Here I am again trying to sort out my idling problem. I have done everything by the book (books), got it idling at just under 1,000 rpm but when I go for a ride and it warms up a bit more the revs jump to nearly 2,000 and stay there. Very annoyed at this point. Can anyone come up with a reason for this? Throttle doesn.t stick, new cable, new vacuum hose, airbox secured correctly, valve clearances and throttle body sync. Only thing I haven't done is replace throttle body throat rubbers but they seem fine.
"Choke" cable idle gaps as per specs.  
Thanks RT

Hi there, I don't know the reason, but I've noticed that is related to the set-point of the air bypass screw at the MAF.
When it is properly adjusted, and the engine is tuned up, the idle´s hot increase is almost unnoticeable.
Hope this help.
Best regards

JAP

Adjust the thottle settings at operating temp not cold/warm, and see what happens.

Also, the RBike I have uses the same injection system and similar throttle bodies to the KBike except the throttle bodies are a lot bigger. It uses the BigBrassScrews to adjust sync at idle and to set idle speed. It then uses the throttle cables to adjust sync at revs (3K RPM). I'm guessing if you can't get idle speed right when it's hot then use the BigBrassScrews to reduce idle speed. Screwing them in should reduce idle speed so maybe screw them all in 1/4 to 1/2 turn and see what it's like.

But the bike should be at operating temp. You can point a pedestal fan at the radiator if your taking too long and the bikes fan is coming on.

All that said, this RBike idles at 2K RPM as one throttle body is worn and leaking air so that's where it wants to be to achieve sync, at least until the rebuild kit arrives.

japuentes wrote:Hi there, I don't know the reason, but I've noticed that is related to the set-point of the air bypass screw at the MAF.
When it is properly adjusted, and the engine is tuned up, the idle´s hot increase is almost unnoticeable.
Hope this help.
Best regards

JAP

+ 1 jap ....

bob you might have to open that grommet on top of the air box and wind the set screw (5mm)  a bit ...
there is a few posts on the old  lists for this

good luck mate

Yep ignore me, the rbikes have the same setup as 16v kbikes not 8v.

Here's a manual method of setting L-Jetronic K bike fuel injection CO (carbon monoxide) mixture
without the need for an exhuast gas analyzer:
1. Thoroughly warm the engine.
2. Remove the rubber plug from the top right corner of the air box, above the engine. Using a 5mm
allen, adjust the air flow meter idle air bypass screw under the plug for highest attainable idle
speed. This should be about 1-2 turns out from the fully-seated position CW.
3. Using a Carb Stix mercury manometer or vacuum gages, reset the butterfly bypass screws to
resynchronize and establish an idle of 1050 rpm, or about one tach needle width above 1000 rpm.
4. Now turn the idle air bypass screw CCW (from the top) until rpm is lowered by 50 rpm to 1000,
about 4-5 total turns out. (This is called the lean drop method of setting CO, if you don't have an
exhaust analyzer.)
If you live above 4000 ft elevation, be sure to install the high altitude compensating plug into the
harness. There's a receptacle taped to the frame on the left under the side panel.
As a final check, you know you have done it all correctly when:
1. You press the starter button with the engine running and the rpm stays the same or slightly
increases (enriching signal to the computer).
2. You pull out the high altitude plug and the rpm also increases (again, enrichening signal to the
computer, but less so than the starter. You've set it lean, so enrichening will increase rpm).
Don't forget to reinstall the rubber plug. I've also assumed you've got a 2 valve K with L-Jetronic
injection. Motronic works differently. Have fun!


This is how Rob Lentini went about it

i¨ve used this method , and it idles smoother than ever  

ungaas wrote:Here's a manual method of setting L-Jetronic K bike fuel injection CO (carbon monoxide) mixture
without the need for an exhuast gas analyzer:
1. Thoroughly warm the engine.
2. Remove the rubber plug from the top right corner of the air box, above the engine. Using a 5mm
allen, adjust the air flow meter idle air bypass screw under the plug for highest attainable idle
speed. This should be about 1-2 turns out from the fully-seated position CW.
3. Using a Carb Stix mercury manometer or vacuum gages, reset the butterfly bypass screws to
resynchronize and establish an idle of 1050 rpm, or about one tach needle width above 1000 rpm.
4. Now turn the idle air bypass screw CCW (from the top) until rpm is lowered by 50 rpm to 1000,
about 4-5 total turns out. (This is called the lean drop method of setting CO, if you don't have an
exhaust analyzer.)
If you live above 4000 ft elevation, be sure to install the high altitude compensating plug into the
harness. There's a receptacle taped to the frame on the left under the side panel.
As a final check, you know you have done it all correctly when:
1. You press the starter button with the engine running and the rpm stays the same or slightly
increases (enriching signal to the computer).
2. You pull out the high altitude plug and the rpm also increases (again, enrichening signal to the
computer, but less so than the starter. You've set it lean, so enrichening will increase rpm).
Don't forget to reinstall the rubber plug. I've also assumed you've got a 2 valve K with L-Jetronic
injection. Motronic works differently. Have fun!


