Hey Brick heads!

I'm chasing an engine running problem. on my 84 K100RS (2V)
Symptoms are:

Will idle nicely when first started (about 1100rpm from memory) but soon the idle drops to 950 (where I think it's meant to stay?) then she quits. It can be nursed along and kept running and it improves when it warms up, but I often have to keep it running with extra gas.

Occasionally the throttle off / idle speed will climb to about 2000, it doesn't stay that way,  it's not frequent, but definitely not uncommon.

Had a slight back fire for the first time the other day after reassembling post temp sensor check. This was with a handful of frustrated throttle though.

What has been done;

Crank Case breather hose replaced.
Checked Coils, seem OK
Water Temp sensor checks out.
Replaced Vacuum hose for FPR
Removed vacuum switch (2V models only)
replaced Fuel Pump
Fuel pressure seems OK.

Next?
So I wanna do the easy stuff first, like check that the throttle body rubbers aren't sucking air. ( is this done with LPG/propane released around the TBs whilst running?)
Next I guess test the air flow sensor (that gives me the willies, is it really as difficult as I imagine?)
I was gonna balance Throttles but I found out that valve clearances, timing and air leaks must all be addressed first, so those'll be next.

Anyone have a silver bullet I can fire into this thing?

I'll post some pics later as I know you all like to watch. I'm at work at the moment. It's looking a little different with an old new fairing kind of like a Frankenbeemer!

Jez

Checking for leaks is where I would be going next. LPG is OK to use, I use the carb and injector cleaner in a spray can.
Which coils have you got on there. Two types are, All grey and  black with orange towers. The grey ones are prone to failure with age far more so than the later orange tower type.

I Have the old (original type) coils, the tell tale white texta markings that would suggest that they've been replaced at some stage with second hand originals. They measure OK, but I think I read somewhere that the resistance measurement wasn't necessarily a dependable indication of dependability.

Jez 

The resistance needs to be right but you could have one layer of windings shorting to the next layer and the resistance still reading right or close (this is difficult to test for). Test for any connection from one of the towers to the laminated core of the coil and also from the primary to secondary coils. There should be no connection there not even on the megohms range, the meter should read OL which is over limit. Testing with a meter is not even reliable as you only use 9 volts and that may not break down the insulation and between layers it is quite possible to have 2000 volts.
I have a friend here that is an auto electrician and he lets me use the high voltage tester which will show up many faults that a meter wont see.
First see how the testing for air leaks goes. I try to test for the easy things first and often find that is where the problem was.
I have a Z1300 six Kawasaki and the first thing now is to put a new set of Dyna coils on them then see if they go ok. Not saying do it but as these machines age the high voltage electricla problems will become more and more common.

With the electronic ignitions that in use nowdays the voltages are very high in comparison to the old points style and even a slight leakage in the insulation very quickly breaks down and poof there goes a coil.

Hmmmm, might pay to do exactly that. Gettem down to the local Auto Sparky and gettem tested.
Jez

Quite often you will see them putting on a show after dark and spraying some water on them will kill the engine or make it worse.

Jez,
in my limited range of knowlege I would try to balance the TBs.
I used start ya bastard to test for air leaks and I had a doozy, but the SYB did not make a scrap of difference to the running.

What did show up when trying to balance the TBs was it was not possible to do it due to the air leak.

Only takes a minute to hook up the balance. If you can't get it close to right I would suggest air leak. If they balance pretty ok look elsewhere or maybe still a minor leak with secondary problem.

Ah Rossko, I saw a can of Start Ya Bastard not long ago, I nearly bought it coz it's such a great product name.

Wafted LPG all about the TB rubbers tonight, made no diff to the running, and after it settled in, the engine seemed to idle away without a problem. It seems for the moment to have healed it'self.     Oh yeah also the coils look oright in the dark, no sparks, so I think they're OK, haven't tried spraying water.

So I finished bolting on the new old top half of the fairing to get it ready for pink slip inspection on Sat morn. AAaaaargh,  the front brakelight switch ain't working!

Rear brake switch activates light. Front switch tested good as does the first length of cable down to the plug under the tank (I don't even swear anymore when I have to take the tank off) but as for tracing the wire and checking the wiring diagram on the trouble shooting PDF (my eyes are only just beginning to uncross themselves)  I'm just not sure where to check next. The bulb detector unit? further down the line?
Does any one know does the front brake circuit earth in a different place to the rear? Ive got tomorrow night and early Sat morn to sort this or have to put off rego check until I sort it.  

