Hey peeps,

1990 K100 RS 16v 21000 kms.

Getting ready for spring today (a little early but Trump got elected), dreams can come true.

Pulled the plugs. They are black, dry-ish, smell gassy, threads are wet.
All 4 look the same.

Suspects are 

1) TPS not reading correctly ECU says full bore.
2) I got this bike last winter had 17000 kms on the dial.... injectors are clogged with 30 years of not being ridden (fuel not atomized).
3) Starved for air... didn't change filter when I got her. (rich)

On start in the summer heat would not start without enricher (choke) and a little throttle.

Any ideas, conclusions or additions?

Jake

If the bike has only been idling from cold start, then that plug appearance could be quite normal.

But, after a good up-to-temp run, then they shouldn't be sooty.

If the bike is starting and revving out okay, then I wouldn't think your injectors are blocked. Change the oil & filter, take it out in that sunshine and thrash it, then have a look at things.

And Donald Trump knows nothing about engines. But let's not go there.

Do you idle the bike to warm it up?  There's no need for that.

From page 31 of the K100RS4V rider manual:

"Do not warm up the engine at idling speed. Move off immediately after starting."


A faulty temp sensor can cause mixture issues.



(President Trump is a stable genius. Just ask him.)

What the others have said.  (excluding the Trump comments)

The air filter is probably okay, they should be good for 50-75,000km, often more unless the bike is used off road in a desert.  What people often find are mouse condominiums in the airbox. 

It's quite possible the rings are a bit stuck from lack of use and allowing a little bit of oil to be burnt.  A couple of good rides will help that issue.  My 16V bikes both used more oil than the 2V models.  I have no idea why.

With only 21,000km, I would not be concerned that there are any real mechanical issues.  What is needed is a good clean of all the electrical connections, some Chevron Techron fuel system cleaner in a couple tanks of fuel, set the TPS, and a throttle body balance should have it running pretty well.

I have had two of the 16V K100RS now, and neither of them shows me nice tan plugs despite running like demented locomotives.

Although it's probably not something that would cause black plugs, I'd pull the injectors and have them serviced.  I do that on every K I buy these days. With only 21,000 km on the clock no doubt it has sat at some point in its life.  If nothing else it's good preventative maintenance.

In the US I use Mr. Injector who only charges $17 each. I imagine you can find a similarly priced service up in The Great White North.

I use Mr. Injector as well despite being on the cold side of the border.  Maybe Ter'anna (Toronto) has a similar service but I wasn't able to track it down.

As many of you know it's winter.

For the Black plug problem, I forgot to mention that the exhaust end is totally covered in black soot.

I have a suspicion that there is something not adjusted or working in the fuel system so i'll go over and test all the components.

I have gone over all of the connectors that I've been able to get my hands on and coated with dialectic silicone. Non of the connection had any sign of corrosion. (This bike has been garaged it's whole life). I'll continue as I get further into the guts of her.

Canadakbike wrote:As many of you know it's winter.

For the Black plug problem, I forgot to mention that the exhaust end is totally covered in black soot.

I have a suspicion that there is something not adjusted or working in the fuel system so i'll go over and test all the components.

I have gone over all of the connectors that I've been able to get my hands on and coated with dialectic silicone. Non of the connection had any sign of corrosion. (This bike has been garaged it's whole life). I'll continue as I get further into the guts of her.

I would be thinking about the air filter or choke, fast idle, it sounds like you ae running very rich.

Hi Stumpy,

Yeah, This bike is new to me and I'm committed to a general once over for all the the nick-nacks.

Read the codes and getting 1133 and 1122 both hall effect sensors not responding.
Checked at the harness and both show voltage and no voltage when triggered.

Now I have to figure out what that means????

I see you have put about 4,000km on the bike last year.  How was the engine performance?  Good throttle response?  Backfiring?  Surging idle when warmed up?  What kind of fuel efficiency are you seeing?  My 16V K100RS gets a pretty consistent 49-50mpg when commuting and riding around town.  Not sure how that works out in the metric system.

