question, took TBs off, ironed out a couple of nodules, then gasket sealed and refitted.
No leaks, a run awaits
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Test rode it this morning and definitely improving but still not 100% - stalled a couple of times, though a lot less...
I took the plugs out and while 1 and 2 are nice and brown, 3 looked wet/fuelly - pics of 2 and 3 attached.
Cleaned, re-gapped and swopped out Plug 3 for a known good one.. any ideas
Couple of Videos uploading to YouTube of running and stalling for any pointers - thanks in advance...
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Well - I've done a Tank full of riding now and while it's perfect when Cold, on return legs of trips when fully warm it breaks into a slight wobbly misfire - nothing major, just enough to unsettle it when coming down to idle and occasional stalling.
I'm tweaking away, have Balanced TBs, Cured Vacuum Leak, replaced Z Pipe, Changed and Cleaned Gapped Plugs, Adjusted Slow Running, Adjusted Throttle Position Sensor - Checked mixture using Start button when running - no change in revs.
I've also swopped out Hall Effect Sensor - still the same, can't be 2 that are bust?
I'm thinking it's electrical - and one of the leads looks a bit naff and they are from 1991 - so I've ordered a set and a second hand set of coils.. en route
Anything else to iron it out and perfect it?
... otherwise Bike is brilliant, sublime to ride, easy, torquey and everything is working spot on with replacement Engine.
Be great to get some expert thinking on where you think it might be - again perfect when cold and for first 15 miles or so... develops after that and still pulls well, hit's 80mph on Motorway, seems to top out at that, but no fairing so that's probably right..
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Here's a fresh picture taken with the addition of Mirrors which arrived today and full Paniers - I love the look of the thing now - was originally an RT of course...
Thanks in advance for any ideas?
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Might be worth swapping nbr 3 injector with nbr 1 or 2, give it a good ride and recheck plugs.
If injector at fault it could have poor spray or dribbling, try cleaning with injector cleaner in tank or DIY with 9v batt/aerosol cleaner.
If fault remains at nbr 3 cylinder try your leads/coil by swapping out nbr 3 with another.
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I assume your temperature sensor is OK. Might it cause overly rich mix/flooding by failing to detect that the engine has warmed up? You could test this by pressing the start button while the engine is running and cold, then warm. If the warmed-up engine stutters or quits when the button is pressed, your mixture is too rich and the temp sensor might be faulty. At least I think I have that right.
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I assume your temperature sensor is OK. Might it cause overly rich mix/flooding by failing to detect that the engine has warmed up? You could test this by pressing the start button while the engine is running and cold, then warm. If the warmed-up engine stutters or quits when the button is pressed, your mixture is too rich and the temp sensor might be faulty. At least I think I have that right.
Hi John, Thanks - not sure re Temp sensor - could change I guess have another.
When I press the Start button on Idle - it just sits the same, no effect at all... think that's OK?
Thanks
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Might be worth swapping nbr 3 injector with nbr 1 or 2, give it a good ride and recheck plugs.
If injector at fault it could have poor spray or dribbling, try cleaning with injector cleaner in tank or DIY with 9v batt/aerosol cleaner.
If fault remains at nbr 3 cylinder try your leads/coil by swapping out nbr 3 with another.
Thanks Kiwi Don - so you think more Fueling than Ignition from your synopsis... I've put a first go of injector cleaner through - why would it be fine cold, but troublesome when warmed up though if it was an injector?
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Thanks Kiwi Don - so you think more Fueling than Ignition from your synopsis... I've put a first go of injector cleaner through - why would it be fine cold, but troublesome when warmed up though if it was an injector?
Why would you put a first go on injector cleaner if you aren't convinced an injector is at the root? KiwiDon has recommended quick test methods. Unless espresso and croissants are involved, why linger? :giggles
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No effect when start button pressed probably means fuel mixture is fine. Bad temp sensor was a long shot.
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Why would you put a first go on injector cleaner if you aren't convinced an injector is at the root? KiwiDon has recommended quick test methods. Unless espresso and croissants are involved, why linger? :giggles
Hey Laitch - I meant I've added a bottle of Redex Injection additive to a Tank of Fuel - just for good measure really - I've not taken or cleaned any injector per se.
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No effect when start button pressed probably means fuel mixture is fine. Bad temp sensor was a long shot.
Thanks re mixture - should it not still move revs up a little through enrichment, pressing the button I mean?
