Two things I did were to grind the 'brace' under the original cable bracket so that the bracket leans in more, providing the necessary angle, and ground away the tip so it fits between the plastic intakes. I also modded the TB end of the cable by carefully cutting away enough of the two layers of nylon so there is sufficient freeplay. The pics I posted in previous posts clearly show what I've done and my previous description is detailed enough to work out how to do it for yourveryownbadself. When you have all the bits to hand it'll become clear. I too am using the 20mm K1100 master cylinder and throttle cable.

As for fitting K1200 TBs to a K100, holes would have to be delicately drilled and tapped for air screws since nought but the castings exist there now. Be sure to source the 38mm variety (which came with cruise control models) and not the minimally increased 34mm versions.

35mm diametre K1100 TBs are the best overall ride-ability performance mod I have done to my K100. Eventually I will sort out an adaptor for the TPS, but for now it's not missed.

About lean running problem with 1100 TB`s,...if running lean in general....
Have you tried a adjustable FPR? It maybe only need a slight rise i pressure.

Inge K.

cheers mate !!

Thanks for the help and information updates, guys. I just picked up a K1100 throttle body assembly with FPR for $30 and (4) K1200 injectors for $40 from the net. So, when they arrive, I'll try out this modification.

Received the TBs and k1100 fuel injectors in the mail this week; looking very good.

I'm planning on replacing both the k100 TBs and fuel injectors with the K1100 TBs and K1100 injectors. That will give me larger intake size and greater fuel flow. Should I replace the K100 fuel pressure regulator with the K1100 fuel pressure regulator during this swap?

I know the K100 FPR maintains 36 PSI by use of the vacuum hose off TB4. The K1100 has no such vacuum nor can I find any specs on the FPR. So, I'm just thinking that maybe the K1100 FPR will regulate pressure higher to ensure good fuel supply to the 150cc/m injectors. Is that true (again no online wisdom on this subject found)? This is kind of related to Inge K's post above but I don't have access to an adjustable FPR.

TIA.

I found this pic, don't know if it helps.



Pretty sure Guest in the house used the k100 reg, i think from looking at the pic that the 1100 has one outlet to the reg. I thought that Guest said that they had a different setup to the K100. Guest could probably steer you in the right direction on this.

The K1100 FPR will be a bother to fit since it doesn't have a vacuum take off port. The image above from ETK is deceiving. I used the original FPR and simply kept it to the vacuum port of the No 1 TB. I also capped off all of the largish vacuum ports on each individual K1100 TB with pliable rubber caps similar to typical automotive vacuum caps (but bigger) and bought from the local hardware shop.

The K1100 and K1200 Injectors potentially flow the same amount of fuel, 150cc, as you say, instead of about 134cc of the K100 injectors. My bike uses almost exactly the same amount of petrol as before the swap (on average 20-22kms per litre) and there is a slight bit of soot round the tailpipe tip so she'd getting all the fuel she needs, and more. The bike idles rock steady at about 950rpm too.

Replicate the TB end of the throttle cable bracket like this, including grinding off enough of the bit where the cable rests against the stop and you'll be laughing.

robmack wrote:I know the K100 FPR maintains 36 PSI by use of the vacuum hose off TB4. The K1100 has no such vacuum nor can I find any specs on the FPR. So, I'm just thinking that maybe the K1100 FPR will regulate pressure higher to ensure good fuel supply to the 150cc/m injectors.

The K11 FPR pressure setup is the same as the K100 (2,5 bar / 36,26 psi).

Inge K.

Hi,

I was doing some work on the Kbike this weekend. I fabricated a simple linkage between the K100 throttle position switch and the K1100 throttle bodies I own. This was very simple to do and may work well. I can't say for sure until the bike is back together in the spring.

I started with a bog-standard M8x25 hex head bolt:


I filed a flat on one side leaving 8mm of thread near the head and cut 3mm off the end of the bolt to make the length 22mm instead of 25mm. I test fitted the keyed bolt into the TPS to ensure that the fit was snug and there was no free play.


Then, I fitted the bolt into the TPS and marked the head to show where to grind a slot. The way I accomplished this was to:
1) insert the bolt, and place a ruler across the head lining up with the middle of the mounting tabs of the TPS
2) rotated the hex head clockwise to make sure it was engaging the microswitch
3) drew a line with a black marker.

