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  

RT I have a feeing that it's a bit lean at idle and starting to get runaway. what i would suggest is to make sure the throttle butterflys are closed totally at idle and more important that they are all set at the same position (equalized) then set the idle screws by vacuum readings.
I have used a 1.5mm drill bit reverse end to get the gap under the butterflys to set them and Floyd did the same recently.
There has been lots of posts here about dont touch the linkages between TBs but if they are out of sync then they need to be done so check them first ans see if one or two are a bit out. That will give you lean burn runaway at idle.

Thanks mate will give it a go. Package arrived today, all good tks.

When you take the TBs off hold them up to the light and you should see just the faintest bit of light past the top and bottom of the butterflys. Also check that the shafts are not worn by getting a finger in each side and test for movement, that movement is what often causes the things to get out of sync because the butterfly will move sideways instead of opening when the pressure from the cable or adjacent TB is applied

What an absorbing tale, RT.  It reminds me of my experiences when I took the first steps towards bonding with my '85 K100RS.  I too wrestled for the longest time with refitting the airbox thing. In the end, I found I was trying to put the TB rubber connectors on upside down.  There can't be more than a mm or two difference in the id of the ends, but it sure makes a huge difference when you do it properly.  I found with a smear of silicone grease the little buggers realized resistance was futile and the whole assembly slipped into place without further drama.  What a relief that was!
It was a frustrating experience, but she's become a wonderful traveling partner now.  I'm fortunate to have nearby a good many fine roads where her high speeds capabilities shine!
Don't give up, you'll get her sorted   
If you're using worm drive hose claps on the rubber bits, be careful how you orient the screws as it's all too easy to foul the arm that operates the butterflies via the throttle cable.

Got any plans on sad'dy or sund'y?

Bit of blue thunder workshop day?

Seems I have a free weekend.  Wife is off to Arnhem land to eat grubs for a week.

Would save on postage to get that seal down to you

I was thinking of popping down to see Waz also. Haven't told him yet.

Two birds...

Thanks brickrider, it took me ages to align the clamps but I managed. The frustrating thing for me is that the bike runs beautifully, I've done 20,000 miles on her with this problem so it doesn't seem to affect the running except it helps her overheat in slow riding traffic. Makes me scared to go and visit the northern guys here in Summer.
Now it looks like I'll be taking the T/B assembly off again.

When I put everything back together this last time, it was the first time that I truly expected her to start up
when I pushed the button. Must be getting better at remembering where it all goes.
Cheers RT

Rossskkko, always a pleasure. You are welcome to come and help me clean out the shed, have a bonfire, drink beer and look at me bike.

(How many K's in Roscoe anyway).

You say it seems to help it overheat a bit, that is a symptom of running lean. If you leave it idling when hot I bet the headers start to glow red hot.

Anytime Rosko, I have your seat here too.

sad to hear bob ...

I have seen  a few throttle bodies now and many seem to be out of sync  ...what I see, is some have movement in the linkages ...as you get further away from the cable assembly it seems that the linkages take up a bit later than the ones inside and closest to the centre  and so the butterflys hang open more on the inside and more closed on the outside .

could it be that the adjustments during idle with the gauges are disguising or hiding the fact that the centre butterflys are open just a little bit more than ...erm normal  

old gerty is quite happy to idle at about 6 or 7 hundred ...and very consistently at that after a tweek up at albys place .

good luck ol mate  you will get to the bottom of it im sure ...especially with all those local and good willing mates

The air bypass adjusting screw at the AFM have been mentioned a couple of times allready.
Have you tried to close the screw a tad (~1/8 - 1/4 turn)?

No Inge I haven't, thought I'd do the hard stuff first because I'm an idiot. I did have a leaky rubber though so just as well. I will try that now as I'm getting desperate, and it's warming up here a bit, good riding weather.
Tks mate.

Been a long story, hope you got it sorted soon.  