Not happy Jez.

Mate, drop it off, say you will be back in an hour and pick it up with pink slip in hand.

I have had two blue slips done on my bike.

Both times it was as near perfect as it could be.

Both times I came back and the bike was exactly as I left it.

They don't know how to use the lights n shit.
they look at the tyres. squeeze the levers and declare it road worthy.

Don't be there to show them how it works.

But if I was you I would fix those lights

On Sunday

Jez wrote:
Does any one know does the front brake circuit earth in a different place to the rear?

Does your bike have the earth wire from the right handlebar control unit to the main earth? (I don't know at what point BMW added the earth wire).

If not, just try earthing it to see if that helps.

I know it sounds real obvious but check the fuses by swapping them around...sometimes they look fine but are not. Sometimes or should I say most times the electrical connections become dubious so disconnect every connection you can see lube and put back together.
does the brake red brake warning light stay on when you select front brake after the rear of course?...I have replaced both front and rear micro ( which are the same part number ).....good luck you will find it but it may be on Sunday as suggested already.

Klompy the grey brick wrote:I know it sounds real obvious but check the fuses by swapping them around.

Yeah but yeah but yeah. Doesn't the fuse service the circuit without favour to either switch?
Can it be the fuse? if the rear brake is switching on the brake light?

I'm goin to bed any hoo, s'posed to up at five.

Jez
 

such an easy thing to check and then go deeper....although it does point towards the front micro or whatever it leads to....you will win Jezza she is just playing with you....

The brake light switches do not have an earth associated with them. There is a Green/black wire to feed power and they switch that power to the BMU via a Red/grey front E1on the BMU and a green/grey rear E2 at BMU

which one Rick?

just to add something different to the mix about the idling

there is a bypass screw on the maf unit (inside the air cleaner box )

could this be wound right in so its closed ? and now affecting the metering at idle ?

I guess some folks could go haywire trying to solve high idle  problems and inadvertantly wind this widdle thing all the way home....with little effect to the high idle issue ...but will stuff up any regular type of idle if they do all the other stuff and get it right at some time after solving the throttle body settings .

turn that screw ( 5mm allen screw)  out a bit (anti clockwise )  unfortunately is sits under a rubber grommet in the top section of the airbox

just as a heads up ...worth pulling out the throttle body bypass screws - jets and cleaning them up also I have found a few completely blocked with blowback, oily substances and crap to the stage of being almost completely blocked ...carbi clean does a good job ...but get pipe cleaners to really get in there and remove the crap (bit tricky getting to the feed holes as it right angles away from the jets in the throttle bodies ....but sometimes the carbi clean gets in there and opens it up without taking off the rubbers on the top side ....give it time to work and dissolve the gum ..then  blast it again ...make sure you use a tube on the pressure pack to get the blast down in the holes properly

just a thought that might help

Klompy the grey brick wrote:.you will win Jezza she is just playing with you....

Ya think 23 years (doh! anniversary in a couple of days 24 coming up!) of marriage would steel me to these games.

 :cyclops: 

Got up nice 'n' early this morning, and after missing the post that Rick put on this thread altogether, took an hour of poking around and looking at circuit diagrams, and yes as Rick suggested, the problem was indeed at the BCU. I have temporarily bridged the back brake switch and front brake switch here and had both working of the RBSwitch connection at the BCU.

Do these tend to be readily available as a 2nd handy? Anyone got an extra?

So after about a five minute inspection, hooray pink slip. I celebration (and now we don't have to have a rego sticka in NSW) I have added my own new sticka, I loved it so much I think I'll make it my avatar.

 
The bike is looking a little ugly (duckling) at the moment, but as I know you all like to watch so......





So next it's off to the fuel intake, Good advice Charlie, about cleaning up the throttle airways. I will, as I have with rest of the bike noodle on through and should have it finished about this time next decade. But it'll be fun any way.

Thanks for the help again,

Jez.

OK, here's the latest in the saga of getting the K right.

I had the Airbox off again today, checked the air temp element. That seemed to be OK. checked the airflow meter, that seemed OK. So off to the throttle bodies and thoughts of a clean up.