Temp sensor kinda makes sense if its behaving differently when hot to me... does the temp sensor alter mixture via the EFI, if so that could account for different running properties - it's lovely when cold...
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The temp sensor is one of the sources the EFI uses to determine the length of the injection pulse -- others are air mass, throttle position and RPM. Wisdom picked up on this site (forget who the source was) says:
With your engine warmed up and idling at 1000 rpm press the green starter button. If the mixture is correct the revs should stay the same or rise slightly. If the engine dies the mixture is too rich, if the revs increase significantly it is too lean. Adjustment is made by removing the rubber plug on top of the RHF corner of the air box. You need to insert a 5mm allen key. There are a couple of method for determining the mixture, one is the lean drop method, just type in lean drop method.
As the problem is temp-related, how about the thermostat? If failed, it keeps the motor cooler than it should be. Seems unlikely to be the cause of stalling when warm but as Sherlock said, "when you have eliminated all other possibilities, that which remains, however unlikely...etc"
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No effect when start button pressed probably means fuel mixture is fine. Bad temp sensor was a long shot.
Thanks re mixture - should it not still move revs up a little through enrichment, pressing the button I mean?
:twak:
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The temp sensor is one of the sources the EFI uses to determine the length of the injection pulse -- others are air mass, throttle position and RPM. Wisdom picked up on this site (forget who the source was) says:
With your engine warmed up and idling at 1000 rpm press the green starter button. If the mixture is correct the revs should stay the same or rise slightly. If the engine dies the mixture is too rich, if the revs increase significantly it is too lean. Adjustment is made by removing the rubber plug on top of the RHF corner of the air box. You need to insert a 5mm allen key. There are a couple of method for determining the mixture, one is the lean drop method, just type in lean drop method.
As the problem is temp-related, how about the thermostat? If failed, it keeps the motor cooler than it should be. Seems unlikely to be the cause of stalling when warm but as Sherlock said, "when you have eliminated all other possibilities, that which remains, however unlikely...etc"
Thanks for the explanation John, still learning and the length of pulse makes sense.
Re Starter Button - sounds like Mixture is fine - don't mess I'm reading...
Re Thermostat - I like that theory too, I've got a temp gauge on it, and it is only getting to about a 1/4 way most of the time, so maybe overcooling... time for a new one like you say... but again don't know how that would affect Running when warm... who knows though...
Beyond that I've got nearly new Plug leads and Coils on the way to try some swapping out for Cylinder 3 - will also swop injectors at the same time to see if the problem moves...
I'm also going to get the Multimeter out on the Temp sensor and see if it checks out against the troubleshooting starting graph 3,000 ohms at Ambient - down to near 0 at 100 degrees C I think - or roughly that... Hot = No resistance - Cold = Resistance in my simple mind...
Will report and appreciate your thoughts, I'm keen to iron out these last foibles on what is a splendid machine.
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I've got a theory that the third injector is not playing properly, so that when the EFI gets the Temp signal the fuel reduction, this leads to a rumble as not enough fuel it getting into a Hot Engine...
I looked into recon Injectors and found a set - this plus leads and coils should flush it out.
I also took the Bike for a run today and got it up to 8,000 RPM and just touching 85 MPH.... so thoroughly Warm
- I then measured resistance on Pin 10 at the EFI versus ground - which is the Temp Sensor signal - 270 ohms so seems good against the Curve from the starting troubleshooter
I've got a replacement thermostat on the way too, as it doesn't seem to get hot enough for my liking by the gauge.
Would expect it to reach half way, would you agree?
Pic attached
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I've got a replacement thermostat on the way too, as it doesn't seem to get hot enough for my liking by the gauge.
Would expect it to reach half way, would you agree?
It would reach halfway in a perfect world, perhaps. Gauge condition, sensor condition, coolant quality, and wiring all could have an influence on where the needle registers. I'd expect it to register somewhere in the middle third of the scale. Test your existing thermostat in water brought to a boil to determine when it opens.
If you test your moto after each component installation, we might all gain from the result, instead of using the shotgun approach and replacing everything at once.
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I just checked my Haynes manual. The OEM thermostat does NOT fail open. It stays closed and lets you know by shooting boiling water over your right leg.
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It would reach halfway in a perfect world, perhaps. Gauge condition, sensor condition, coolant quality, and wiring all could have an influence on where the needle registers. I'd expect it to register somewhere in the middle third of the scale. Test your existing thermostat in water brought to a boil to determine when it opens.