I then proceeded to grind a slot 4mm wide and the length of the head:


I fettled the slot with a file until it was a snug fit over the K1100 throttle body actuator arm.


The picture shows the modified bolt placed in the TPS.


I purchased a couple of nylon nuts with sufficient thickness to act as spacers. I am not sure about the consequences of having a large gap between the TPS and the TB but time will tell.

Awesome idea. That is just what I need to finish the job on my K11 TB swap when I return to OZ next year. Thanks for the simple and relatively easily fix, and the clear pictures too. To make mine work I was picturing a nylon bush or something in aluminium...but I've got tins of cast-off 8mm screws lying about...
Cheers.

Well, well, well, look at all the trouble I caused! Looks like you managed together to suss out all out. When my tech friend put K-1100 TBs on my K-100 we simply disassembled the original TB rack, disassembled the K-1100 TB rack, and swapped the K-1100 TBs into the original K-100 TB rack. We kept the stock K-100 injectors. Mathias has enough experience from his time with BMW Research to know this set up does not benefit from using K-1100 injectors. Too much fuel. Instead we make two adjustments to the air flow meter, one to loosen the preload on the vane spring one click or two (have to try each setting and see what works, but two clicks can be too rich sometimes) and to adjust the postion of the potentiometer wiper. This last one is excruciatingly sensitive.

Bravo on figuring out how to attach an L-Jet TPS on the back of a K-1100 TB. I did something similar out of a chunk of aluminum round stock. I discovered on the dyno that if you set the air flow meter bypass screw to give you 2% CO at idle, as soon as you crack the throttle the mixture goes way rich without the TPS. This is why the TPS has an idle enrichement setting. With idle enrichement AND idle CO set at 2%, as you crack the throttle the loss of idle enrichement is compensated for by the tendency of the mixture to spike rich off idle.

On the other end at WOT with no TPS, the mixture tends to go lean. Not dangerously so unless you spend a lot of time at WOT, so it's ok for most bikes in the US to go without a TPS. Eliminating the TPS eliminates the closed throttle fuel cut off above 2000 rpm and this makes off/on throttle transitions smooth, making technical riding on tight mountain road, or riding in the snow much smoother than it is with the TPS functioning. BMW test riders would disconnect the TPS of early K bikes for riding in the snow (R&D guys have big brass ones to ride in the winter in Germany!).

K-1200 TBs have no provision for a fast idle setting, since this is accomplished through the engine management on K-1200s instead of manually as on the K-100 and K-1100. If you do it, you have to be prepared to manually hold the throttle open on cold days until the bike warms sufficiently.

You noticed the four air fittings on the back of the K-1100 TBs. On my bike those are closed off as was done by our members here. You sussed that part out successfully. But here is what was done on my bike. I have all four TB's connected with vacuum hoses to the vacuum ports on each TB using plastic T connectors. Now the fuel pressure regulator receives a steadier vacuum signal than it can if it only reads vacuum off the rear cylinder. This smooths pressure variations in the fuel rail and makes for a bit smoother running. This is subtle stuff, but you can notice the difference. I have a bone stock K100RS, both with the long duration 284 degree cams, and the bike with the K-11 TBs is much smoother. My modified bike makes an honest 72 horses at the rear wheel. Not bad for an otherwise stock engine with a high quality valve job (port matching, 5 angle valve cut, knife edged valve guide bosses)

Now wrap your heads around the next increment. The current project is a used K-1100 engine, drive line and frame. But, my tech friend is yanking the four valve head and replacing it with a two valve head from a K100 The head is ported, combustion chamber shape altered, valve clearance reliefs cut into the piston crowns with a very nice jig a machinest friend of his made, and it will be fitted with 284 degree cams, K-1200 TBs and L-Jetronic. I have ridden the prototype. It makes about 115 horses, enough to lift the front tire easily. It makes power from 3000 rpm to redline and because the K-1100 bottom end has very short slipper pistons and 7 mm longer rods the engine is buttery smooth. The early head has more coolant in it and tolerates more power than the four valve head. Of couse we will use an early three row radiator.