Removed the plenum breaking the OEM clamps (is there a hose clamp that fits these without having to get new clamps and BMW tool 653Z-2.1/el/a-BZK ?) Fuel rail removed. Injectors out, looking very scuzzy. throttle bodies, ... off. down to the mounting rubbers. cut some polypropelyne covers for the inlet ports. and while fitting the last one (cyl #1) I noticed this!



Is this evidence of dodgy rings? on second glance, I'm hoping that it's just been sucking filth from the engine surface through a broken seal around the leading edge of the throttle body rubber.

Any ideas?

Jez.
 :suspect:

certainly looks like oil

but I wonder if its actually a leaky injector flooding the inlet path ? and blowing some carbony crap back up the inlet path ??

in any case looks as though the seal between the bottom rubbers and the head may have been leaking a little . (pretty common from what I have seen )

Jez, looks like mine after an air leak on #1

Closest to the oil thingy from the engine bit that lets gas come out with maybe a bit of oil to make things look worse than possibly they should.

Maybe Blakey can come in here to explain it those who don't understand the correct terminology or the full complexities of the internal combustion engine.

Jez, do you need a visit?

Got a few days off this week and lots of opinions to share.

Thanks Rossko, you are welcome to pop over anytime you care to, I'm off all week with possible exception of friday.
Jez.

PS besides, I might need you to point out the "oily thingy" to me.

"Maybe Blakey can come in here to explain it those who don't understand the correct terminology or the full complexities of the internal combustion engine."

Suck

Stuff

Explode

Blow

repeat...

I did not include a diagram, so try and keep up rossko.  

omg ...funny as !@!

suck squeeze bang blow the principle of the OTTO cycle as well as just about every internal combustion engine as well as jet engines both axial flow compressor and centrifugal compressor......some refining occurs in the K100....


with diagram for Rossko.....

Temperature-Entropy diagram
The idealized diagrams of a four-stroke Otto cycle Both diagrams:
the  intake (A)  stroke is performed by an isobaricexpansion, followed by an adiabatic  compression (B) stroke. Through the combustion of fuel, heat is added in anisochoric process, followed by an adiabatic expansion process, characterizing the  power (C)  stroke. The cycle is closed by the  exhaust (D)  stroke, characterized by isochoric cooling and isentropic compression processes.

Update on the progress.

Thanks to the flying squad of Rossko and Klompy for their visit the other week, my mental information cache was filled about half way through their visit, so the rest of what they said, pretty much spilled out the other ear and I fought of my glazed look and fed them with coffee and scones while I digested what I could.

I have removed the air intake box, radiator, plenum, TBs and injectors. while it was off, gave everything a good clean. Carby cleaner is my new friend. I didn't take any pics of the stripped down engine but you can get an idea from Klompy's Avalon visit post HERE.

Got to it yesterday. It was another warm one in Sydney.


After everything was nice and clean, started the rebuild swearing to take more bloody photos next time I pull something apart!

The Inlet pathways weren't as grubby as I though after having a look down the guts and being a little  more filthy around the upper area.
This is number 1.....

This is number 2.....

This is number... DOH!

After looking at these photos up close now, I'm a bit concerned about the detritus I've left down there, so any old (or new) mechanics can advise me on the ramifications of leaving that s**t in there. (too gritty? or will it burn out?). If I do need to go back in there, how would you get it clean without taking the head off?

The TBs are clean enough now to eat from (as long as you don't mind the Carby Cleaner after taste, I find that the cheaper ones offend my palate)the rubber and mounts all look good.
I've put a little silicone gasket goo under the stub mounts. I did this for heat not even thinking about the fuel and silicone consequences, If everything works as it should though it won't be in contact with fuel.

So by late arvo I had it all back together getting more excited as I crawled towards getting the tank back on.

Got it all back together just before dark last night, last thing connect fuel line to fuel rail........ :suspect:
fuel leak. dribbling from fuel rail to injector joints ( didn't really check if it was just one or many)


I'm feeling I'm missing something here. Klompy has very kindly loaned me some injectors and I've sorted through and picked the best looking O rings to use. I broke a clip when removing the injectors. With the injectors, the Klompmeister has given me another clip, I think it might be from the donor vehicle (Hyundai) as it's a different size.
So... does the clip provide any pressure between the injector and the rail? Or is it just there to hold everything in place during assembly?
I assumed the later, and put it back together without it. The amount of fuel pissing everywhere suggested to me that there wasn't much holding it in. (This was without fuel pressure being delivered!)
So I'll have another shot today, get it apart, clean and oil the O rings , check the fuel rail for shite etc an have another go.
I will order some new O rings and injector clips. But I feel like I don't have anywhere near enough pressure the moment between the rail and the injectors, could be an assembly error.