Injectors work by being powered open and closed by a spring.  The spring has less force than the electrical coil, and as a result it is possible that shutoff can be a little sluggish, resulting in extra fuel being delivered.  I ran a half bottle of Techron per tank every other tank for about 2,000 miles to loosen them up.  When they finally broke loose, the improvement was noticeable even though it was running well before.

There is a procedure for setting the Throttle Position Sensor using the Motronic.  Make sure it is adjusted properly as it has a bearing on mixture.

Hall effect codes are common with the Motronic.  If the engine runs ignore them.

I put on a good amount of KM's this year... I thought that the fuel consumption was high at 220KM  136 miles per tank.
The engine was consistent through the season with the exception of starts, and cold running. After starting the choke was not always able to keep the engine running, further the first few (10) minutes of running there was no power from a start.


 All 4 Look like this.

After the season ended I changed the oil which was dark and I only got 3 liters out. There were no signs on external leakage on seal etc.
I, of course believe that there is internal to the cylinders. The problem is that this bike has 21K kilometers so even is there had been no maintenance on this baby I still would not expect the rings to have blown. Additionally, its all 4 plugs that are this ugly.

Looking for more evidence


Nice build up of soot on the exhaust means I have to figure this out. Starting with the fuel injection system seems to make the most sense. 

As, I have the bike apart to do a handlebar swap I have access to all of the electrical under the tank.

Thanks for your input Point Seven Five, I'm getting 36 miles per gallon which is just crap.

I bought rebuild kit for the injectors so they will get a good cleaning and reliable o-rings.

I'll check the TPS static voltage today and adjust if necessary.
Same with the mass air.

I'm familiar with modern ECU's and associated sensors and modules. 

That been said, what function and by what mechanism does the CO2 Potentiometer work, what does adjusting it effect?

Thanks all,

Jake

Bricks don't like sitting around, and lack of use can cause all sorts of problems. Sticking rings and fuel injectors as well as bad electrical connections seem to be a common problem from under use. This can sometimes work itself out over more use, or you can go down the MMO or Seafoam route. As both of these products aren't available one of the US users will probably chip it on the benefits of using these products. The OZ alternative is to use a high detergent oil to free up the rings and have the injectors cleaned and thoroughly clean all the electrical connections.
Regards Martin.

Canadakbike wrote:As many of you know it's winter.

For the Black plug problem, I forgot to mention that the exhaust end is totally covered in black soot.

I have a suspicion that there is something not adjusted or working in the fuel system so i'll go over and test all the components.

I have gone over all of the connectors that I've been able to get my hands on and coated with dialectic silicone. Non of the connection had any sign of corrosion. (This bike has been garaged it's whole life). I'll continue as I get further into the guts of her.

Be careful with the dialectric stuff. Most of them are designed to keep moisture out of a connection, not to improve the contact. I wouldn't use it directly on the contacts in the connector. Disconnect the battery when you are pulling connectors apart and pushing them back together and use a good non silicone contact cleaner on the contacts.  They are put together dry at the factory for a reason. If you go to a good electrical supply shop they do have a dialectric to prevent arcing, but not really needed on these bikes.

Your over rich condition could be the temp sensor that feeds the EFI ( do a search on the site and you can find out how to check it using a Volt/Ohm meter ) sending the wrong signal to the EFI, also could be the mixture screws (Big Brass Screws ) are out of adjust or somebody has played with the throttle body adjusters.  A pretty good rule of thumb to tell if the bike is running rich is if doesn't need to use the choke to start on a cold start.

As others have noted rings need compression to work and seal properly, and on a bike that has sat for years, it will take awhile to get everything working properly. Also replace the spark plugs as it is pointless to try and figure anything out from old plugs. With the bike running use something like a timing light to establish that all the plugs are firing.Bad plugs and wires can run fine and then when under load start to break down.