We are building what will look like a very early K-100RT using 1985 bodywork (scored a complete used RT fairing with all the hardware for $350) and an early K100 wiring harness. No ABS, L-Jetronic, small battery, K100RS 16V footpeg plates, K1100LT front wheel and K1100 RS rear wheel (both 18 inchers), and early Fichtel Sachs K100 fork with the fork bridge built in, R100R Mystic triple clamp (less offset = more trail and no more K weaving and wallowing, but a machinest nightmare to implement ) and custom brackets to hang the K1100 four piston calipers on the stock K1100 rotors (already have something like this on my K100RS). We figure this will be a 565 pound wet weight bike that is going to surprise and awful lot of supposedly better machinery on the back roads. Btw, a first generation GSX/R-1000 conventional front fork bolts on too and works really well.

Ain't I a trouble maker AJ? Heh, heh, heh.

Awesome work Themason. Really interesting to read about the ingenuity people around the globe have to adapt and improve these old girls. I've not read anything of the like with any other base motorcycle than the Brick.

There is a guy on the other popular K-bike forum who is experimenting with a Megasquirt ECU in place of the standard Bosch unit on a K75. It's working at the moment but needs tuning, in his words. The TPS is replaced with a variable unit from a Volvo 740. Closed loop feedback is provided by a wideband oxygen sensor fitted to a bung welded into the collector of the exhaust. Timing is derived from the sparking coils. I believe the MAS is bypassed. He writes that the bike is much more fuel economic with this setup and performs better over the full power band. I'm following that experiment with interest.

I am contemplating fitting the K1100 TBs I have to my K75. I haven't read of anyone doing this to date so I guess I'm blazing my own trail.

robmack wrote:I am contemplating fitting the K1100 TBs I have to my K75. I haven't read of anyone doing this to date so I guess I'm blazing my own trail.

On the K-Bikes forum a guy have mounted K12 TB`s on a K75.

But I think the project never was finished.......it haven`t been any activity at the thread for a long time.

" I have all four TB's connected with vacuum hoses to the vacuum ports on each TB using plastic T connectors. Now the fuel pressure regulator receives a steadier vacuum signal than it can if it only reads vacuum off the rear cylinder. This smooths pressure variations in the fuel rail and makes for a bit smoother running. This is subtle stuff, but you can notice the difference."

As TM says in the above quote, I did this earlier this year, a noticeable difference, picked up the T connectors from a Pet shop(fish tank) but used proper vac hosing from motor dealer.

[quote="robmack"]Awesome work Themason. Really interesting to read about the ingenuity people around the globe have to adapt and improve these old girls. I've not read anything of the like with any other base motorcycle than the Brick.

There is a guy on the other popular K-bike forum who is experimenting with a Megasquirt ECU in place of the standard Bosch unit on a K75. It's working at the moment but needs tuning, in his words. The TPS is replaced with a variable unit from a Volvo 740. Closed loop feedback is provided by a wideband oxygen sensor fitted to a bung welded into the collector of the exhaust. Timing is derived from the sparking coils. I believe the MAS is bypassed. He writes that the bike is much more fuel economic with this setup and performs better over the full power band. I'm following that experiment with interest.

I am contemplating fitting the K1100 TBs I have to my K75. I haven't read of anyone doing this to date so I guess I'm blazing my own trail.[/quote]

I have ridden a couple of K-75s with K-1100 TBs. It is a nice upgrade. Both were converted to Paralever too.

One was bored to 70.5 mm with new Nikasil plating. It used K-1100 pistons and rods and there is headwork involved. That is a sweet running engine, probably the best possible K bike engine you can build, but finding a vendor for the Nikasil plating has kept me from doing one. Plenty of shops will Nikasil plate single cylinder barrels, but only one shop in the whole US will plate a block with multiple bores, and there are some problems with their workmanship. But, I can say I have ridden a K825 with a straight face because I'm telling the truth.

[quote="ungaas"]" I have all four TB's connected with vacuum hoses to the vacuum ports on each TB using plastic T connectors. Now the fuel pressure regulator receives a steadier vacuum signal than it can if it only reads vacuum off the rear cylinder. This smooths pressure variations in the fuel rail and makes for a bit smoother running. This is subtle stuff, but you can notice the difference."

As TM says in the above quote, I did this earlier this year, a noticeable difference, picked up the T connectors from a Pet shop(fish tank) but used proper vac hosing from motor dealer. [/quote]



Yep, aquarium parts reside on my bike too.

