hey,

I recently bought a K100LT `89, 88kkm- looks good, rides good, had all the liquids, filters and other things changed and i am only left with the valve clearance and injection synchronization.

what i started noticing is that when the engine is still cold or if the weather is cold, the engine tends to loose power (but not significantly) - it is felt especially around 3000-5000rpm and it feels like someone would pull me back or if i pushed the rear break from time to time. when the engine gets hot, the problem disappears, but not always.

i am thinking about:

fuel pump which is loud as hell
Injectors or the synchro
used cam chain

i also changed the filter on the pump and the CDI module as the one i had was a switzerland version limited to 45kW and 6500rpm. can this also be the problem?



i would be more than grateful for any clues;)
cheers from Poland
Marcel

hi marcel......hmmm temperature related ???

there could be a few things that may be affected by this ....but only 2 that i can think of where "temperature " is a direct reference .

1> there is a temperature sensor in the stub of the outlet pipe of the water return behind the radiator ....which is referenced in the fuel injection maping ..

2> there is a sensor in the (air flow meter) in the airbox , after the filter which is also referenced in the fuel injection maping .

it might be advise able to clean up the connections at the water sensor area (2 pin connector) as we have seen a number of issues with this in the past .

that sensor is a double ended one (two sensors with their center being the body of the water stubb)
one side of the sensor drives the fan control ......the other goes to the fuel injection .

not sure of the effects of the sensor in the air flow meter ...sorry

im sure there are many other temperature related things that i havent thought of ....but theres a start ....

by the way what do you concider cold ? dont mean to be ignorant ...but what temperatures are we talking about 5deg c ....10 ...15... ? we all have different comfort zones and what we might concider cold here (in queensland australia ) might be verry comfortable for you

but that noisy fuel pump, could well be an issue , especially at higher revs , where fuel flow maybe more a noticable issue .

note that there is on some models of k bikes , a noisy fuel return valve , and i do mean noisy ...the actuall noises vary and i wouldnt be surprised if it was that which you may be hearing


cheers

haha, well, cold meaning around 15C comparing to warm 25C. it was pretty chilly a couple of days ago and it seemed like the issue got worse even after the engine got hot. I'll check the water temp sensor - it is not the one on the water-oil pump? i have an LT and i am affraid it will be hard to get behind the radiator;) do you think it can be the CDI? when i changed it, it was pretty rusty and i forgot to clean it...

thanks for such quick reply!

no marcel .....giggles ...we all wish that the things on the outside were the easy way out .....the one near the pump supplies the signal for the indash meter .

it is under one of the side covers ....i think you will find it easyer to get at by removing the (drivers ) righthand side .....it is in a long way ...but there are many things to get in the way from the left hand side .

we recommend a product for cleaning up corrosion on electrical connections called deoxIT ...which many of us have found to be excelent .

if you get a chance it might be advised to clean every electrical connection that you come accross .....and yes that does mean the unit under the tank.......whilst there, do all you can

dont forget the computer under the seat as this is the fuel /injector control part

question? you did replace the intank fuel filter didnt you? .....whilst there make sure the fuel tank is spotless inside .

hey

i got to the connection behind the radiator but couldn't disconnect it :/ stupid question - is there a special way for those connectors to disconnect them?

yes i did change the fuel filter but i never actually cleaned the inside of the tank and as i opened the tank today to get some gas, there was water on the inside part of the fuel cap (or however you call it in english). that means that there might be some water in the tank. what is the best way to clean it? just take it off , shake and pour as much as i can through the top whole?

i'll try to fight with it tomorrow;)
cheers again!

i also forgot to add - i changed the spark plugs and 2 of them had white-blue-like dust on them which means that there was a short circuit between the wire cap and the spark plug (sorry, i do not know english workds for those parts but i hope it sounds clear enough). it looks like the wire caps (the ones which go on top of the spark plug) are not in the best shape... can you change them like you do on japanese bikes? just screw out and put a new, let's say NGK ones?

The spark plug caps and cables are one unit, if you change them they must have the same resistance or above the genuine ones.

If you use caps/cables with less resistance, you must use spark plugs with built in resistance (most makers add an R to the code number).

If the resistance is to low, you could damage your ignition ecu.