This is how Rob Lentini went about it

Thanks for that everyone, I'll have a go at it. Been too hot for a ride anyway even at 800 metres here.
Looks a bit tricky for me but can only stuff it jup.
Cheers.

Also check that it isn't the TPS that prevents the full throttle return.

+1

Yes that was my hope, I removed the TPS and jiggled the arm but couldn't get anymore movement. It seems to me that there is something stopping the idle screw connection(spring and rotating disc thing) from coming all the way down. If I push a bit on the idle screw the idle decreases to normal, but winding out the actual screw still won't let the whole assembly drop down. I'm going to clean everything in there and hope I can find the answer easily. It always has idled a bit high but since I put in the new cable I cannot seem to get it right. Thanks for looking.

Have you backes off the adjustment on the throttle cable RT sounds to me like it is just too tight and holding them open a slight amount.

RT wrote:Yes that was my hope, I removed the TPS and jiggled the arm but couldn't get anymore movement. It seems to me that there is something stopping the idle screw connection(spring and rotating disc thing) from coming all the way down. If I push a bit on the idle screw the idle decreases to normal, but winding out the actual screw still won't let the whole assembly drop down.

Mine is the same RT. There is a few mm gap between the screw and the rest at the bottom. I can push it down and lower the revs but as soon s I accelerate it stays at the higher position.
Like that on both bikes.

Hi Rick, I must admit to having trouble adjusting the new cable , think I need a younger set of eyes on the screw as I move it. Could well be the culprit.
Hey Rossko, if it was only 1,200odd revs I could live with it but it's racing and November is aproaching and Putty road is calling and the temp will be hot and the road will have trucks and , well you all know what a panic merchant I am.
Trying to get time here as well, new puppy again, no sleep. Well not for me anyway.

Check your choke adjustment, if set incorrectly will keep the revs high, The first indent on the choke should lift the adjustment screw approx. 1,5 mm. 

RT wrote:Hi Rick, I must admit to having trouble adjusting the new cable , think I need a younger set of eyes on the screw as I move it. Could well be the culprit.
Hey Rossko, if it was only 1,200odd revs I could live with it but it's racing and November is aproaching and Putty road is calling and the temp will be hot and the road will have trucks and , well you all know what a panic merchant I am.
Trying to get time here as well, new puppy again, no sleep. Well not for me anyway.

You need Halo to come and give him a cuddle.
The throttle adjustment is done at the top end of the cable where the cable exits the master cylinder/switch block.
Where the cable goes in there is a conical rubber boot about 30mm long, if you pull that boot back down the cable the adjuster will be revealed and you will need 2 10mm spanners to unlock the adjuster then you can see how it will screw in to shorten the outer cable and let the throttle settle back to the stop.

Ok got that, found a slight problem.

I don't suppose anyone can see what the problem is here. I really must get my glasses checked.
Now that I fixed this little one, the idle has set itself at 1,500 steady so I can get on to the adjustments.

nearly fell off me chair bob ...! 
a marvellous find ol mate



to be honest those bypass screws look to be too far out also

Where else would you put your rubber knob while working on the bike?

Thinking about it, a lot of what has been suggested will not fix an idle that gets higher as the bike warms up. Maybe you got it.

I got shares in OPSM. Send them a thank you.

Hey Charlie, I set those screws using a man o man ometre, the readings were low, like 20 but all the same. When Waz did his they were around 42 odd, does that mean I should  do it again and wind em in all together?.

Ross, I had to go and check the other 2 old bikes to see how many vacuum holes there were and why I had an extra one. Took me about 20 minutes to realise what I'd done. Wasn't going to mention it but hey, I'm not absolutely flawless. (no correspondence entered into on that one).