Themason wrote:I have ridden a couple of K-75s with K-1100 TBs. It is a nice upgrade. Both were converted to Paralever too.

Hmm, well I guess I'm not a trail blazer afterall. It's reassuring to know that my plan will work.

BTW, to set the idle speed on a standard K75/K100, one has to adjust the idle adjust screw. That same screw is set at the factory and is inaccessible on the K1100 TBs. Instead, one must adjust the brass bypass screws to adjust idle. Will this technique of adjusting idle work equally well on the K75 with K1100 TBs as has been proven to work on the K100 with K1100 TBs?

[quote="robmack"][quote="Themason"]I have ridden a couple of K-75s with K-1100 TBs. It is a nice upgrade. Both were converted to Paralever too.[/quote]Hmm, well I guess I'm not a trail blazer afterall. It's reassuring to know that my plan will work.

BTW, to set the idle speed on a standard K75/K100, one has to adjust the idle adjust screw. That same screw is set at the factory and is inaccessible on the K1100 TBs. Instead, one must adjust the brass bypass screws to adjust idle. Will this technique of adjusting idle work equally well on the K75 with K1100 TBs as has been proven to work on the K100 with K1100 TBs?[/quote]

That is how you are supposed to set idle speed on all the K bikes except the K-1200. Using the screw on the throttle rack disturbs the position of the throttle shaft relative to the TPS. This is why so many two valves per cylinder K bikes backfire. Owners set idle speed with that screw not thinking about how this affect the TPS setting. Ka-BAM! Always adjust idle speed with the bypass screws.

ok got a set of 1100 throttle bodies and i found a couple things the shaft fot the 100 and the shaft for the 1100 throttle body that works the tps is the same lenght i just swapped mine out and was a easy fix i had to file the shaft end with the nut on it to make getting the nut off easier. little lock tight and i rebraded the shaft cant change the throttle cable cam they are totally different i tried lol i also shortend my throttle cable housing by one inch to give me the extra lenght i need to still make it all work. and i did bend the cable holder just a tad cant wait to get them on to see how they work out

Good reading TWB was the trend setter well done mate. Mine is on the way and will swap out the individual TB's . You guys make it too easy for the rest of us
Halo

[quote="Halo"]Good reading TWB was the trend setter well done mate. Mine is on the way and will swap out the individual TB's . You guys make it too easy for the rest of us
Halo[/quote]
My K100 has had K1100 TBs since 2004 or so, but the tech who did this on my bike had done several other such conversions in the years prior to my conversion.

Very good Themason really just was talking about this forum can't wait price from America was less than 100 aussie all up
Halo

Coming soon will be K1200 TBs on a ported K100 two valve head, attached to a K1100 bottom end. I've ridden the prototype of this engine in another '84 RS and it is the smoothest K bike engine there is, and really good power over a wide rpm range. The engine is being fettled right now in the industrial wastelands of Long Beach California.

Themason wrote:Coming soon will be K1200 TBs on a ported K100 two valve head, attached to a K1100 bottom end. I've ridden the prototype of this engine in another '84 RS and it is the smoothest K bike engine there is, and really good power over a wide rpm range. The engine is being fettled right now in the industrial wastelands of Long Beach California.

Fantastic cant wait to see it is a great idea

I have also made the upgrade to 1100 TB. The only part that has to be fabricated is a small plate that holds the choke cable jacket.



All other parts can be exchanged between TB assemblies, and use the stock K100 TPS and accelerator cable pulley ....

Here is the modified K1100 TB ready to be mounted on K100 engine ( after cleaning ) :

[/url]

And here are the the shafts of the TPS ( long shaft stock K100 , short shaft K1100 ) :

[/url]

Aquachrono,

Did you substitute the K1100 throttle shaft with the K100 shaft? I see you're using the K100 TPS so you must have performed this swap. If so, was it a direct replacement?

I hope that you have plugged the inlet on the hose that connects the four back vacuum ports.

Why did you have to fabricate the choke cable support? There is one on the K1100 throttle body and the one on my TB fit with no issues. Was yours ruined in some way?