About the connector for the water temp. sensor, it`s a small wire clip you must press inn, while releasing the connector,

Inge K.

going back to that sensor behind the radiator? can this be the case? the problem is not big, the engine runs smoothly even when it's cold but somehow it just has power holes, it looses power, but it is not something what makes the ride hard or impossible - i can just feel it.

i think that it would be a really good idea to eliminate water in the system first paj ,......maybe some is restricting the flow through the fuel filter as that is where it gathers / collects as well as at the fuel pump body (roller cells dont like water there )
yes spark plugs and cables can restrict the smooth running ....the suggested plugs from ngk are d7ea ....but you need also to get the ferule (little aluminium bits that screw onto the top of them )

It wont hurt to check and clean this connector, but I don`t think it`s related to this as your problem also have got worse with hot engine.

I would have started with the two obvious things that you allready have mentioned, cleaning and checking the corroded spark plug caps and the connectors at the ignition ECU under tank which
you have changed.

Not that I think it`s related, but is the genuine exhaust still mounted.
The swiss model have a different silencer.

Inge K.

damn, really? do i need those aluminium things on the spark plugs? the last ones didn't have it and the new ones do not have it too! but is it possible to get that separately?

If you got the genuine spark plug caps these are needed for the connection.
They are usually not sold separately, but Bosch (X5DC) have the correct conector.
You should feel when the spark plug caps snap on to them.

This might be the reason for your problem, inspect and clean the connectors inside the spark plug caps.
A squirt of WD40 (or similar) inside aids mounting and protect against corrosion.

Inge K.

well, i just got the aluminium things and the spark plugs don't fit into the spark plug caps... without them, they go pretty deep, with them, a bit less and you cannot feel the "click". what do you think about that? the spark plug caps are genuine BMW ones.

Have you mounted the adapters correct, rounded end should point outwards.

Use a plier on the tongue on the spark plug cap, move and twist a bit so you feel that the caps are centered on the adaptors, then give it a firmly push to snap it on.

Inge K.

i tried it - it does not snap on. i took one spark plug off, put it in the spark plug cap withiut the thing first and it goes deep. then i put the aluminium thing on (good side out;)) and it goes less deep by maybe 4mm and even when i used pretty much force it didn't want to click on. what is going on?

Inspect the connectors inside the spark plug caps for damage.

Inge K.

This is how it should look on the inside, you see the small vertical wire inside the connector, this locks the connector to the adaptor.
[img]http://k100rt.aforumfree.com/[/img]
Inge K.

well, ok;) i wanted to say, i am sorry for arguing with people who probably know more about K100 than me, a pole about potatoes

secondly i wanted to say thank you as that had to be done - the previous owner (i got my brick a month ago) did not put those aluminium caps on the spark plugs and as a result, there were violent thunderstorms inside my spark plug caps what eroded them inside pretty seriously... what i did is i put the aluminium caps (got them for free from a car shop ), cleaned the caps with WD40 and a tiny screw driver and i put it all together - the clicking was "easily" felt end heard so who knows, maybe it will make a change. I haven't ridden it yet as i also cleaned the tank and need to get some gas first.

i'll let you guys know what was the outcome of that operation but it seems like i will probably need new wires sooner than later.

cheers!

good find marcel

i found a similar issue a month or two after getting mine ....and it did make a difference ....ever so slight...... but after a lot more riding was quite noticeable .

i would look at the water issue in the tank as well ....we have heard of corrosion forming and bad things

cleaned the tank - no water and just a bit of corrosion but definately not from the tank - it's aluminium;)

about the sparks - just took a ride around the block and it seems that it is better but still when it's cold you can feel a bit of that pulling thing. i couldn't disconnect the plug from that sensor behind the radioator because of that wire - is it really possible to do just with one hand and without taking the radiator off?

also i noticed that the fuel smell is pretty strong not only when i start it but also when i stop on lights and stuff- the smell comes definately from the air release on the right side of the tank - should i worry about it?

next thing is probably valve clearance and injection synchronization - i read in the manual that you can do it only with mercury meters, is that necessary? can't you do it with a regular one? sorry for so many questions, but i feel like i am almost done with working on it haha (naive)

thanks a bunch mates!

i am one handed at the moment so please excuse my lack of upper case.

if you want to get an idea of the wire clip on the temp sender the injectors have the same clip so you can practice on that. i notice you have an k1100 the clips are not the same as the k100. the 1100 will have a squeeze the wire and pull to remove but the 100 you will need a small pointed thing like a scribe or such to lift the clip and then you can pull it off. when you reconnect put the clip in place and push it on.

with regard to the metal surrounds on the plug caps i have never been a fan of them and replaced the ones on all my ks with normal silicon leads from an auto store and used a resistor type plug and have had no trouble in 5 years.

with other brands of bike mainly honda i found that the metal covers collected condensation when the bike was cold and caused missfires till they warmed up and mostly they were discarded with a big improvement in performance. they were so bad that most times i removed them at the predelivery service so the customer would not even know of their existence.
as for the water in the tank put some mythelated spirits in it and that will absorb the water. empty it out and refill with petrol.
check under the pump inside the tank as that is where the muck and water collects first and will cause corosion and eventually a hole. every k i have owned has had the hole and many others i have worked on. have a poke around with a probe like a screwdriver and make sure that is not where the petrol smell is comming from.