I've been playing with a 86 K100 that has sat for at least 25 yrs.  No end of surprises as your work your way through stuff.  It tends to get a bit expensive

All that soot is also getting down to the rings and can make them stick, allowing some oil to get past them.  Seafoam or Marvel Mystery oil in the crankcase for a couple hundred miles may help loosen them up.  It has worked on one of my bikes.

The CO2 adjustment is made with an exhaust gas analyzer.  As far as I can tell with my 16V K100's it doesn't do anything detectable beyond small changes in the CO % in the exhaust.  I recommend leaving it alone if you don't have an exhaust gas analyzer. 

The "choke" is actually an idle speed increase that just opens the throttle butterflies a tiny bit to increase the air flow to increase the idle speed.  The throttle position sensor will detect that the "choke" has been opened, and make the corresponding correction to the fuel delivery.

My money is on sticky injectors with a side bet on the engine temperature sensor being whack or with a corroded/dirty electrical connection or ground.

36mpg certainly points to an overly rich mixture.

Through guidance from the article in the Tech pages (TPS on Motronic system). "Fuel Injector Fault Finding for Bosch Motronic by Frank Warner, I have ascertained the Following,

TPS after adjustment to .375v (pins 1 to 4 at TPS connector)

pin 31 to 13 = 700 ohms
pin 31 to 10 = 700 ohms
Pin 31 to 25 = 575 ohms

Air temperature sensor @ 20 Deg C       = 2k ohms
Water temperature sensor @ 20 Deg C   = 2K ohms

CO2 Pot

Pin 25 to 28 = 280 ohms
Pin 32 to 28 = 480 ohms
Pin 25 to 32 = 750 ohms

I adjusted the TPS to the voltage as described in post [url=http://www.kforum-tech.com/electrical/PDF/Motronic Fault Codes.pdf]Motronic fault codes[/url] moved to the tech page.


The water temperature sensor intrigues me in that for what I gathered from a 80's video on the motronic system the voltage is sent until 
a heater in the plug breaks contact (bi metallic switch) and or the heat from the coolant is sufficient. Therefore would only enrich the mix
if functioning properly.


The CO2 Potentiometer in my understanding (may not be real) is not "fed" any information re:exhaust gasses.
Though, I believe that it should be adjusted with the use of a gas analyzer, the CO2 Pot is not utilized to monitor any part of the system.
Mine is reading low according to Frank Warner's article from End to End should be 1K ohms, mine 750 ohms. 
The question is how or what information does the Motronics unit use to adjust fuel trim?


Surely someone has unearthed information regarding the mapping of a motronics unit.


anyone?
anyone?
Bueller...Bueller?

Canadakbike wrote:I adjusted the TPS to the voltage as described in post [url=http://www.kforum-tech.com/electrical/PDF/Motronic Fault Codes.pdf]Motronic fault codes[/url] moved to the tech page.


The water temperature sensor intrigues me in that for what I gathered from a 80's video on the motronic system the voltage is sent until 
a heater in the plug breaks contact (bi metallic switch) and or the heat from the coolant is sufficient. Therefore would only enrich the mix
if functioning properly.


The CO2 Potentiometer in my understanding (may not be real) is not "fed" any information re:exhaust gasses.
Though, I believe that it should be adjusted with the use of a gas analyzer, the CO2 Pot is not utilized to monitor any part of the system.
Mine is reading low according to Frank Warner's article from End to End should be 1K ohms, mine 750 ohms. 

First, Check the TPS by grounding pin #3 of the diagnostic plug with the ignition off.  Then turn on the ignition but don't start the engine.  The temperature light on the cluster should now be lit.  Open the throttle, as soon as it moves off idle, the temperature light should go out.  Close the throttle and it should go back on again.

Second, the CO2 pot provides an artificial lambda signal to the Motronic because there is no O2 sensor on the bike.  SInce it only makes tiny adjustments in the mixture and needs an exhaust analyzer to be set, leave it alone because it is said that if you run it off the end of the adjustment, it has to be replaced at significant expense.  Regarding the resistance, how do you know Frank Warner's resistance of 1k isn't high?