Hello Robmack,

The K1100 throttle shaft is a direct fit/swap so there is no problem using the stock K100 TPS. The hose connecting the vacuum ports it is from obvious reasons restricted with a plug and collar ( not yet in my pictures ) . The K1100 TB I purchased did not have the choke cable bracket so I had to fabricate one ( not a pretty one , I admit ) . Hope this helps...

All in all , I am happy with the results and it was a very cheap upgrade - less than 25 euro's ( including the K1100 TB ) .

I also purchased a K1100 center stand and I overhauled it completely - fabricated new bushings.Total cost : 30 euro .

Next project - bigger fuel tank ....

Just had a look at the throttle bodies on my k100 16v and see that they have the large pipe on the back of them, I assume that they are the same as the 1100 ones. The large pipe seems to be fitted to a plastic joint pipe and then another rubber pipe, where does it go from there?
@ aquachrono23, do you have any more details about the bushings that you fabricated for the centre stand? Material used and sizes?

@ bikerboy

Hardened steel was used for the bushing of the side stand and brass for the center stand bushings. Because the K1100 center stand I purchased had badly worn bushings and housing, OEM were not an option due to wear of the housing ( out of roundness ) . The housing was bored out and similar as OEM bushings fabricated at the necessary dimensions . I don't know the dimensions and it has no relevance since if you have a worn bushing most likely the housing is also damaged and a new OEM bushing will not last long. Bottom line is...clean and grease once a year is the best maintenance you can do to your center/side stand .

Thanks for that, I will have to get a bike stand and remove the centre stand to see how bad mine are.
Looking at your Avatar, if you are ever down this way and fancy a ride in a ULM then let me know....

Bob

Thanks Bob, ULM sounds great. I hope your center stand it's ok .

I know this is an old post but relevant to a later one of mine. I now have my K1100 bodies which despite coming of a 92 bike look brand new...bonus.

I'm really struggling with the throttle cable fit and how best to modify the early K100 bracket. I'm fitting these to a 1984 naked K100 with the old chain pull twist grip arrangement. I have 2 different throttle cables, one is the standard which fits the existing mid bar set up and which has a metal ferrule where it locates into the TB cable bracket. I also have a slightly longer one which has plastic ferrule. I'm using the standard early 8V airbox which means I can't use the K1100 cable bracket attached to the front of the TB's.

I have perused TWB's bracket modification but trial fitting on my set up suggests that the throttle quadrant will foul on the bent forward bracket when fully opened. I'm also unclear about modifying the actual cable as the locating hole on the K1100 quadrant is further round than the K100 one which means less free inner cable at the twistgrip end

Now Im going to facilitate the 8V TPS fit by swapping out the TB spindles as shown in aquachrono's post and I did wonder if anyone who has done this fit had attempted the same with the throttle quadrants ie swapping the 8V quadrant onto the K1100 TB's. I know this would also mean relocating the tick over adjustment screw but Im sure that wouldn't be a huge issue. How easy is it to remove said spindles are the nuts staked to the end of the spindles?? Im sure I read somewhere that you needed to grind the end of the spindle with the nut on to allow it to be removed and I'm anxious not to destroy anything

Incidentally I did note that on the first trial fit of the K1100 to the K100 inlet stubs, on rotating the cable quadrant, it wouldn't clear the inlet stub mounting. However a slight bend in the arm housing the tick-over adjustment screw allowed it to rotate cleanly. Just need to resolve the throttle cable attachment issue.

I realise that a lot of this probably isn't clear without photos and I'll try and put some up tomorrow.

Thanks

fent

Update

I have managed to fit these throttle bodies using an unmodified K100 throttle cable bracket. I ended up using the longer cable that came with the bike and stripping about 12mm off the plastic sheathing to give the required inner cable length.

This shows the difference in lengths of outer and inner. The metal feruled and shorter cable is the standard k100 one the longer plastic feruled on is a genuine BMW item and came with the bike amongst the spares but Im not sure what its meant to fit.




This shows where I pulled the plastic ferule down and stripped 12mm off the plastic sheathing. I then had to carefully cut the spiralled metal tube to gain the right amount of free inner cable at the twist grip end.

.

