Good evening gentlemen

Was it a good idea to disconnect it?
Well, the answer at the time was a definite "yes."

Why? ..

https://www.k100-forum.com/t4341-short-lived-loss-of-power-intermittent-yet-v-specific

What about now, 6 months and some 4-5k miles on.

What a smoother ride, massively so. Before disconnection frequent loud backfires,popping on over-run all the time. Rider anxiety, ie quick overtake needed, change down, EXPLOSION ! Concentration disturbed... Has the tyre burst...etc etc.

Now, none of above in addition to original fault being cured.

Downside....fuel consumption.
Just worked it out. A difference.

I ride approx 9k miles year.

Before TPS disconnected. Riding with pillion, fully loaded,tankbag,everything,tent,you name it,hair straighteners and the rest! I averaged 10.5 miles/litre

After TPS disconnected. Riding solo with one toothbrush and iPhone! I average 9.5 miles/litre

Before disconnection @ current uk fuel price £1.35/litre annual fuel cost is £1197
After...................£1323

Annual cost to me of disconnected TPS is £126/annum.

Ie £2 /week.
Equivalent to 2/3 pint of London Pride real ale!

Weekly consumed units of LP real ale....never u mind!

Is it a good thing to disconnect the TPS? If you have had my prev probs then i would say its a yes. My last Mr K did the same backfiring and popping so I expect others will sadly do the same.

Best wishes to you all

Jonnyqq

Hiya jonny, just read this post and followed the link to your previous post ( I didn't have anything better to do ). Anyhow the symptoms you described and about it starting around 10 minutes into a ride, all sound very familiar to a very niggling flat spot I'm coming across. I've only had the Rs for a week so I'm doing a lot of trawling through forums for ideas and thoughts. When doing the disconnect , is it just a case of pulling the connector off. Does anything need blanking off?
If it cures it ill get you a pint.
Daz

First,let me thank you for the report. It's nice to see something accurate over few thousands KM.

I am too riding the solo bike with the throttle position switch unplugged.

Let's first review what I originally wrote about the function of the TPS:



When decelerating (switch 1 closes), the fuel injection is disabled until the rpm goes down to 2000rpm. If the engine is still decelerating and the rpm is lower than 2000, the EFI is re-enabled and the injection is controlled again by the FI computer. As an example, when riding at 5000rpm and cutting the throttle, the injection will be cut off between 5000 and 2000rpm.
This switch assembly only signals idle or full throttle to the EFI. Mid throttle signal to the EFI is controlled by the vacuum switch.

When you twist the throttle, the same switch (contact # 2) will tell the EFI computer that the engine is on full load and the mixture air/fuel will be enriched.

------------------------------------------

Now, by disconnecting the TPS, we are missing the function to enrich the mixture when on full throttle.

What I am thinking now, is to modify the wiring of the TPS to keep only switch #2 working in order to still have the extra power if needed (Very seldom but....)

I am planning to re-plug the TPS and modify the wiring to only disable switch #1.
Then, setup the TPS to get switch #2 contacting earlier. This way, I should get the 'extra' power before being on full throttle.

Another brain fart


About the extra gas cost.... It's compensated by the rear tire life being longer

CF

Dazco, disconnecting the TPS is a misleading comment.

You do not unplug it. You adjust it so it doesn't activate.

The unit is held in place by two screws that need to be loosened and the unit is rotated a few mm to stop it activating.

I have adjusted mine also and the difference when riding two up is huge. Much smoother.
Hope this helps

rossko

rossko wrote:Dazco, disconnecting the TPS is a misleading comment.

You do not unplug it. You adjust it so it doesn't activate.

The unit is held in place by two screws that need to be loosened and the unit is rotated a few mm to stop it activating.

I have adjusted mine also and the difference when riding two up is huge. Much smoother.
Hope this helps

rossko

I fully agree with your comment.

Rotating the switch counter clockwise should disable it when decelerating and activate early when you need more power.

CF

As mentioned by the others adjustment of the TPS stops the backfire. Disconecting it gives smoother response in stop start traffic and tight twisting road riding. I wouldnt have thought there would be worse economy... Ned is the "expert" on the TPS wonder what he thinks?

Ghost who rides wrote:As mentioned by the others adjustment of the TPS stops the backfire. Disconecting it gives smoother response in stop start traffic and tight twisting road riding. I wouldnt have thought there would be worse economy... Ned is the "expert" on the TPS wonder what he thinks?