Like K Freak I am using bog standard 8mm silicon leads with non stud-type ends bought from the local parts store coupled with resistor sparkies (my choice is the slightly 'colder' for our hot climate, extended reach NGK DPR8EA), all with no problems for many many kilometres. I keep a selection of plug end 'nubbins' available when I change the spark plugs. My bike came to me second hand with the OEM leads and dielectric grease smeared all inside the lead's metal caps which seemed to keep corrosion at bay, though I hear tell a lot of this forum's members stay away from silicon dielectric grease in some areas of the bike.

KF, how'd that surgery go? You're still with us so that's a healthy sign.

thanks guys. K freak, i have a K100, not a K1100;) the tank is made of aluminium so it 's hard for me to imagine corrosion on that tank (?). but the smell is pretty intensive so i'll have to have a look at it soon.

cheers for help, even though you had to write so much text using just one hand haha

about the wires - yes, i'll change them but maybe next week, the K pumped out all the money for july;)

pajonk wrote:next thing is probably valve clearance and injection synchronization - i read in the manual that you can do it only with mercury meters, is that necessary? can't you do it with a regular one?

Anything made for this purpose can be used.


About the water temp. sensor connector, it`s the same connectors on the injectors (and TPS, but 3 pole).
Those ones are easier accesible for practising how to.

Inge K.

pajonk wrote:thanks guys. K freak, i have a K100, not a K1100;) the tank is made of aluminium so it 's hard for me to imagine corrosion on that tank (?). but the smell is pretty intensive so i'll have to have a look at it soon.

cheers for help, even though you had to write so much text using just one hand haha

about the wires - yes, i'll change them but maybe next week, the K pumped out all the money for july;)

Sorry I was looking at anothers persons profile while I was thinking and I am not at my best yet.

Aluminium will corode just as easily as steel and many other metals it just needs the right circumstances.

The K tanks are easily fixed with an epoxy patch, I have had total success on every tank I have mended.

so you think it may be a crack of some kind? does it mean that it shouldn't smell gas at all while driving, only during start?

pajonk wrote:so you think it may be a carck of some kind? does it mean that it shouldn't smell gas at all while driving, only during start?

Most likely a small hole under the fuel pump and you should not be able to smell fuel at all. Occasionally you may get a smell if the tank is very full and the bike is leaning over a long way on the side stand.
if there is a leak at that point you will most likely see it from the outside if you remove the lower left part of the fairing.

the smell definately comes from the right side, where the air release is. i'll take the tank off next week, i am off on a trip today, i hope i won't burn nah!

The right side is where the fuel overflow and water drain for the cap is. I think you will need to lift the tank to investigate it.

On the subject of fuel smell. Mine has been smelling more and more of fuel lately and I thought it was the lack of breather pipe that runs from the gauze filter on the pump to the pipe near the filler cap.
It wasn't. Puddle of petrol under the bike this morning on left side.
Pulled off the fairing panel and just where the pump is there is a bubble on the paint and a steady drip of petrol. Get out the epoxy putty.
If the tank corrodes at this point on the left side I would imagine there is a possibility that it could corrode at the same point on the right side too due to water collecting.
Breaking sweat at what the outcome of petrol could have been with fuel running over the cylinder head and exhaust headers.
Roast chestnuts anyone!

ouch john !!! .....lucky you investigated huh ? good luck with the repair .

I too had a leak but on the seam at the side, definitely caused by water sitting there, I fixed it with an external epoxy putty patch which is made for the purpose, 3 years on no more leaks.

With our bikes it is important to check that the rubber gasket under the fuel cap base is lined up with the drain hole beneath it is possible to put it on the other way so they don't line up, mine was wrong. Then every time you open the cap a little rain water drips in. Also with a metal tank when it is cold air that is drawn in when running and consuming fuel will be humid and will condense on the tank wall when cold and run down the tank wall. If there is water in the tank using a torch and looking through fuel it will look like mercury rolling around there.