Now I.m off to ring the dude with the 1100, if it idles well, I'll be trying for it.

im sure you got em matched bob

but as you say a bit low on the overall vacume reading 
I recon you could wind them all in a bit .... till you get about 500-600  revs ...then advance that idle screw down a touch so it touches the idle bar at least  to maintain that rev range  ..then do your adjustment ...you should get something like 23- 24 on the vacume reading right across ...it will probably come up a bit in revs as you do the adjustment ....I would be happy if you got  800 round abouts ...then turn the idle screw just a tweek to sit at 900 when warm

 the recommended  and often just right setting is about 1.5 turns out from being closed (fully wound in )
 
 just cleaned up a set of needle valves on my tbs ...you should have seen the gunk that came off them ..had to get a little 1200 wet and dry to make em shiny and not pitted with the residue that collected over the years

Thanks Charlie, maybe get on it tomorrow.
I won't be inside the T/B for some time yet, not game. But am getting a bit better with you guys behind me.

Well I have some better news, I followed Charlies instructions and seem to have a steady idle of about 1,000rpm, even after a warm run so I'll go with this for a while. Still have a sneaky suspicion that there might be a leaky throttle body rubber in there, but Hey, I can get out and ride again. (in fact I can't cause there is fire all around me, dang.)
Thanks heaps.
RT

wow ...nice news bob ...

see ....you can do anything ol mate

It never ends Charlie, as I had the bike up on the lifter I notived a bubble and wet patch on the tank bottom edge. GGrrrr. Anyway patched it yesterday with a Permatex metal tank kit ( I have a spare plastic tank kit here now, didn't have my glasses so if anyone wants a plastic tank repair kit, drop me a line).

Now I see that Throttle body top rubber no.4 is damp and dirty looking, better find that particular thread and get on with things.
Cheers

Ref the blanking rubber on the adjuster.
Thank goodness someone else besides me has done that!
Anyone else want to 'fess up?

I haven't done that one but many others that I aint gonna tell about. Well not till next time round the campfire telling tall tales.

More on this irksome problem for me. Cannot get any reaction from spraying carb cleaner around throttle bodies,
have cleaned out underneath the air adjuster screws (tks Charlie) and rebalanced the throttles still cannot get the revs down at idle when warm.

The latest test was to remove the oil filler cap whilst idling, and the revs dropped off considerably. As I can't ride around with this off, any ideas what this might be pointing towards?

Usually if an engine is getting runaway at idle the mixture is way too lean and letting the air through the oil filler is bringing it back down. This is so for carby engines but not sure if it applies to FI as well
I have never fiddled with this but there is an Idle air adjustment on the MAF sensor to regulate the air it lets through without the flap opening, Have you tried adjusting it.
I have a book here on the LE Jetronic injection by Bosch. It's in PDF so I can email a copy if you want one.

Usual disclaimers apply!

Thanks Rick I'd appreciate that. I've read Charlie's write up about that, looked tricky for me but I'm running out of options. I'll PM the email address thanks.

Another episode of war and peace.
I found a crack in the vacuum hose from plenum to crankcase and replaced it( had renewed it 2 years ago), thought that might be the prob , then noticed that No.4 injector was wet all around the top. This was after removing the plenum to check the T/B rubbers (all good).
Replaced injector, but do you think I can get the Plenum back on ( I have all the rubbers attached and need to slip them over the T/B bodies). 
Anyone have any tips for me, airbox is totally off so have good access just cannot get the fx88ng thing back on.
I'm off for a beer.

aw poor man bob

have you tried dishwashing liquid  with a bit of water around the top of the rubbers ?

the soap suds dry out leaving a good seal as well as being slippery to push the plenum back on ???

I'm with Charlie :-) bit of soap will work best. Then slowly rock it in from the right side of the bike.

Soap it will be then thanks. And as usual when working intimately with these machines, I found a small oil drip
out of that secret hole underneath the gearbox/crank join. AAAAAAAAAAAAAAAAAAAArgh. All I want to do is go for a ride.

RT wrote: I found a small oil drip out of that secret hole underneath the gearbox/crank join. AAAAAAAAAAAAAAAAAAAArgh. All I want to do is go for a ride.

Hey RT,
I don't want to invite myself to stay at your place, but I would like to invite myself to stay at your place.

Seems I have a secret hole also. And a drip.

How about we order a couple of rear seals and spend a weekend fixing both bikes.
We can both learn something new.

I will bring the scones.

Or we could just plug the secret hole  

You know, I though about just sealing that hole,  but eventually I would pay for it.
What a great idea, I want to change my final drive and lube the output shaft, take off the swing arm and do it properly so that would be a start. (did that once a few years ago and renewed the bearings so cool with that part).

