Hi Kbikers! I'm introducing myself with this thread. My particulars will come out as I describe the issues encountered.

I bought an '85 K100RS that hadn't run in a couple years.



I signed up here to get some technical input so I could navigate its ills and have done well enough to get the bike started.

I replaced the fuel pump (having checked it first - defunct) with a Ford pump as described in a post here.



My apologies - I don't have the links now, I did most of this work a couple months ago.


Getting fuel to the rail, Mr. Injector-cleaned FIs, changing spark plugs, new battery - and cleaning the starter of carbon so that I have full spark brought me to the point where I could attempt a start of the bike.

A lot of oil past the rings - sat on side stand for who knows how long? Took about 10 minutes of running at idle to get it running clean. :pale:

As you'll see in the video, I can't get the bike off idle without a can of starter fluid. I did try this later with the intake funnel in place, but to no avail.



Having performed the electronics diagnostics, I am stumped. I think it might be the throttle position sensor, but it doesn't clean up when I detach the plug for that at the back of the fuel rail.

I've kept this description brief - thus leaving out things that you may ask if I've done. Fire away, I'll let you know - but I'm stumped by where to go next.

Thanks for the site!

hmm thats a tricky one nix ...

it would be good to open the tank and confirm that you infact have a good return of fuel back from the return line (thinking that maybe a fuel flow restriction through the fuel filter) whilst the engin is running .

a guess !.... could the connections to the maf (air flow sensor ) be corroded and its not seeing any change on throttle opening ? or even that it is frozen in place ?

have a look around the air cleaner area (bugger to get at properly ...but not too difficult )

after seeing the video you can see its trying to accelerate but dies ....hmmm ....

we have recently found the merits of a product called "deoxit" ...and it comes highly recomended .....available at all sorts of weird places ...electronics stores ...electric music stores and more ..absolutly great at cleaning up electrical connections

whilst your looking around ...undo and retighten connections to the computer (under the seat, efi stuff ) and under the tank (spark control)

or as i had found the 4 pin connector under the right side cover that feeds the fuel pump and in tank stuff, was intrermittent and would work for a few seconds at a time only ... that connection was fixed by crimping the female part of the connectors sockets to clamp around the pins tightly on reassembly

welcome aboard mate


hope your problems are little ones

Thanks for your welcome, Charlie!

I did check fuel return flow - it's good. I removed the in-tank fuel filter, bought a new one and fitted it outside the tank - just before the fuel rail so that I can replace it easily. :thumb

I cleaned connections when I was going through it and have gone through (I think!) the learning curve of getting the computer connections firmly seated.

As for the 4 pin connector - it's got a solid feel to it when it plugs in - unless one of the four females is loose and the other three snug.

Had the aircleaner out and cleaned a couple of times.

Question: Should I open the throttle position sensor and see if something is broken? I can't imagine that it will matter as I unplugged it and no change.

I'm a bit stumped because I think I've been through all the diagnostic pathways.

I will go through all connections once again - and reclean anything that doesn't look fresh and clean.

Again, thanks for the welcome.

hmmm if there was a short in the tps to earth maybe ....like full of water and corrosion .....

sheesh worth a look for only 2 phillips head screws

why not ?

but what i meant by the afm (air flow meter)...was the 4 or 5 wire connector to it, which happens to be in the top cover of the air cleaner ...

hope you find something and get her fired up and road tripping ..



crazy frog has a brilliant flow sheet in the technical section if you havent seen it

http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start.htm

cheers

I would suspect a severe air leak, I would spray brake cleaner around the intake tubes and would also check the crank case to air box tube. I had basically the same problem when I first got my K100(basket case) after I replaced all the intake tubes and the crank breather it was sorted out. I could spray brake cleaner around the intake tubes and it would rev until it burned off.

chrish8846 wrote:I would suspect a severe air leak, I would spray brake cleaner around the intake tubes and would also check the crank case to air box tube. I had basically the same problem when I first got my K100(basket case) after I replaced all the intake tubes and the crank breather it was sorted out. I could spray brake cleaner around the intake tubes and it would rev until it burned off.

:headbang

I think you may have just solved the problem. :nod

The intake tube was shot - fell apart when I tried to take it off - and I didn't even use a come-along, but gently pried it off the nipple. Came apart in my hands.

Well, I tried getting a piece of radiator hose with the right bend in it, but failed, so I said screw it, I'll just run it like that till I get a replacement.

I didn't think it would matter - but your post makes me think that I've compromised the feedback loop for air flow.



I will find where to get that and create a make-shift one today. More jury-rigging. :lol

As for the airflow meter - I'll pull the cover and take a look and do the same for the TPS. Cleaning never hurt anything. (mostly :suspect: )

I'll head over there this afternoon and take a look. :nod

most definatly ..... sounds like youve found it ...woohooo

Well, I had some success with this, but not a rideable bike.

Yet.

I made a crankcase vent tube and started the bike up. Worked ok - up to about 3000 rpm, but it faded out once again. After doing this for a while, I couldn't even get the bike to run.

I pulled the airflow meter, tested it again - electronically in order.

But a buddy stuck his finger in the port and tried to flip the airflow vane.