 
Jez

Why was that hexagonal thing in the port?

It's my allen key socket drive thingy, it fell off my drive as I reached over to tighten the first throttle stub. 

Could have been bad, I had a very high quality 8mm ring open end spanner go down the fuel injection ram tube on my dragster once and cost me an engine in about 3 seconds. It went straight past the butterfly and almost past the valve.

Hmm got the leaks still, may have to have another go.
Got new O rings,
Head clean, Fuel rail clean, O rings oiled.

Mental note, DON"T USE SILICON GASKET GOO AROUND FUEL!



Each job seems to make the engine run a little better. She's still cantankerous when cold but I'm surprised how much smoother the engine is now, It didn't feel that rough before, but in comparison, she just runs a little more....... I dunno, smooth.

Next I suppose will be the valve clearances, so further tuning can be depended on.

Jez

 

Those can be a problem to seal at times I use the carby and injector cleaner and make the O-ring seats super clean and then use vaseline on the O-rings then put them in the rail and clip them in and put all 4 in the holes in the head and holding the rail work the lot round and round and they slowly go down.  If you just push them in you take the risk of damaging the O-ring.

Well I've been busy doing all sorts of K-irrelevant stuff of late, but I have the bike back together and commuting presently.
A last reference from the forum before ordering tyres has seen me with a set of Pirelli Sports Demons. Funnily enough a recommendation from one of the UK boys was the last thing I read (don't listen to the Oz riders, an something about riding in wet conditions) just as well, it's been nothing but wet here since I had them fitted.
Hats of to those who ride in the continually moister parts of the world.

I sourced the original RS bars when I replaced the clutch and throttle cables, partly out of laziness ( I knew all the lengths would be right) and partly out of wanting the dash panel to fit properly and also to return to some originality (though colour scheme will eventually change and I think I'll keep the bottom panels of fairing off).

So I took it for a long ride about 10 days ago, Avalon to Milton and home. I'm really wondering about the choice of bars now. My back is still killing me.

Some road porn for those who like pictures......


So anyway, bike runs OK...... when it warms up. I did notice though when you start it up in the dark that the alt. light glows faintly for a good 10mins (just a faint pair of snake eyes in the dark recesses of that side of the dial, the lights are out on the right side of the cluster).

It's incredible how much smoother the engine runs with ear plugs in as well. I'm guessing the timing chain and tensioner might need  replacing soon.

Anyhow she's up and going for now, smoother than before but more to fix

Jez.

 -o:

Lovely backdrop for that photo!   

good to hear jez

the demons are a great tyre mate

Jez wrote:Well I've been busy doing all sorts of K-irrelevant stuff of late, but I have the bike back together and commuting presently.
A last reference from the forum before ordering tyres has seen me with a set of Pirelli Sports Demons. Funnily enough a recommendation from one of the UK boys was the last thing I read (don't listen to the Oz riders, an something about riding in wet conditions) just as well, it's been nothing but wet here since I had them fitted.
Hats of to those who ride in the continually moister parts of the world.

I sourced the original RS bars when I replaced the clutch and throttle cables, partly out of laziness ( I knew all the lengths would be right) and partly out of wanting the dash panel to fit properly and also to return to some originality (though colour scheme will eventually change and I think I'll keep the bottom panels of fairing off).

So I took it for a long ride about 10 days ago, Avalon to Milton and home. I'm really wondering about the choice of bars now. My back is still killing me.

Some road porn for those who like pictures......


So anyway, bike runs OK...... when it warms up. I did notice though when you start it up in the dark that the alt. light glows faintly for a good 10mins (just a faint pair of snake eyes in the dark recesses of that side of the dial, the lights are out on the right side of the cluster).

It's incredible how much smoother the engine runs with ear plugs in as well. I'm guessing the timing chain and tensioner might need  replacing soon.

Anyhow she's up and going for now, smoother than before but more to fix

Jez.

 -o:

Lovely pic Jez. The last few times Ive done that ride its been so darn busy that getting a shot like that would be impossible. 

Im going to be heading out to my cache of parts pretty soon, so if you need anything let me know. 