Hi,

I had my TPS disconnected and then "tuned out" for approx 3 years. I haven't noticed any changes in fuel consumption.

We did discuss this at some length see: https://www.k100-forum.com/t934-things-that-bmw-put-there-to-annoy-me.

In my case I decided to look into it because I often ride roads with hair pin bends and slow corners. As you can imagine, smooth throttle is a must. I think that it was Themason who commented a number of times that BMW test riders would also disconnect it when riding in the snow or in slippery conditions. I can understand why I think that Ajays was the guy who come up with the "tune out" procedure.

My advice is : disconnect first and if it works for you, adjust as described above. One thing is certain... you can't damage anything by making this mod.

Ok,with TPS,the EFI is disabled until engine revs drop to 2000. When TPS disconnected the fuel is utilised during the drop to 2000. Wouldnt this account for my increased fuel consumption

jonnyqq wrote:Ok,with TPS,the EFI is disabled until engine revs drop to 2000. When TPS disconnected the fuel is utilised during the drop to 2000. Wouldnt this account for my increased fuel consumption

Very hard to say. In principle yes, but it all depends how often and how long you spend in that position.

In my case, a few tight uphill corners and roundabouts is enough to spoil my ride, but not enough to show up in the fuel consumption figures.

Crazy Frog wrote:I am planning to re-plug the TPS and modify the wiring to only disable switch #1.
Then, setup the TPS to get switch #2 contacting earlier. This way, I should get the 'extra' power before being on full throttle.

Another brain fart

I wonder if you will achieve the goal you intend. Won't the TPS limit the maximum rotation of the throttle butterfly shaft? The TPS has a hard stop in its design once the switch contacts #2 close (to prevent damage to the switch). If it does have a limit in the number of degrees of rotation, by mal-adjusting the TPS to engage WOT earlier in the rotation, it will cause the butterflies to not open fully at WOT. You have achieved an earlier engagement point but not increased the range of rotation through which the switch contacts remain closed.

robmack wrote:

Crazy Frog wrote:I am planning to re-plug the TPS and modify the wiring to only disable switch #1.
Then, setup the TPS to get switch #2 contacting earlier. This way, I should get the 'extra' power before being on full throttle.

Another brain fart

I wonder if you will achieve the goal you intend. Won't the TPS limit the maximum rotation of the throttle butterfly shaft? The TPS has a hard stop in its design once the switch contacts #2 close (to prevent damage to the switch). If it does have a limit in the number of degrees of rotation, by mal-adjusting the TPS to engage WOT earlier in the rotation, it will cause the butterflies to not open fully at WOT. You have achieved an earlier engagement point but not increased the range of rotation through which the switch contacts remain closed.

Good point Rob.
Maybe only disabling switch #1 will be enough and I will keep the best of both worlds.
No cutting of the injection when decelerating and a bit of extra power at full throttle.

Read this thread earlier and went out to the shed dragged a TB for a K100 out of the heap of bits under the bench and measured the position the WOT closes and it closes after the butterflies go past the point that the shaft takes more space on the throat than the butterflies. You could go back 2-3 deg and it still would make no difference so just turning the TPS back till the closed throttle switch becomes inoperative without any detrimental effect at all. Just turn it back till it just doesnt switch and thats all you need to do. Wish I could find a way on the K1100. The K100 was fairly good and I didn't do anything but this K1100 is another kettle of rotten mullet. The mechanics at Motohansa ( Sydney's big dealer) really made a mess of it.

I've been trying out disconnecting the TPS for the last few runs and thought that there was a flattening off of the power at full throttle. I do find it a lot smoother without the TPS.
Today I did a couple of hundred miles and after the first 50, reconnected the TPS. The full throttle power is back again. Its noticeable when you just need that bit of lift for overtaking. Without the TPS it flattens off about 80mph but with it, it zips on up to 100mph with no problems.
My conclusion is that you really do need the No.2 switch.
I think Bert's idea of disconnecting the No.1 switch is the way to go. That way we won't take a chance on messing up the fuel mixture by enrichening it too early if we just tweak the TPS.
Which colour of wire do we cut, Bert? The red one or the blue one?(old movie joke)

Comberjohn wrote:... 80mph but with it, it zips on up to 100mph with no problems...

love the 80 to 100 mph acceleration gains with the public holiday last Thursday and demerit points, that would be the end of my licence for a year or two

BTW from memory, one can get the same effect as WOT if you hit the starter motor button when needed? yes?