If there has been water in the past the fuel filter will be affected and may be partly blocking the flow at high flow rates. So if you have not yet changed it it is well worth doing.

Well done for fixing the plug caps, I am not sure what year the resistor caps stopped in but the original K's had non resistor plugs and resistance in the plug caps as mentioned above the Bosch plugs were the R type. Certainly the 1990 had non resistor leads and uses R type plugs.

Well worth cleaning every electrical connection with DeoxIT.

I strongly suggest that you check for air leaks into the induction system, with our bikes leaks at the rubber joints between the intake manifold and the engine are common also on the various rubber bits you will find atached to the engine.

In chasing fuel smells which should definitely not be there consider replacing the fuel lines from the tank to the pressure regulator and the fuel rail with new fuel line if that has not been done, it perishes over 20+ years - mine had. Also if you opt to change the in tank rubber pipe you MUST use special fuel pipe not the same type as on the outside of the tank or it will fail. Easiest way is to get the genuine part from your BMW dealer.

Once you are sure all air leaks have been dealt with if the rough running is still there the air flow meter and temperature sensors would be the next candidates for a resistance check.
Regards,
K-BIKE

Comberjohn wrote:On the subject of fuel smell. Mine has been smelling more and more of fuel lately and I thought it was the lack of breather pipe that runs from the gauze filter on the pump to the pipe near the filler cap.
It wasn't. Puddle of petrol under the bike this morning on left side.
Pulled off the fairing panel and just where the pump is there is a bubble on the paint and a steady drip of petrol. Get out the epoxy putty.
If the tank corrodes at this point on the left side I would imagine there is a possibility that it could corrode at the same point on the right side too due to water collecting.
Breaking sweat at what the outcome of petrol could have been with fuel running over the cylinder head and exhaust headers.
Roast chestnuts anyone!

Not saying that a hole on the right is impossible but I have never seen one there. I reckon the fuel pump tends to draw any FOs to that side of the tank.

Seems to be the favourite side for a hole. Although another thread on fuel leaks mentions buying a K with both sides repaired using epoxy putty.
Rare, but not unheard of it seems.

haha, thanks a lot for all that help guys! i just got back from a 600 km trip on my BMW and well, i must say it was good;)

getting back to the smell - you can only feel the smell when the engine is running and when there's really little gas inside so i guess it may not be a hole.

second thing is that the power loosing thing...i think it's almost gone but i get that weird feeling that when it comes and i close and open suddenly the throttle it disappears - only when i open the throttle slowly it gets noticable - is it possible that that thing for throttle position (i don't know the english name for it - the black "box" at the end of the injectors) needs cleaning? or this thing is service-free?

third thing - is it normal that K100 has such a big and unfortunate power hole? between 4000-6500 rpm? mine has not much power in that range so when i had to overtake someone pretty fast i needed to go 2-3 gears down. the rest seemed ok.

i think that's it, no more questions!

gracias

TPS have only two switches, and senses two positions, fully open and completly closed throttle.

I see that your power hole have moved a bit up the scale........
Is the genuine exhaust still mounted, the swiss model have a different silencer.

Inge K.

the swiss version has a different silencer? damn those swiss... does it also limit the power?

Later K's had a resistive TPS and no microswitch so with later K's there is no click at any point in the throttle opening/closing sequence it is all done by electronics. They are able to get worn as is the air flow meter and a number of people who have suffered from problems due to that wear (diagnosed by measuring the resistance which should move in a smooth sweep without any sudden changes) have found cleaning up the tracks very carefully has fixed the problem. Caig Labs make a product called Fader F which I think I would try.
Regards,
K-BIKE

i have a clicking version as i can hear a click when opening the throttle so that means that it is service-free right? my K is 1989.

Not quite service free some people have had problems with water getting in and giving problems. But you do have the air flow sensor in the airbox which does have a resistive wiper. If you finally get to suspect that is a problem you can meter that over the full sweep and know if it is a problem.
Regards,
K-BIKE

got it, thanks

pajonk wrote:the swiss version has a different silencer? damn those swiss... does it also limit the power?

Have no idea about how much the difference it would be in real life. But I`ll guess that due to the more strictly swiss noise level laws, this silencer probably have a bit more restricted flow than an ordinary one.

Also with that in mind that the swiss models have less horsepower due to another ignition ECU,
I wouldn`t be surprised that both the ECU and the silencer together is the limiting factors.

The only way to find out is to try an ordinary silencer, since you allready have changed the ignition ECU.