A terrible screeching ensued - and the thing moved. A little.

We pulled the unit apart, and found that the vane had "sunk" to the point of dragging as it swung.



We moved the shaft up a bit and filed the top side of the vane, put it together and the result is that it pivots freely.




I don't know if this will work in the long run, but it swings freely. When I reassembled the bike and using starting fluid, I could get it to rev up to 5k but not stay there. It would fade away.

I unplugged the TPS at the back of the fuel rail but that didn't change anything.

Oh, and I have about 2.5 or 3 gallons of fuel in the tank.

Now I think that maybe the fuel pump doesn't have the pressure?

I am stumped.

good work there nix ......i thought it had to be something in the air mix type sender..
just a thought ,,,you did confirm that the mate between the vane and the electronics fitted up properly ...and that return tension was noticed ie that the vane wants to close itself under some spring presure ???
you could test this with a multimeter (on resistance scale) accross the output of the afm and see if the value is varying as you move the vane .

yes quite possibly you could have a fuel presure problem as well


hmm how do you test such a thing ...i mean the easy way ....

maybe a thing you could try is to lean the bike over slightly towards the right hand side (whilst on centre stand )....with the tank open (maybe with the filler lid removed (4 screws)) see if when its running ..at more that 2000 revs if there is return fuel flowing out the return valve in the tank ...that in fact will confirn flow ....not nessecarily presure though

or in fact extend the return fuel line any old hose size might work for this test (above 6 mm ) and let it rest in the filler hole observing the flow..... i have noticed that the fuel pulses out the hose with the operation of the regualtor .


a sugestion ...to check the vacume line to the fuel regulator (picks off number 4 vacume inlet) on the throttle bodies and feeds the valve behind the plenum .
also check the little rubber hats on all the other vacume takeoffs

i suggest this, as you have found similar dead / cracked rubber on that crankcase breather ...

keep at it mate seems your getting closer

Thanks, Charlie! I hadn't thought through the cracked rubber bits - after I checked the boots and they were fine, I didn't consider the little bits.

As for fuel returning - I did a similar test - fuel returns ok, but I haven't tried it at 2000 rpm, so I'll give that a try as well. :thumb

I will check the vacuum line as well. I think I replaced that fuel line as well when I replaced the other lines.

As for the vane - didn't do an electrical test, just manual - it swings freely and the spring holds it in the closed position - but I didn't try to test resistance with a multimeter. I'll give that a go this afternoon as well.

I feel like I'm preciously close to making this thing run.



Now, where to get a new crankcase breather tube and fork seals?

I looked at a couple of the aftermarket resellers, but they mostly deal in used parts. I've not had good luck with BMW dealers in CA for old bikes. They'll make a calm man scream with misinformation, ordering wrong parts or saying they have it on the shelf when they don't.

Any help on that front would be appreciated.

Nixels, order from here if nothing else: http://shailsmotorcycles.com/

this is what they live for. He'll have it on the shelf most likely, and will ship. Vancouver BC Canada.

They've supplied me with the same parts for my 2 85 K's.

I'd be doing a fuel pressure check on the pump, make sure you have enough. The other thing I found on my RT was that the aluminum tubing in the bottom of the tank where the filter attaches was cracked and fuel pressure was escaping there. You can see it as a 'disturbance' in the gas in the tank, like a current. It gets more noticable with less gas covering it. You see it by looking into the tank while the bike is running.

Nixels, two really good US-based BMW dealers are Ride West BMW in Seattle and South Sound BMW just south in Fife, Washington. They actually stock parts for older bikes, know what breaks and what they should have on hand, and almost all of the people who work there ride their motorcycles everyday. They know what it's about and if they don't have they'll get it for you quickly. Ring Peter or Aaron in spare parts at SSBMW on 1-800-303-1838 and tell 'em Darren from OZ sent you.

Two Wheels Better wrote:Nixels, two really good US-based BMW dealers are Ride West BMW in Seattle and South Sound BMW just south in Fife, Washington. They actually stock parts for older bikes, know what breaks and what they should have on hand, and almost all of the people who work there ride their motorcycles everyday. They know what it's about and if they don't have they'll get it for you quickly. Ring Peter or Aaron in spare parts at SSBMW on 1-800-303-1838 and tell 'em Darren from OZ sent you.

:thumb

Peter says howdy! Much nicer and more informative than the Bay Area BMW dealers I've had to suffer through.



I hope to get back over there tomorrow - the work thing was demanding my attention these last two days - and I've been suffering a broken filling & impending root canal app't. as well. No fun!

More tomorrow !

I´ve had very good experience with ttp://www.maxbmwmotorcycles.com/ for general spares
For electrical parts http://www.euromotoelectrics.com is a good reference.
And if you have the OEM part number (not the BMW part number) always try http://www.rockauto.com/.
For example I found the HT coils at Rock auto by 118USD each.
Best regards
JAP

That worked for you then, good to know. Peter is a nut, a major motorcycle enthusiasts who always has an interesting 'bike project or three going. Aaron, the parts manager is another 'one of us' too. I'm glad to be able to help, Nixel. And good luck with that root canal. Cheers!