Seriously, I am all for keeping the WOT function in place as you may need it. I believe that, realistically, Rick's analysis and conclusion about the WOT is absolutely right.

Ned wrote:

Comberjohn wrote:... 80mph but with it, it zips on up to 100mph with no problems...

love the 80 to 100 mph acceleration gains with the public holiday last Thursday and demerit points, that would be the end of my licence for a year or two

BTW from memory, one can get the same effect as WOT if you hit the starter motor button when needed? yes?

Seriously, I am all for keeping the WOT function in place as you may need it. I believe that, realistically, Rick's analysis and conclusion about the WOT is absolutely right.

I guess that we are all in agreement that disconnecting the TPS is not the best thing to do but disconnecting switch #1 accomplishes what we are looking for.
Who will be the first one to try it?

I would certainly do it but today I had a huge set back.
I was planning to get the sidecar out of the basement and use it for the first ride tomorrow, but I fuck..ed up something on the clutch and get a grinding sound when I clutch in. This afternoon, I put the bike back in pieces to find what is the problem.
Because of the way that the sub-frame is mounted, even the front fork had to be removed. It took me only a 3 hours work to have the gear box off.
Next week, I will investigate the problem. Tomorrow I will use the solo bike
Here is what left of the bike tonight...

Oh gosh Bert,sorry to see that, looks terribly familiar (bad memories flash back.)
Anyway,i'm going to get the old TPS off Mr K 1 and await the development on this thread re: the quest to disable switch-1.
Not that i think i need to but it sounds fun and willing to have a go. Of course,as the acknowledged worst mechanic on this forum I will wait.

Ned wrote:

BTW from memory, one can get the same effect as WOT if you hit the starter motor button when needed? yes?

Unfortunately the starter button is isolated unless the clutch or neutral switch is operated, so you would only get the boost with no drive or in neutral..........and that would defeat the object.

Paul.

I was thinking more on the lines of overtaking a car or cars while winding the throttle open, watching the corner ahead AND having the presence of mind to hit the starter button!
The TPS mod is the way to go.

Yes, my memory is not what it used to be and hitting the starter button at speed somehow feels wrong

On my bike the Idle Switch (#1) is tuned out, or adjusted out of operational as described by Ajays some years ago and the #2 is operational.

BUT, can I suggest another use for the #2 switch?... As its function is to squirts in more fuel why not connect it up to a Nitro Kit ... Mad Max mod? Sure why not! after all there is plenty of space for a small bottle under the seat or inside those huge air boxes and the WOT micro can actuate the NOx relay.

After watching Rossko and Klompy ride away into the sunset yesterday, I am sure they would take this mod seriously

I have to say this.
I have extensive experience in dragracing especially bikes. I was the Number 1 plate holder in 1980-81-82 and retired undefeated with a bounty on me ie the first person to beat me without benefit of a red light or breakdown would collect.
I also ran a blown alchol dragster with a 454 Chev and 3 speed lenco gearbox for the next 2 years.
Enriching the mixture is only neccessary at the initial opening of the throttle to prevent bogging down.
The best ratio for petrol/ gasoline is 13.2 - 1 and that will give the most horse power (dyno proven many times) and Methanol 6.1 -1 mix without causing uncontrolable high combustion chamber temperatures and fried engines. Many of the dragracers use a high speed leanout which will lean out as much as another 2 points 15 - 1 mix and 7.4 with methanol and I can tell you from experience that when you hit the high speed lean out it like a kick in the arse and that is when the engine starts making a heap of horsepower but if you hold it for too long (around 3 seconds then all your pistons dissapear out the exhaust in a puff of grey smoke). Hence the term "smoked an engine"
You dont need to enrich the mixture when accelerating except for the initial throttle opening. The carbies on cars use a pump to give a squirt of fuel and then return to running on the main jet.
A slide carbie like many bikes used dont have that so need to run a bit rich all the time and the CV carbies that the Japaneese bikes used enriched the mix by a drop in the slide making more vacuum and sucking a heap of fuel up the main jet then very quickly the slide opened and away you went at normal mix.
Hitting the start button does nothing because there is no power to it when the bike is in gear with the clutch engaged and even if it did enrich the mix it would do nothing except make a bit less horsepower because the mixture is not optimal.