This shows the TB's fitted but with the TPS swap still to do. I have already removed the requisite spindle from the K100  throttle bodies and will do the same with the K1100 ones in order to swap them over and fit the k100 TPS. The keen eyed may note the additional metal collar under the plastic cable ferule. This was because I initially cut to much of the plastic sheathing and had to much inner cable slack. 12mm was the right amount to remove.




Im going to finish this conversion off with the uprated injectors from injectortune.co.uk.

Cheers

Fent

Getting prepped to make the swap to my '85 RT

K1100 throttle bodies

Before:


After (so far, that is)

[url=[url=https://s1008.photobucket.com/user/cash4brass/media/BMW K1100 Throttle Bodies/K1100CarbsAfter6_zps5e2971c0.jpg.html][/url]][/url]

Has anybody done this mod using RT/LT handle bars?

I dont seem to have enough cable length even using the K1100 LT cable...

hopefully this might assist

the early cable types had an adjuster about mid way down the cable ...just after the bend out of the forks area but before going under the tank proper

the later types had a continuous cable from handlebars to the throttle bodies ...but with an adjuster at the master cylinder location ,,,which was an addition

along with that came an different throttle body end bracket ...with a slightly different angle to the throttle bodies ...a plastic interferance adapter was added to the whole caboodle pictured in "fents post "

the featherlight cable (verry similar ...but slightly different to the "bmw version ") for the rt - lt versions could well be a good thing to do  for some planning the mod .

have look throught the motobins or motorworks sites ...you may pick up the differences i'm talking about

great before and after pics kyle ...


ill see if i have relevant pics if it helps   and any interest

Floyd

Do you mean you don't have enough inner cable to reach the point the cable nipple slots into the TB bracket?

I have a bare K100 (it has the small headlight fairing) with the standard handlebars and although the throttle cable had enough overall length, there was insufficient free inner cable length to extend to the point I needed it to. I bought another cable which was longer than my original and the photo that Charlie99 refers to in my previous post show the overall difference in lengths of the cable, however you will probably note that the available lengths of the inner cable are almost identical. I ended up simply cutting away about 12mm of the original cable sheathing and that gave me the inner cable length I needed.

Unfortunately another project has taken me away from this one and despite the fact that I have fitted the airbox, injectors and petrol tank I haven't had time to connect the fuel pipes add fuel and try starting her up. Hopefully in the next couple of weeks.

The only potential issue I will have with this set up is that once the airbox is fitted in its entirety I will struggle to reach the throttle stop adjuster on the TB bracket which is now at the rear of the assembly. I have pre-set it and left the actual air filter lower box off so I can make running adjustments if necessary.
 


Cheers


Fent

Fentible, you don't touch the throttle stop adjuster when setting the idle so your concern is not founded.  Idle is adjusted through the brass air bleed screws.  When you perform TB sync, you start with 1.5 turns out for each screw which gets you in the range of proper idle.  Then, once sync is achieved, dial in the idle speed by turning equally all adjusters in or out to lower or raise the idle.  Afterwards, double check sync and adjust if necessary. There will not be any need to access the stop screw.

Floyd, I had LT style bars on my K100 which was the first platform I mounted the K1100 TBs upon.  I routed the bowden cable between the frame and radiator, not the space in the frame near the headstock (where all the other cables exit).  That routing gave me the required freedom of placement that assured free throttle operation and enough cable length.

robmack wrote:Fentible, you don't touch the throttle stop adjuster when setting the idle so your concern is not founded.  Idle is adjusted through the brass air bleed screws.  When you perform TB sync, you start with 1.5 turns out for each screw which gets you in the range of proper idle.  Then, once sync is achieved, dial in the idle speed by turning equally all adjusters in or out to lower or raise the idle.  Afterwards, double check sync and adjust if necessary. There will not be any need to access the stop screw.

Hi robmack, thanks for your input. The initial problem I had, given the throttle stop screw had been wound fully out when I got the TB's, was setting it to the 'zero' position. I currently have it set where the throttle stop just meets the throttle quadrant stop at the closed position.  

This may be just ignorance on my part but does turning the throttle stop adjuster not achieve exactly the same outcome as equally turning the 4 bleed screws to achieve the desired Idle?? To my mind it just seems a lot simpler than adjusting the idle with 4 separate screws.