If you test your moto after each component installation, we might all gain from the result, instead of using the shotgun approach and replacing everything at once.
Thanks Laitch, I'd agree except Gauge zooms to 100% on earthing, sensor is perfect, connections clean and coolant is new. So I'd expect it to read higher and faster, takes ages to get to that level... mostly only gets to around 20% of full scale, that was after a few minutes stationary running.
Re component installation, will do - I've got the following, be good to get your prediction on which first and which, if any, cures the running!
- Injectors - refurbed
HT Leads
HT Coils
Thermostat
I will report back as and when they arrive... and I fit - what do you think?
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I just checked my Haynes manual. The OEM thermostat does NOT fail open. It stays closed and lets you know by shooting boiling water over your right leg.
Hmm - thanks John - I think it's overcooling somehow.
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I've got the following, be good to get your prediction on which first and which, if any, cures the running!
- Injectors - refurbed
HT Leads
HT Coils
Thermostat
What do you think?
There's no need to predict. There are simple tests and/or inspections on the site for each. I'd do the tests with the least effort first—the coils and the leads, then the thermostat. The injectors would be last.
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There's no need to predict. There are simple tests and/or inspections on the site for each. I'd do the tests with the least effort first—the coils and the leads, then the thermostat. The injectors would be last.
OKy doke - Wilco and will do..
I love the K75 just want it to run 100% and don't mind improving components as I go by replacing... seeking that reliability factor, I know when I get there...
Pic from yesterdays warm up run... still Blue Skies here, though getting colder..
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Your gauge reads the same as the gauges on Ilsa and Moby Brick Too. If you look at the owner's manual you will see that is where it should be. Mid scale is at the high end of the normal operating range. The upper half of the scale is where the fan is working when you're stuck in traffic on a hot day. Red is where your troubles begin.
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Where are you based by the way, and have you posted a picture of your Bike?
You've guided me quite a lot over the last year or so here, first with that troublesome Café Racer K, now my own RT... how long have you been a K owner and what other Ks have you owned?
Where I'm based is attached to each of my posts. There is a picture of my Brick in the Show Us Your Motobricks section. I've explained my history with the Brick a couple times on the site. Now that you know how to search the site, the information is yours to peruse.
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greetings...
that exposed horn is known to cause that kinda whack... you can disconnect the wiors at the relay to eliminate that component...
j o
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Just got back home after a week in Prague on Business.... reconditioned Injectors were on my desk so I just fitted and replaced the originals and took it for a 20 mile test ride.
TRANSFORMED
No stalling, no hesitating, Revved well and got to 90mph with 9k showing - super smooth and turbine like, however...
The injectors were £70 from a guy in Spain I think - reconditioned to a lovely standard and also have 4 spray holes rather than one - which seems to make a difference.
Link to eBay for sale...
https://www.ebay.co.uk/itm/BMW-K75-Motorcycle-upgrade-Bosch-fuel-injectors/132780390330?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
Runs great though and feels like 70 bucks well spent, but maybe still a tweak or two left, I guess the oirginals can be cleaned and painted, seems they needed a break from duty!
Hope that helps others with similar running issues - seems like plugs, leads and coils are all fine...
Only one slight puzzle remaining...
I took the plugs out after the Run to check how things were going in there and 2 of them are perfect, nice and dry and a good colour with number 3 a little wet - picture attached, plug on left is the one that's fuelly..
Any ideas - does that indicate over fuelling in that cylinder?
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I took the plugs out after the Run to check how things were going in there and 2 of them are perfect, nice and dry and a good colour with number 3 a little wet - picture attached, plug on left is the one that's fuelly..
Any ideas - does that indicate over fuelling in that cylinder?
According to your descriptions, that cylinder has always had a wet plug to one extent or another. Swap the plug with another cylinder and see if the condition travels with the plug.
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According to your descriptions, that cylinder has always had a wet plug to one extent or another. Swap the plug with another cylinder and see if the condition travels with the plug.
Will do - back soon...
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According to your descriptions, that cylinder has always had a wet plug to one extent or another. Swap the plug with another cylinder and see if the condition travels with the plug.
Hey Laitch - no difference on switching Spark Plug, always number 3 that get's wet. Plug fires in other Cylinders.
Weirder than that - I pulled the HT lead on 3 while it was running and it made no discernible difference to running revs??