Ned wrote:
After watching Rossko and Klompy ride away into the sunset yesterday, I am sure they would take this mod seriously

Be thankful you could see us and was not left in a cloud of blue smoke.
All that noise was the krazy Mr Klompy.

What you didn't see Ned was directly over the little hill we disappeared behind was a stop light. Landslide had narrowed the road to one lane.
Mr Klompy took off all noise and exhaust only to be halted 10 metres away.

Nitrous eh? Mate had Metho injection on his Torana. Would that work?

Water injection is very good as it helps to contain combustion chamber temperatures and a bit of methanol is even better and it keeps the combustion chamber spotlessly clean. You need to get a good quality kit. To add a bit more it is an absolute marvel if you also use LPG as a fuel.

One thing that I don't like about water and methanol is that they are liquid and the plumbing may be a problem.

Although I had my tongue firmly planted in my cheek about the intro thing, a quick search uncovered kits for bikes, so it obviously works a treat. For $500 and a place to put a 500g gas bottle and a relay they talk about 20 to 40 hp gain.

Check this: http://www.1tail.com/MPS_Racing/Nitrous_Kits/Universal_MPS_Dry_Nitrous_Kit_for_Fuel_Injected_Motorcycles_-_1-0323/732243/

As for Klompy ... yep, I could see a cloud of testosterone as he took off... I did like the noise. At 8000rpm she sounded great

I wouldn't use Nitrous on an engine, I have seen just too many destroyed engines to have a liking of the stuff.

the tps switch puts a loop condition into the circuit when throttle closed. I have a switch in series with this, mounted on the dash. With the switch in the off position (tps loop disconnected) there is far less engine braking, so an added cost may be brake pads. With the type of riding that i do (commuting through city traffic). i always have the switch in the on position to provide engine braking, but for touring through open country,would probably have the tps switched off.

sven k100 wrote:the tps switch puts a loop condition into the circuit when throttle closed. I have a switch in series with this, mounted on the dash.

Excellent idea.
Easy to do, and very efficient way to enable/disable the TPS on the fly.

I have been following this thread with interest like a few others and find all the comments interesting.
But can I ask one question from those who have disconnected the low setting or, even better, put a switch into the loop in order to give the extra engine braking if and when required. Think sven k100 was the one.
Which colour of wire do we break into?
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I'm guessing its either the black/white or the brown/white.
I want to do the same switch mod myself.
Did consider tweaking the switch itself but its almost impossible to release the adjustment screws, especially the inboard one, without major surgery.

I was just looking at this thread on same subject, and it is apparently the black/white wire for the closed switch

https://www.k100-forum.com/t934p50-things-that-bmw-put-there-to-annoy-me#73287

Thanks Jim. Someone posted the info just after I put that up. Already made the cut and much prefer it.
Although may fit a switch at some point to give me the option.
Switchable riding modes? 
Had it for decades.(just didn't know it!)

Comberjohn wrote:Thanks Jim. Someone posted the info just after I put that up. Already made the cut and much prefer it.
Although may fit a switch at some point to give me the option.
Switchable riding modes? 
Had it for decades.(just didn't know it!)

 Haha....I go down some pretty steep grades, so having it switchable is an excellent idea!

I have been wandering around this site taking in all of the collective knowledge to help me get my bike back to her glorious self.  I read the TPS thread with interest as the throttle was neither smooth at roundabout speeds and seemed to lack punch when accelerating hard.  
I got quite a surprise when I took the TPS connector off as it was completely corroded.  The male pins were all covered in verdigris and the central female pin was the same. 

Q.  I wonder what that was doing to the TPS ?

I am going to leave the TPS out of circuit for a bit and then try it again with the TPS re-connected ( and the connections suitably treated with DeOxit).

I don't know if it has been said today, but this forum is full of some bloody clever people.  

cj ....here is what I use to get to the "Phillips head " screws around the mounts for the tps undone .

it makes the job sooo easy (and happens to be a very handy little tool that is always in the tail of old "gerty")



reminder if you don't want to disconnect or cut anything to give having the tps non effective 

just turn the mechanism slightly anti clock wise

what you are looking for is ...that the switch action cannot be heard on throttle closure .
if you want to restore the operation its pretty easy to get it back ....no ?

this way you will still have the "wot " (wide open throttle position switch ) still active which gives a slightly richer mix when up on near full throttle

I've wired a switch between the blk/wte wire on the TPS and installed a switch on the dashboard....