Third, the temperature sensor does not use a bimetallic contact with a heater, but is a negative coefficient thermocouple where the resistance goes down as the temperature goes up.  Obviously, a dirty connection either in the connector or between the threads of the sensor and the engine will result in a richer mixture.  These sensors seem to fail fairly often, as well as being prone to corroded electrical connections.

Thanks again for all of your input Point Seven Five.

Fortunately, Frank's righting on the subject is around as there is little more to go on. That been said, it's a baseline. May not be correct from factory but to have something to compare to is of some comfort.

Thanks for clarifying the water temp mechanism. As stated I was going off a you tube video from Bosch but who knows at what stage of development.

Might have time in the next few days to remove and do a hot water dunk to see if there is resistance change delta temp.

Thanks again, 


Jake

Canadakbike wrote:......

Might have time in the next few days to remove and do a hot water dunk to see if there is resistance change delta temp.

No need to do that. You can test the temp sensor at the Motronic plug on pins #21 & #32. You should get something around 2kΩ @20ºc and just 200 or 300Ω @ operating temp over 80ºc

My guess is that you have a problem with the temp sensor as suggested above. A dud sensor will give you an uncorrelated reading. Maybe corroded sensor connections or a short in the wiring to the Motronic. To rule out an earth short check both pins for continuity to earth. Corrosion will give you a higher reading well above 2kΩ.
Probably also a really good idea to clean and tighten all the earth connections, in particular the one on the spar under the tank. Sitting for a few years there's likely to be some corrosion which will create some resistance. The motronic needs a good earth connection to function properly. You can measure between pin #17 or #19 (I think) and the Neg battery terminal.

Try cleaning/re-seating the Motronic plug.

Its using a bit of oil. I wouldn't rule out the rings being a bit gummed up. Try running diesel engine oil and monitor the plugs. Check compression on all cylinders.

A long shot but check your timing plate is not a little retarded. That can produce an unclean burn. Timing can be simply set by eye.

I wouldn't use dielectric grease on connectors.

I see no mention of vacuum hoses or caps which perish and cause loss of vacuum to the Fuel Pressure Regulator. When this happens the injectors get fuel at full fuel pump pressure which is much more than what the injectors are designed for so increased consumption.

All plugs the same would have me looking outside the injectors simply because I would expect variations if it was a clogged injector issue whereas electrical or vacuum issue would more likely affect all of them equally.

Never fire up a K and leave it idling to warm up. Just ride off.

It’s my understanding that the vacuum line to the fuel pressure regulator only makes small changes to the fuel pressure to respond to changes in throttle and therefore vacuum. 

I think the fpr basic delivery pressure is set by its physical construction. 

If I’m mistaken, happy to be corrected. 

Failed vacuum hoses or caps would, however, allow unmetered air into the engine, meaning the air/fuel ratio would be wrong. 

Bill

Thanks to everyone that is pitching in to help figure this out.

I put some heat to the temp sensor and it is functioning as designed. 

To recap:
 
TPS                    Good
Water temp         Good
Air Temp.            Good
Hall effect           Good
CO2 Pot.             Good

Next on the list

Vacuum
Refurbish injectors
Balance throttle bodies
Fuel pressure test
New Plugs
Plug wires
new air filter
compression test

Warming up engine?

What is the thinking that K100's do not need to be warmed up?

I generally don't bother warming up any modern engine but wondering why specifically the K bikes.

Regards,

Jake

Canadakbike wrote:What is the thinking that K100's do not need to be warmed up?

My guess (I make no claim to be an expert on such things) is that the plugs don't get up to normal operating temperature as quickly if you just start the bike and let it idle.

Another thing you might consider is checking the valve clearances.

Engines of the past 35 years are built to tighter tolerances and don't require warming up to get things working properly.  Modern oils also lubricate better, especially at low engine temperatures.  Fuel injection also does a better job of providing a proper mixture than a choked carburetor so the engine runs better when cold. 