I don't fully understand this. You are to adjust the bike when its warmed up, so how can you have a raised idle when the bike is warmed up? It seems you didn't do your synchronizing/idle adjust with a warm bike? When the bike is warm close your brass bypass screws equally until idle is as it should be I would say. (if you know certain you don't have any air leaks or the engine is running too lean).

Hi Renez
what happens is, I start her up with "Choke", put my gear on, get the gate open etc by which time she is purring at just under 1,000 rpm. I go for a ride, say 1/2 hour, by the time I get back she runs at 1,500. Has done since I had her. Now that I have eliminated air leak possibilities, I though it would be better.
So in using a manometer, engine hot, and idling at 1,500, I set the screws. Let it cool down, start up, 1,000 rpm. Gets hot, 1,500 rpm.
See my problem, I used to have hair ( well some anyway) but it's rapidly disappearing. As I said, it'll run all day
without a problem but if I get caught in traffic or hot day, she doesn't like being still and the fan works overtime.

Any input is welcome, thanks.

Hi there, once you arrive from the ride, low the idle using the butterfly's adjustment screw, not the TB´s or MAF air bypass, check and adjust the TPS if necessary.
Now when you start the bike the cool idle will be low, adjust it by the "choke" until reaching the working temp and normal idle with no choke.
That´s what I do.
Hope this helps
Best regards
JAP

Thanks JAP, I'll give that a go. Going to be really cold here next few days so the bike won't get hot. Ha.
Cheers mate.

japuentes wrote:Hi there, once you arrive from the ride, low the idle using the butterfly's adjustment screw, not the TB´s or MAF air bypass, check and adjust the TPS if necessary.
Now when you start the bike the cool idle will be low, adjust it by the "choke" until reaching the working temp and normal idle with no choke.
That´s what I do.
Hope this helps
Best regards
JAP

yep same here jap

How far are your bypass screws turned out? Again, idle should be set with a warm bike, not with one that has idled for a bit (You shouldn't let these bikes idle long anyway). It is possible that the throttle plates stay too far open if the throttle bar set screw (the one the BMW manual tells you to adjust idle with) is set wrongly or the TPS is preventing the plates to close further.

There are a couple of issues here to work out. No.4 by pass screw is almost all the way out to get the mecury
in the  manometer to line up with the rest. Don't know why, have sealed all leaks, cleaned out the whole TB assembly, and compression is spot on with the rest.
And, I can never get the idle screw completely down, it's as if something stops it from hitting the stop. If I wind the screw down to the stop, the revs are too high right at the start. I had the "choke" cable completely undone
recently thinking that it might allow the throttle to close down, but still sat higher. If I push down on the idle screw with the bike running, the revs decrease to normal, but I cannot see where it could be getting caught up. Have had TPS body removed in case that was the problem, nix. I have the new style throttle cable installed, and it doesn't seem to me to have enough ability at the twistgrip end to allow a looser adjustment.

Thanks for all the advice, I'm a bit scared to touch those "untouchable" screws to adjust idle, as I'm a renown
stufferupperer.

Sounds like the butterfly in #4 closing earlier than the other three and prevents them to close enough.......

You don't need to touch those screws with the blue paint, just use a small hammer and adjust the other three butterflys to fully closed....  .

Oh man that means I have to go all the way back in there again. I am getting faster at it tho.
I also must have mis adjusted the TPS when I put it back on as it has become unbearably jerky around town.Wasn't too bad before.

A small hammer you say, I wonder if that is Skandi humour. Oh well, give it a go.

Here is one for each butterfly.......

All is not lost, rosskko is coming down on Saturday, we are going to do the rear seal, swap throttle bodies over and drink honey bourbon. Snow is forecast and if  rossco is riding you just know it'll be cold.

Two things to quickly check before you take the beast apart.

Clean the bypass holes out with a bit of carb cleaner and air.