Inge K.

ok guys, a little update on the case:

- I cleaned the tank - no water inside and it was pretty clean
- cleaned the connections (ECU and computer)

i went a bit further and investigated it more precisely and the results are:

it is not temperature dependent - it happens either when it's cold or hot (a bit more often when it's cold but it does not go away when the engine gets hot)

when the engine is cold, it often happens (but not always) that knocking can be heard (air leaks?)

today when i started the engine, i could hear knocking on idle (choke on) and the rpm were around 700. when the engine got a bit warmer (past the blue field) i turned off the choke, knocking disappeared but the rpm was still around 700 and the problem was easily felt (the power loss thing). then suddenly, while driving, the engine started working perfectly, it had full power and the rpm went up to 1000. and starting from this point it was once good, once bad. I noticed that sometimes when i accelerate (on any gear and speed) and suddenly close the throttle, the engine almost stalls (feels and sounds like i would turn off the ignition) reaches around 700rpm and immediately pulls back up to 1000rpm. it happened twice that it stalled completely while stopping.

another thing is that when it gets that weird "pulling backwards" like power loss, when i close and open the throttle immediately and pretty wide, it goes off nicely and when i do it fluently and slowly it does not.

one more thing is the fuel pump - there are days when it makes a horrible noise and there are days (like today ie) when it's pretty quiet (not dependent on the amount of fuel in the tank).


any ideas about that? I still Haven't checked the valve clearance and the chain tensioner.

can it also be fuel pressure? i have no possibility to check that but i should meet with a mechanic next week so i am looking for ideas what to check, not to loose too much money and time;)

cheers!

I can't see the cam chain or valve clearances having any effect at all but that fuel pump being eratic would certainly be worth investigating.
When the fuel pressure goes high it will run rich and low pressure will cause lean and a slightly lean engine will be a little hesitant.
Have you checked the vacuum tube from #4 throttle body that goes to the fuel pressure regulatot and also the crankcase breather which is just to the rear of the pressure regulator and partly under the air box (if it is leaking you get lean problems) and one other thing worth a look is the crankcase filler plug on the right engine cover as that can give problems if it is leaking.
The fuel pump certainly sounds suspicious.

knocking at idle is a sign that all is not well with the spark or injection.... having recently had the same issue mine turned out to be a bad spark lead and at speed it definatly feels as though an anchor on a heavy chain is draging behind slowing you up .

if it was fuel pump you would notice it at higher demands ...not really at idle as that is its lowest flow rate .

and yes the tank does make lots of noise ...and it sounds like the fuel pump ....but there is a fuel return valve that rattles like crazy on mine ...and i thought it was the pump ...

i suggest you borrow or get a multi meter and measure the leads to start with ...they should be in the range of 5000 ohms ...but some maybe less.
next check would be the ignition coils ...make sure they are bright and shiny contacts where the high tension leads connect to .....mesure with the multi meter between each high tension lead socket on the same coil ....it should be around 10,000 ohms , on both coils .

measure the primary of the coils they should measure 2.2ohms

of corse there is a distict posibility that the cables supplieing power to the injectors is also ..."fluffy" meaning a partly corroded connector somewhere ...

but the ignition / high tension checking is my best guess

good luck and report back what you find ..

yeah, i think all the signs on the sky point at the spark plug leads as mine are pretty corroded (the story with the aluminum caps on top of the spark plugs - mine were missing) and old - 22 years went by and the wires are still original.

now i just have to find a good subsitute for them and collect some money to buy them

i'll let you guys know what are the effects.

cheers

do the measurement first paj ....no need to spend money on things that "may be wrong " ..... what we are trying to do ...is confirm that this part is good ...this part is bad .....

you dont need to spend money until you confirm that this bit isnt right .

cheers

well, that is true i will, i need to get the meter first from my father;)

but, if the leads are bad (have a breakdown) will they show bad resistance? i guess they can get it while touching the cylinder head or vibrate - isn't there a risk that if i take them out to measure, they can show good resistance?

hmm ... good thought .....we are chasing something that is an intermittent fault ...(gets better then fails again )

but i think once you have the leads undone ....move them about to see if in fact there is a good / bad reading

i use alligator clip type leads for that sort of testing

It seems to me that one unit isn't always working. When it happens spray the exhaust with a plant sprayer and spray the exhhaust bents to see which one it is; there will be no steaming(better equiped people could use a heat gun).
As all the units get their fuel injected at the same time I would not expect a problem with the fuel system as it seems the other units are working OK??