All of this is to increase fuel efficiency as expressed in miles per gallon, since an idling engine uses fuel but doesn't accomplish any movement.  Taking a plug reading after idling a cold(not at operating temperature) engine doesn't give good information because the insulator nose is not at the proper temperature(VERY IMPORTANT), and the fuel mixture is richer than at operating temperature.  This results in a reading that will be darker than it would be if the reading were taken properly.

The way I was told to do a reading was to do a full throttle run on a warmed up engine for a mile, and shut off the engine before stopping.  Then take a reading.  This was important on carbureted engines to check main jet sizing.  I'm not all that sure it tells much with modern fuel injection systems beyond identifying fuel pressure or injector operation.

A second reading is taken after a couple miles at highway speed, shutting off the engine again before stopping.  This is probably the most important reading because this is the operating mode your engine spends the vast majority of it's time in.  If your fuel efficiency and performance is good this reading tells you if the heat range of the plug is correct.

When the engine has been running for at least 15 minutes on the road, you can come to a stop, let the engine idle for about 2 minutes and shut it off to take the reading.  This will tell you how your idle mixture air is set.

Hey,

Awe with the gifts you all gave me for gifts for the holidays in the form of advice.

I'm back at it, a little uncomfortable due to chocolate and cheese.

So, over the holidays I spent a couple minutes messing with the injectors.
All were working nicely... as in;

holding pressure from supply side when closed
spraying a decent mist on discharge.

replaced filters, o-rings and caps.

Going to put the whole thing back together and see if I can borrow a gas analyzer.

Since I'm in the laboratory for the next few months (winter) anyone have any thoughts on a cheap exhaust vent for a garage?

Just open the door and man-up to the cold

I picked up two bouncy castle blowers for keeping bikes cool while tuning. I use just one for Bricks and two for cooling R bikes. They could be used as extractors with a bit of modification. First one cost me $6 Au and the second one I think was $8.00 Au at the local dump recycle yard. They are also good for blowing out the workshop. 
Happy New Year regards Martin. 

If you are trying to do the plug chop method, you have to be using new plugs. You don't read the tip but the porcelain area at the base of the plug. Anything off white there means the engine's air/fuel mixture is fine. You might have to use a magnifying glass and a light to see that area of the spark plug.

The types of modern fuel with ethanol and other additives, makes it really hard to get an accurate reading.

Just put my forth tank of gas in.

After all of the going over and checking the dodads for things, I opted to adjust the CO2 pot bit by bit. Last tank we went 300kms on 17litres 5.6liters/100kms not bad considering a third was “spirited” driving.

This isn’t over, still would like to get a gauge on the fuel system to ensure the fuel pressure is right and that the bypass valve is operating properly.

It’s entirely possible that there was something wrong and i’ve just masked the problem. I’ll let you know if I find it.

Even with "spirited riding the 16V K100 should get about 5L/100km. 

Have you checked the "zero" on the throttle position sensor?  The Motronic assumes an airflow based on throttle position.  An incorrect throttle sensor zero will result in the Motronic providing the wrong amount of fuel for optimum performance and economy.

See if you can get some Techron Concentrate Fuel System Cleaner and run half a bottle per tank for two tanks.  I don't know how long your bike was inactive, but it's possible there are varnish deposits in the fuel system, specifically the injectors. 

These deposits may be causing the pintle to be a little slow in closing, allowing a bit of overfueling.  The Techron can help clean them out. 

My first K100RS 16v sat for at least two years, probably a lot more.  It took a couple thousand miles to get the fuel efficiency and performance to where it should be.

I got bike 2 years ago with 17000kms so safe to say it was not used as a daily.

I had the injectors out cleaned, replaced rubber and hats. 
I have set the TPS to .375v. Measures Steady increase through throttle range.

The engine temp was fine but only measured at 20 deg C (winter in garage). Will check that now I’m free.

All motronic inputs were checked, and in range over the winter.

Did not check fuel pressure, that is where I’m left. Unfortunately, lockdown is making that a pain to acquire. May end up cobbling together a tester.

Does the fuel bypass work passively from the throttle vacuum?