I pulled leads on 1 and 2 while running and Bike would slow or stall... see video
I am hesitant to believe that all this time, it's only running on 2 Cylinders - could it really pull 90mph on 2 firing Cylinders - if so, then a mighty hats off to it - can't wait to ride it on 3 cylinders!
But that's what it's pointing too... would you agree?
I'm still waiting on the set of HT leads and 2nd User Coils I've ordered, but be interested on your take on this new diagnosis.
Quick Video with Sound - though I'm thoughtfully standing in front of the Camera! You can hear me shout 1,2,3 though as I pull out plugs from front of Bike(1) to back(3) - 3 no difference!
http://youtu.be/D0YITgkC5kc
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V Strange
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I am hesitant to believe that all this time, it's only running on 2 Cylinders - could it really pull 90mph on 2 firing Cylinders . . . Weirder than that . . .
Maybe the speedometer is failing, too. Test outputs of all three coils then compare. O, the tests that can be run! The engine sounds puny to me. Nothing is really weird or strange here.
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Maybe the speedometer is failing, too. Test outputs of all three coils then compare. O, the tests that can be run! The engine sounds puny to me. Nothing is really weird or strange here.
Puny? What do you mean - sounds strong to me...
Pulls well, very smooth and nice ride - Motorway speeds, definetely over 70/80 mph - which would amaze me on 2 Cylinders.
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Puny? What do you mean ...
Weak.
If it's running strong, why be preoccupied with it or solicit others' opinions about it? Run it more and often. The highway beckons. O, Bluebossa, Bluebossa Wherefore art thou, Bluebossa?
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Weak.
If it's running strong, why be preoccupied with it or solicit others' opinions about it? Run it more and often. The highway beckons. O, Bluebossa, Bluebossa Wherefore art thou, Bluebossa?
Ha - well I have some news oh wise Laitch one... "Because it is there"
I decided to have another poke around and test the Coils as you were prompting me to do to see what was happening after earlier Video confirmed No 3 was suspect.
I found a broken coil plug wire... unreal, I fixed the Earth on that coil on rebuild, but the Black and Green on No 3 Coil had snapped and was hiding away, behind HT lead - pics attached..
Got the soldering iron out, cleaned and stripped back and refitted carefully into the connector - plugged it back in, fired it back up and Cylinder3 clearly fired up for the FIRST time as the Oil and Paint started to burn off the back of the Engine and the exhaust steamed and burned off excess fuel... Conclusion - it has never fired since the Engine swop.
The plug was the Magic clue - wet = not Firing
It's been spitting fuel into that Cylinder and out of the exhaust for around 100 miles... All 3 plugs post ride now light brown... Idle had to be turned down again.
Back to the local Motorway and OMG as they say - pulled my arms off... won't talk about top speed now, but Bike is again transformed - can't believe it ran so well on 2 Cylinders and new Injectors - could have done a long trip like that... in short it is now AMAZING - revs like a Banchi - what a Bike..
Delighted... and THANKS>. P-)
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. . . can't believe it ran so well on 2 Cylinders and new Injectors - could have done a long trip like that...
Not as long a trip as you might have imagined. :falldown:
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Not as long a trip as you might have imagined. :falldown:
Why, what do you reckon would have happened?
Video now...
http://youtu.be/seDWI0Ym5LM
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Why, what do you reckon would have happened?
Overheating, coolant gushing...
Nice story - Glad I didn't see it through to the Uber part,..
I was sleeping on the mystery of where the heck does 100 miles of injections/fuel for one Cylinder end up?
- and I'm guessing at the bottom of the manifold from the Exhaust Valves - no wonder it smoked and steamed a bit when the third cylinder kicked in..
Coils and newish leads arrived this afternoon
- switched out leads as one of mine was a bit melted, I could see some arching last night when pulling them... but leaving the Coils as spares...
Couple of runs down the local highways and bighways here this afternoon, on what has turned out to be the very last of the summer in the UK - I can confirm 3 cylinders are much better than just 2 on a 75.
- 24 degrees predicted tomorrow which is unheard of in October, but the Bike really is lovely now... last Summer rides await before the Rain and the Cold kick in here..
I can now finally see why this has been called BMWs best ever Bike - great to ride, stable, smooth and great little Engine whirring away - is it a Car is it a Bike.. I now know what it should sound like.
Great machine - long live the K75... just done a small shopping errand on it... tragkorbs come in a treat.
All is well in the World... thanks for sticking with me, your challenges helped me challenge the logic and the Bike...