Do the vacuum test again with the vacuum hose to the fuel pressure regulator disconnected and the spigot (?) plugged like the others.

If still not good close all bypass screws completely, put a coin under the throttle stop screw and do the vacuum test again. With bypass screws completely closed and the vacuum hose to the FPR not connected you get to see a representation of your throttle plate positions.

If still wrong you'll need to adjust them.

I think I can manage that thanks renez, seems a bit easier to start with.

Which rear main seal are you going to do Mate? Just posting this so I get a heads up with the much anticipated feedback.

Is it the one that Rossko says might improve the hot idle issue?

Ha, yeah maybe that's whats wrong. I'll do another thread for this one. I'm going to replace the throttle bodies with a spare after we get this seal done, hopefully it'll be set up right.
Rossko's on his way and it's -1 here. Sunny tho.

get some pipe cleaners bob

take those bypass screws completely out, as rene suggests

then probe the bypass ports with the pipe cleaners soaked in carbi cleaner all the way through ..you might be amazed at how much crap gets in there

inspect the needles of the bypass screws as well , you may have to get a brass brush to clean the crud off them as blowback of fuel coats them with some seriously hard to remove crud

then start from scratch on the adjustment

good luck with the seal stuff today ..

it was cold.

I watched the dogs eat their morning drink from the dog bowl.

I was sure the rear main seal was the source of the high idle. Seems I was wrong.

But the FIGJAM on my toast was wonderful. Shame I left my jar behind in my haste to see Waz in Wazzongong.
Doubt it will be their on my return.

BTW.

FIGJAM at RT's is actually jam made from figs.

Did you try to repolish the headers?

Looks like I've had a win. Rossko left behind his fig jam and some money and I got my new seal in. Sweet.
There are piccies but still in my camera.
Thanks Charlie, I think I did that once but can't rule it out. I'll be back in that part of the machine from tomorrow after all the grease and oil from the previous attempt has come off my hands onto the white towels in the bathroom.  .

I have removed my spares bike Throttle bodies and have created a dilemma for myself.

Apart from the obvious soda blasting clean up, what is that sensor thingo. It doesnt appear on my 85RT, this bike is an 86RT and that is an addition. Can I use this T/B as is providing I clean it and make sure that thing is actually working?? The other end of the electric cable disappears into No.1 throttle just next to the brass
adjustment screw. (close your eyes and picture it, my camera went dead). Although I fear the answer will be RTFM, some kind soul may be able to help me.

That is from a very early model that had a vacuum sensor there. It didn't work so they were removed and no other changes were made so feed it to a rubbish bin and put a rubber cap on the hole at #TB. It's the brass stub you use when a vacuum gauge is hooked up.

Thanks RickGman
now I have to clean it up and see if it looks ok.

Ok whilst cleaning replacement I played with Waz's Manometer. To get an idle below 1,000 at operating temperature, No.4 brass screw is completely screwed in tight (new O ring on it and cleaned out the whole hole) No.1 is about 2 turns out from closed.
2 and 3 are almost closed. If I loosen off No.4, then the revs immediately  start climbing, until
if I get the mercury anywhere near balancing, the revs are 1,500 and No.4 screw is almost out.

So before I pull everything apart, does this mean there is a leak somewhere? Please say yes. (only if you mean it, not to shut me up).

Please correct me if I'm wrong, but the only way that can happen is with air leaks on all cylinders but No. 4. Can you show us one with all brass screws closed?
This was with a warm engine and the valves are all withing their range re clearance, right?