Looking forward to trying it after I get the water/oil pump back on..

Some of you might be interested in the new thread I've started 'TPS  the next step?'.
Slight variation on fitting a switch. Hope to try it out soon.

I am about to fit a switch into the black/white TPS wire, and the intelligent debate on this forum has got me thinking......

The TPS shuts off fuel to the engine when the revs exceed 2,000 rpm and the throttle is closed.  This is supposedly for better emissions and fuel economy, but one thing that really stood out when I first rode my K was the tremendous engine braking.  It is so good that I have had to recalibrate my brain so that the throttle is kept open for longer on the approach to hazards.  If the throttle is open for longer then are the gains in fuel economy and improved emissions spurious?

I have a log over the past 1,000 miles of fuel economy with the TPS functioning, so it will be interesting to see exactly how much it gets when the TPS is disabled.

xpc316e wrote:I am about to fit a switch into the black/white TPS wire, and the intelligent debate on this forum has got me thinking......

The TPS shuts off fuel to the engine when the revs exceed 2,000 rpm and the throttle is closed.  This is supposedly for better emissions and fuel economy, but one thing that really stood out when I first rode my K was the tremendous engine braking.  It is so good that I have had to recalibrate my brain so that the throttle is kept open for longer on the approach to hazards.  If the throttle is open for longer then are the gains in fuel economy and improved emissions spurious?

I have a log over the past 1,000 miles of fuel economy with the TPS functioning, so it will be interesting to see exactly how much it gets when the TPS is disabled.

As ComberJohn stated, you should have a look at the solution posted HERE.
This should gives you all the flexibility needed to set the TPS according to your mood or riding pattern.

CF

Where exactly is the TPS unit on the bike?... and is it a simple matter of cutting the black and white wire once I've found it?

You can find the TPS on the left hand side of the engine, on the end of the rod that operates the butterflys on the fuel injection.
It's a small black box and a lead with a 3 pin connector that plugs into the top of it. You can't miss it.
Why not 'try before you buy'.
Unplug the 3 pin connector and try it first. 
The bike will run as normal except that you don't get the same engine braking as before. My belief is that the response is affected at full throttle when the connector is unplugged but that's been a matter of discussion in the forum.
Doing this will certainly allow you to try it before cutting any wires. Others in the forum seem to prefer having the increased engine braking.
I cut the black/white wire at the start of the summer and find that I much prefer the smoother way it drives.
The other option is to fit a simple switch which gives you the choice.

Many thanks John... I'll have a look in the daylight tomorrow and report back.

Another option is to loosen the adjusting grub screws and rotate the switch so that it does not activate when the throttle is closed.  This doesn't involve any cutting of wires and allows you to reset it again if you don't like it.

Located the plug as instructed and disconnected. Result is a much smoother ride in slow moving traffic. Very impressed with the result and will not be reconnecting.
Is it wise to leave it unplugged or do I need to reconnect the plug and disable just the black and white wire (or rotate the switch as suggested)?
I think what I'm asking is, What do the other 2 wires do and do I need them?

Firstly, leaving it unplugged will not do any harm. Although I would be wary of water getting into the TPS.
Regarding what the wires do. The TPS has two contacts, one cuts the fuel injection when you close the throttle until the revs drop to below 2000 rpm. Hence the sharp engine braking.
The other contact supposedly enrichens the injectors at almost full throttle. The other wire would be a power feed for whichever contact is in use at the time.
My opinion is that the slight enrichening at full throttle, when overtaking for example, is useful. I thought that the engine flattened off at above 80mph without the TPS connected. Others in the forum disagree.
As you seem to prefer it without the TPS you have two options.
You could simply cut the black/white wire as I have. Simple to reconnect if you change your mind and it keeps the full throttle setting the same as intended by the factory.
You can also rotate the TPS to 'tune out' the lower contact. The problem that I found was releasing the inside screw on the TPS bracket in order to rotate it. Its difficult to get at.
Whichever method you choose I don't think you'll go back.

Once again thank you... I shall be taking the pliers to it first thing in the morning.
1st ever bike mod... giving myself a pat on the back.

Oh dear. This is only the first of many mods. 
There's no known cure for a dose of K pox.