The answer to your question is in post #68 in this thread.  There must have been a good reason for the BMW engineers to provide a screw and then hide it way inside the engine compartment.  It screams "Leave me alone".  My experience is that using the air bleed screws works; it is not as convenient to move four screws versus one screw, but that one screw is very hard to get at.

I found that moving the screws a quarter turn each in the same direction and then measuring the effect on the idle is quick to do and works.  Screw them clockwise to decrease idle and counter-clockwise to increase -- each screw the same amount of rotation.

Ah..hadn't considered the impact on the TPS. Thanks for pointing that out and for the idle adjustment tip. Let you know how I get on.

Well I got the old girl started up today, she fired up no bother which is always nice when using non standard parts. I initially thought it was running very rich then realised that the smoke emitting from the silencer was grease burning off from the exhaust assembly.

The tick over was a little on the high side at 1200rpm but it enabled me to balance the TB's, an absolute cinch with  a set of dial vacuum gauges that I bought years ago. I've fitted a permanent 'T' piece in the FPR vacuum line to carb No. 4 which makes things a little easier. The tick-over was fine tuned using the bypass screws with a final check on the TB balance. The bike starts on the button, revs cleanly and ticks over nicely. I appreciate that only time on the road will prove if its running as well as it sounds and if the mixture is okay but fingers crossed.

Well done!  

Old topic, I know, but it inspired me to go the K1100 TB route. Because I had a spare set of K100 TBs too, I was able to do a bench comparison before taking the screwdrivers to everything and I finally figured out the whys and hows based on the descriptions above. So, what follows has already been done by others; I'm just adding a bit of detail.

I dismounted the nos. 3 and 4 TBs from both the K100 and K11 for the main work.

On no.4 TB remove the butterfly by unscrewing the two small screws in the centre. Unscrew the 10mm nut that holds the operating cam on; this allows you to slide out the butterfly actuating rods. The K11 one has a spacer on it; take it off and place it on the K100 actuator in the same place. Slide the actuator rod back in to the K1100 no.4 TB and screw the butterfly back onto the rod.



The rubber o-ring in the outside groove of the TPS seals the actuator opening.



TPS done.



You can also swap over the throttle quadrants so that you can still use the original cables (TB no.3). Now, there's a gotcha here depending on your bike. The K100 2V with a quarter throttle quadrant has a lefthand thread, the K1100 has a lefthand thread but the K100 2V with a half-circle throttle quadrant has a righthand thread. You need the throttle stop from the original TB setup too. The throttle quadrant and cable stop here are from a 'half-circle' engine.





Ready for mounting. Just ignore the fact that I've got the vacuum hose in completely the wrong place for now.

All of the 16V K100 models as well as the K1 use the same part number 35mm bore TBs as the K1100RS and K1100LT, which is 13 54 1 461 216. Did you mean to write K100 8V? Those all have 33mm bore TBs. Pardon if I read your post incorrectly.

Post edit for clarity! You're right of course - I shouldn't be talking about the 16V model.

Please bear in mind that I'm relatively new to modding bricks and it's entirely possible that I'll lift parts from one engine without realising that they didn't belong there in the first place.

The vakum connection at the pressure regulator should be connected to one
of the spigots for measuring the vakum (#4 is used from factory).
The idea is to keep the fuel pressure at 2,5 bar relative to the lower intake
port where the injectors is mounted.
The way it's connected now it won't function as intended since it's connected
above the butterflies...........

But on the other hand, it have been reported that owners have disconnected
and blinded this vacum connection...cause they haven't noticed any difference.

Dai wrote:Post edit for clarity! You're right of course - I shouldn't be talking about the 16V model.

Please bear in mind that I'm relatively new to modding bricks and it's entirely possible that I'll lift parts from one engine without realising that they didn't belong there in the first place.

To clarify further, whether we are talking about valves per engine or valves per cylinder, a 16V model is a 4V model since an 8V is a 2V.

Re-edited again - thanks, TWB.

Inge - I feel really stupid now, particularly as the 1990's Yamaha 650 and 750s ran a system called YICS which joined the intakes together to smooth out incoming pulses. It was also a trick we did on 650 and 750 twin-carb BSAs and Triumphs, so I have no excuse for missing that at all.

Edited to remove that

Where you now have connected the pressure regulator is the gas return
from the oil separator in the crank vent system on the 4V's....just blind it.