Most welcome Rossckoe, do yu mind getting all the seals?, I'll handsomely re imburse you, just want to make sure I have all the right bits before I get that far into the gizzards.

You can kip down in the mother in laws digs, she has a king single, and it'll probably be cold.

P.S it was a bumper jam season here, so I'll have a choice for you, Blackberry Plum or Fig. (I'm guessing FIG).

RT wrote:P.S it was a bumper jam season here, so I'll have a choice for you, Blackberry Plum or Fig. (I'm guessing FIG).

FIGJAM   

I might head over for the day and clean parts for you blokes. I would like to see how it's done.

onya waz .... 

Seeing how half of Waz's workshop is in my tool chest at the moment that would be a good idea to come and conduct an audit.
Some good news here, I managed to get the plenum back on (rubbers upside down did not help),connected everything back up and she fired up first go. Need to go for a run and whack Waz's manometer on again to see if anything has changed, except that the weather has turned wet and cool.
Many thanks to all who chipped in, it helps to have the force with you when  faced with the BMW death star.

I might be getting somewhere at last with this problem. Gave full fairing on at moment so a bit hard to look at properly, but I sprayed carby cleaner where I could around T/Bs and found bubbles underneath the bottom rubber where it rests on the head. I guess the rubber is stuffed probably on all although No.4 has been my biggest problem to now.
 So my question now is, should I bite the bullet and order new rubbers, or can they have a sealing gasket
put in underneath. I understood there was a paperesque gasket in there originally? maybe not.
Think I read something about a gasket goo solution, these rubbers are really expensive.
Thanks guys.
RT

just some good petrol and heat resistant silicon type sealant should do the job bob ..

that bmw stuff  (verry expensive for quantity but amazingly economical for the amount required ) dreibond 1209  is good for this fix

you can get it from the bins at about half the price available here in aussie ....but put it in a combination order to spead out the freight costs

other wise there is suposed to be good alternatives in the "three bond " range ....remember the requirements  petrol and heat resistance ..

good luck mate ..it would be great to hear you have a good and steady idle at last ...under all conditions

Ta mate, not so bad in this cooler weather but need it fixed before the next trip up north in the hot climates.
Looks like I have the Go ahead to order new ones, from home office so need to pad the order out a bit more, new clips, 3 bond, seals, what else, before the bill arrives at the end of the month.

RT wrote:Ta mate, not so bad in this cooler weather but need it fixed before the next trip up north in the hot climates.
Looks like I have the Go ahead to order new ones, from home office so need to pad the order out a bit more, new clips, 3 bond, seals, what else, before the bill arrives at the end of the month.

dont think you need new rubbers bob ....

just reseal the bottoms to the head ...has worked for a few of us

might need some new oceter clamps though ....fortunatley they are cheap

you could use the old ones if you strech them apart with some expanding circlip pliers

just a heads up mate

Ta, was wondering that. Waz has a spare set he won't be using quickly so I thought I'd get it all undone and see if rubbers are ok first before I buy new ones. Got a 3 day quick trip tomorrow with Rickmeister, going to freeze ourselves through the Lachlan valley if it doesn't rain tooooo much.
Tks for tips mate.

I'm going in Ma.

Geez what have I done to my bike, hope I remember where it all goes.
Note the Dremel, an non OEM screwtopped bolt gave me lots of grief. So did using a grinder that close to
fuel residue, but got it out.
Now for the throttle body cleanup. Rubbers all look good, NO.4 was unevenly tightened and the sealing agent
wasn't contacting.
Time for my usual 2 days of procrastinating now before I get my hands dirty.   

Good find RT that should solve the mistery

Have my new Suzuki screw clamps, rubbers sealed back on, ready to attempt the re attachment of plenum etc.
Does anyone have a positive answer to whether it's easier to replace the throttle body/T/B rubbers and plenum
all in one piece, or throttle bodies first, then struggle the plenum back on?.
Thanks

Well none of that worked. Damn. This is really frustrating me. I have rebalanced the throttle bodies and still when it warmed up, straight up to 1,500 revs and sits there. When it has only just warmed up it sits on just under 1,000 rpm till it gets hot.
So I know I have good compression, new air filter, new and resealed T/B rubbers, and this time if I remove the oil filler cap with the engine running, it will drop the revs to just under 1,000. I'm guessing its not an air leak.

Next for me is to replace the Air flow meter with a spare and see what happens.
Any other ideas chaps??

Maybe if you re-polish the header pipes it might bring the idle down.

Or if you replace the rear main seal. I am sure I have one lying round somewhere I can send you