Were they LT/RT bars you had on there before you got the RS ones or aftermarket ones? Im really enjoying the LT bars on the RS fairing. Im an old fart in a 30y.o. body and waaaay prefer the upright position to the lower RS position. Although as far as 'sporty' positions go, the RS is fairly mild. I have broken my left wrist 3 times and really hate having my weight pushing down through my wrists. 

Looking forward to a ride day (that I am available for) for all us Sydney siders.

In the most recent bit of work (apart from swapping over my old airflo unit for yours) was to renew the throttle and clutch cables (I was developing a hulk like left arm such was the strength needed to actuate the clutch) I bought the original RS bars so I was sure of the cable lengths, you can see in earlier piccys of the bike, I had a bastardized bar.
After riding though, especially the day I took that photo (8.5 hrs in the saddle) my back was killing me. I gotta say I've been coveting Bob's set up. I like Bemade's bars as well. The guy from NZ who did the cruiser thing.https://www.k100-forum.com/t5107p200-89-k100lt-k100-custom-conversion

Jez.

Hi Guys,
Been away from the K for a while for a few different reasons, but i have been doing some thinking.
Ive been having problems getting a smooth running engine since I bought it.
I need to balance the carbs,
but first I need to check the valve clearances,
But first I need to check the timing chain,
But before that.....  It seems that cyclinder 2 & 3 are showing about half the compression of 1 & 4. I immediately assumed that it was the rings, but I read somewhere in passing here, that low compression in adjacent cylinders is a symptom of a blown head gasket . ( It was one thing I did check when I bought the machine, check for oil scum in the coolant.... none present) I never even thought about a gasket going without coolant interruption.
I haven't been out on her for a couple of months due to lack of maintenance time, interrupted by work stuff and then a holiday surfing the Indonesian Archipelago (Woooooo!)
When I got off her I she was acting as if she'd had a mild stroke. ie indicators turning into hazards and swapping over etc. Starter not responding sporadically, headlamp intermittent, This I believe is a symptom of shagged starter brushes (?) (and or a dodgy fuse #7, check out and seems OK)
So I guess this weekend, I'll remove all associated bits and see what I should bother "The Bins" for.
Any thoughts on the compression situation?

Jez

Do a simple leakdown test by putting compressed air into #2 and see if it comes out #3. Have #2 at TDC with the valves closed and the valves on #3 will be on overlap so air would come out the ports 20° BTDC will make it come out the exhaust port and vise versa

Thanks Rick,
Job number 1 for next weekend.

good luck jez

and welcome back !

hope your issues are small ones

I had similar issues..
Please check your battery...make certain it's in excellent condition...
My bikes was displaying all sorts of weird symptoms...instrument gauges flickering, engine backfires, etc...
I replaced the battery......
Problem solved!

Hope this helps..
Cheers
Gabriel

Changed the brushes in the starter motor on weekend, this seems to have cured the schizo behaviour of the lights and indicators.
Noob mechanics note: Read the manual BEFORE removing parts and disassembling. I managed to get the starter to run backwards on the first attempt at reinstalling.
Back on the road and commuting today, just in time now that the school hols are over in NSW, traffic status now returned to "shite".

Jez

Started blowing air down the cylinders over the weekend. Hmm yep leakage. thought I'd look at the valve clearances while there........ what valve clearances! I didn't have a feeler slim enough to fit between any of the clearances.
So I'm guessing I'll take the head off and have a shop redo the valves and clearances. I don't think I have the wherewithal to take this task on. I'll take the head off next weekend, and check the valves.
I don't know what to expect, but I suppose depending on the state of these (burnt cracked or good) I'll either have them reconditioned and the head rebuilt, or try and buy another head or donk.

 

The good news..... 6 rivet shaft looks good.

Just do the shims to start with. Don't do the head unless necessary, it's a good chance it is only shims at present.

I got caught years ago with my K100 when I first got it and when I took the head off there was nothing wrong except that the shims needed changing because they had closed up over the last 100K. When I asked the PO when was the last tine you did the shims he replied "the what"

Ha,
I probably would've asked the same question!

I gotta get the right size shims obviously, but how to calculate the shim sizes needed is at the moment a mystery, given that I have no measurement of how tight they are as the clearance (if there is any) is so small tat I can't presently measure.
I see that The Bins have a kit, but for all I know I'll use up all the 1 size.