If you have to have a cap or crown after, the state of the art is ceramic crowns machined at the dentist and fitted on the spot. They are a lifetime solution.
Regards,
K-BIKE

Root canals suck!

My tooth is still sensitive two days later - granted not as bad before the doctor crawled into my mouth for two hours.



JAP & Darren - thanks for the links, etc. I'm sure I'll need some electrical part soon.

Yesterday I got new vacuum caps and hose because the caps were shot and the hose was brittle. No breaks in it, but I figured it wouldn't hurt to replace it.

It didn't hurt - but it didn't help either.

So today I'm going to go back and do the multimeter testing on the TPS.

I couldn't get the bike to rev and stay at 2,000rpm, so I couldn't do the poor man's fuel pressure test.

Any hints, I can check in on my phone.

club_c wrote:Nixels, order from here if nothing else: http://shailsmotorcycles.com/

this is what they live for. He'll have it on the shelf most likely, and will ship. Vancouver BC Canada.

They've supplied me with the same parts for my 2 85 K's.

I'd be doing a fuel pressure check on the pump, make sure you have enough. The other thing I found on my RT was that the aluminum tubing in the bottom of the tank where the filter attaches was cracked and fuel pressure was escaping there. You can see it as a 'disturbance' in the gas in the tank, like a current. It gets more noticable with less gas covering it. You see it by looking into the tank while the bike is running.

I missed this post earlier. Sorry.

I'll check that as well today when I'm doing my other tests.

Thanks for the hint.

I am still stumped - got a fuel pressure gauge and the pump tests at a rolling 32 - 36psi. It kinda bounces between those two states as the pump pulses.

I put in the factory breather tube - no change.

The bike has a hard time starting and staying on idle unless I give it some help with ether. It'll go a bit, then die. Ether will get it started, then after 2 or 3 times of this, it'll get up and stay at idle and that's about it.

I was going to do a vacuum test with the gauge, but couldn't find a link to follow.

I think I've done everything in the diagnostic that Bert has put together. I don't know what to try next.

How's the engine oil filler plug's rubber O-ring? Just a guess.

only other thing i can think of is if the timing is incorrect ......i think theres a check thread about adjusting the timing (advance or whatever ) in the forum somewhere ......
to me it kinda sounds like its way retarded

or just not getting fuel into the cylinders but that seems improbable now , as there is loss (pulsing of the fuel rail)


the timing is setup in the cover at the front right hand side ....front of motor, the same line as the crank shaft....about 4 allen scews i guess..

from memory theres a marker that should line up at about 3 oclock looking at it from the front .......have you got ..or can you borrow a timing light ....i guess the normal practice of picking off the no#1 cylinder applies ..

OK, your on route!!

The pulsing is from the injectors opening up, not from the pump. Depending how quick it is up to pressure again your fuel pressure regulator might be dirty/stuck or the pump's volume (at pressure) is not good. If you have the fuel pressure gauge connected and you close the return hose, does the pressure go above 36 PSI?

Have you already cleaned all the connectors, particularly the ground connections under the tank and on the gear box? These bikes use electrical resistances of various sensors to adjust the mixture. Any 'extra' resistance will have the ECU wrongly adjust the fuel amount and you have a rough running bike.

On the movie you were revving the bike quite a bit, have you had the fan and the temperature light come on already? You want to measure the resistance at the ECU connector between pin 10 and 13 as this is the signal from the cooling water temperature sensor.

As you have been running the bike with quite some oil in the cylinders, have you cleaned/replaced the plugs since? These bikes are very sensitive for dirty plugs.

Off course checking the valve clearance and a subsequent sychronising of the throttle bodies (after the brake cleaner test shows no air leaks) is a must.

Let us know how you get on.

Thanks, guys!

I'm headed over there in a little while and this is what I'm going to do:

1) Check rubber around oil filler cap (never did that)

2) Pinch return line on fuel rail and see what the fuel pressure gauge reads.

3) Check that ground and all connections are clean (I did do this, but early on so maybe I wasn't diligent enough?)

4) Check spark plugs (I've got another new set - these were replacements early in the exercise)

5) Check pins 10 & 13 for proper resistance.

The connections were in pretty good shape because the previous owner had tried to make this go and had cleaned contacts and tested resistance but didn't get as far as I have. However, a review of those connections seems in order and won't take long.

Perseverance may just pay off.

Nixels, the O-ring round the oil filler plug is the least of your worries, but have a look at it anyway as it is often the culprit in a poor idling engine and yours is not exhibiting this symptom. To test it simply get the bike idling and unscrew the plug a bit....the engine will stumble. It needs to be sealed tightly there. Good luck with the rest of your tests.

Sad day.

I've run out of money, time and - did I say money?

Going to part this out. There's a lot of good parts so people can fix their bikes.

I'll post up some stuff in the flea market.

Thanks for ya'lls help and interest.

If you have a want list, PM me.

Nicky

aww ....sad to hear nix ...pitty there wasnt someone close to you with experience in these things ....patience my friend is a vitue ....and when our pride and joy doesnt respond ....often we are left speachless ...as am i ..

good luck