Yes renez, hot engine (fan on and off) after a 60 klm ride, I have done all valve shims to spec, new T/B rubbers and re sealed bottom rubbers, new vacuum hose to fuel pressure regulator, and crankcase breather, new air filter. The only thing that isn't new is the O rings around the brass screws themselves. I cannot loosen off the idle screw anymore as it doesn't touch the bottom of the rail as it is, the choke cable is set correctly at cold start. 
I'll get a picture tomorrow with 1,2 and 3 screws all tightened, but it just makes their readings lower and the gap between them and 4 even more. I can stabilise the mercury all level by having No.4 almost completely screwed out but the idle is 1,500 rpm when I do that.
I can swap airflow meter if I decide to replace the T/B setup but it all sounds a bit weird now and maybe there is a more fundamental problem. If I take off the oil filler cap with the motor running the revs drop a bit.
Sorry to keep on about it but I'm perplexed. 
Bike runs smoothly and without drama on a ride, just too high at rest and in traffic.

What this is saying to me is that the butterfly on #4 is a touch further open than the others.  Because by turning the #4 screw in it is cutting of the air flow through the bypass and that fairly much equalizes and that air has to be coming through the butterfly.

Rick, are you certain. The higher vacuum is being shown at the no 4 unit. He said if he closed the bypass of 4 the vacuum goes up even further. Therefore my earlier comment; I feel the 'leakage' must be at all the other units.

How good are the o-rings of the injectors?

I would remove the TB's and have a good look to see what happens if you operate the throttle shaft. Take the bypass screws out and clean those holes with carburetor cleaner or, if available, a ultrasonic cleaner.

Basically, what you see with what you have done (new stubbs etc) is not normal, so open it up.

OK off she comes thanks. New rubbers on injectors a little while ago. I'm convinced it will be something simple
in the end, just need to find it. No time now till the weekend anyway. 

Yes Rene you are right but #4 is still out of sync and that I believe is where the problem is.

A quick update if anyone is around, No.4 Butterfly is 0.5mm more open than the rest at the throttle closed position. Is that too much, and how should I adjust that. Seems like the screw that should never be touched is the only way to do it, but that might put No.3 out as well.
Thanks.

go on ...touch it

don't be too afraid

Get thee behind me Charlie. I did a check of my spare bike T/Bs and guess what, exact same difference. In fact
No.4 is 0.5mm more closed at full throttle, not open as said before. I did find a few wet patches around the rubbers, and a couple of loose fuel rail bolts (must've been rossko) that might have let some air in past the injectors. The good news is it only took me an hour to get everything off down to the bottom rubbers. Must be all the practice I'm getting.
Such beautiful weather and I bought short riding boots from Aldi so have to get this sorted to get up north soon.

good work bob

it must be all the work to the old girl keeping those rubbers supple and easy to remove eh ?

I have noticed lag on the butterflys that are further away from the throttle cable ...I would imagine that over time (and with all the springs closing each tb ) that some movement in the linkages causes this issue ...perhaps ?

good luck mate

What is happening up this way that you can't miss. I haven't even told anybody about my plans for a Daintree gathering of the clan.

daintree ...???

wtf ....that's only like 1800 k s north of here (so that's 2800 for the sydneysiders - one way ) ...don't suppose we could do that and return trip in a weekend though ... 

Back on track :-)

It is important that all throttle plates are synchronised - that they are having the same opening at the same rail position. There are various ways to do it easily. You can put a small drill bit (you'll need two of the same size :-)) in between oneplate and check if the other bit fits the other plates. Bit agricultural. I normally get the rail a bit open (put a coin or similar under the stop screw and then measure with a slide gauge the clearance between the No. 3 plate and the top of the body, compare to the others and if needed adjust until they all measure the same. I know the only way to do it right is with a flow bench (thought about setting something up with an old vacuum cleaner and a anemometer but in the end couldn't be bothered), but the previously described way will get you close enough. If your anal you'll check a few positions through the range just to get the info ;-)

Thanks Renez, I used a sliding measuring aparatus to figure out where things were different, I'm a bit confused by the adjustment screw between No.3 and 4, as it looks like it will adjust both butterflies if I moved the screw
, Must be some technical knowhow required, but I'll have a go on the spare set first.

Daintree rick? geez louise that's along way. I just was after some sun.