High Idle / Balance isues

[GORILA]

Rather than just looking at the gap In the throttle body butterflies you can measure this with feeler gauges. If the throttle stop screws have been 'messed about' you will see a difference. If adjustment is needed get the gap equal to the lowest or the unmessed one.

Also it is worth using the Dan Cata throttle body rebuild kits. Motobins seem to sell these. There are YouTube videos showing the rebuild process.I
From my own experience this is a worthwhile doing!

 

[chris ponkster]

Rather than just looking at the gap In the throttle body butterflies you can measure this with feeler gauges. If the throttle stop screws have been 'messed about' you will see a difference. If adjustment is needed get the gap equal to the lowest or the unmessed one.

Also it is worth using the Dan Cata throttle body rebuild kits. Motobins seem to sell these. There are YouTube videos showing the rebuild process.I
From my own experience this is a worthwhile doing!

I have fitted the Cata Dan kit - it cured the ticking but the two TBs were way out of balance. The stops have been adjusted and are now different to each other - Im going to GS Hell it seems! Both TBs seem to be sucking the same at idle and through the rev range . I have no idea why the two sides were so different - the bike has a lot of "previous owner issues".

 

[Hay Ewe]

Or you can get kits from Bing to rebuild the throttle bodies.....

 

[Hay Ewe]

Here are my thoughts…..on setting the throttle stop screws.

Everyone talks about setting the TPS value, but the bike will run and idle with the TPS disconnected, well mine does…. ( I guess The Motronic has fixed internal TPS value). So for me all the TPS does is act like an accelerator pump in a normal carburettor.

So for the purpose of setting the idle it must be possible to balance the throttle bodies by setting both Air bypass screws to the same position, then balance using the throttle stop screws. Once the throttle bodies are balanced and the idle is set correct, then reconnect the TPS and set the voltage at idle. Then carry out the rest of the higher RPM balance adjustment with the cable adjustment.

I’ve never tried it, because I haven’t rebuilt my throttle bodies yet, but I’ll give it a try when I do.

Anyone else got any thoughts on this….

Ian

Logic sounds good.
All mine have not been been tampered with so not going to try!
But yes, to me, logic is sound.

 

[Wrigsby1]

Here are my thoughts…..on setting the throttle stop screws.

Everyone talks about setting the TPS value, but the bike will run and idle with the TPS disconnected, well mine does…. ( I guess The Motronic has fixed internal TPS value). So for me all the TPS does is act like an accelerator pump in a normal carburettor.

So for the purpose of setting the idle it must be possible to balance the throttle bodies by setting both Air bypass screws to the same position, then balance using the throttle stop screws. Once the throttle bodies are balanced and the idle is set correct, then reconnect the TPS and set the voltage at idle. Then carry out the rest of the higher RPM balance adjustment with the cable adjustment.

I’ve never tried it, because I haven’t rebuilt my throttle bodies yet, but I’ll give it a try when I do.

Anyone else got any thoughts on this….

Ian

I once had to do that on a K1100 after some, possible more than one, ignorant mechanic had messed with them trying to find the lumpy idle... It was simply cracked inlet rubbers nobody had noticed... I even had receipts from the previous owner for the work .. sort of reverse engineering...

 

[chris ponkster]

I once had to do that on a K1100 after some, possible more than one, ignorant mechanic had messed with them trying to find the lumpy idle... It was simply cracked inlet rubbers nobody had noticed... I even had receipts from the previous owner for the work .. sort of reverse engineering...

Here's a thing - the bike apears to have had new inlet rubbers fitted at some point (one of the previous owners) - I may take them of and check if they have been fitted badly. Allthough I have the thing balanced and running ok I am not happy how I achived it - my dyslexic mind cant deal with why the TBs wouldn't balance just with the BBS - everything about it screams airleak to me - so even though its sorta fixed I will be taking it apart again!

 

[JohnnyBoxer]

I once had to do that on a K1100 after some, possible more than one, ignorant mechanic had messed with them trying to find the lumpy idle... It was simply cracked inlet rubbers nobody had noticed... I even had receipts from the previous owner for the work .. sort of reverse engineering...

Usually the L/H on 1100/1150’s

RH on early 1200’s to 2012

Spray some brake cleaner around the inlets, whilst bike is warm & idling

If revs rise ……inlet is cracked

I change LH inlet rubber every 10 years on 1150’s, costs about £70 from a BMW main dealer & use oem only

 

[JohnnyBoxer]

Here's a thing - the bike apears to have had new inlet rubbers fitted at some point (one of the previous owners) - I may take them of and check if they have been fitted badly. Allthough I have the thing balanced and running ok I am not happy how I achived it - my dyslexic mind cant deal with why the TBs wouldn't balance just with the BBS - everything about it screams airleak to me - so even though its sorta fixed I will be taking it apart again!

Spray brake cleaner on inlets at idle as I described above

 

[chris ponkster]

Spray brake cleaner on inlets at idle as I described above

I have done the spray thing and got zero results - been looking for an airleak for a while and found nothing, which is why I resorted to such a "shonky" way of achieving a balance of the TBs - but I still would like to find out why. I can't think of any where else it could be leaking enough to affect the idle speed.

 

[Ian J Hartley]

Are the actual positions of the butterflies in the throttle body at idle ( throttle closed) vastly different, or are you just concerned about the difference in the throttle stop screws between sides?

 

[chris ponkster]

So it goes on - one step forward and two steps back! After lots of lying on my back and squrting brake clean up I found a leak right at the back of the inlet at the bit you cant get to - strangly on the side I din't think had the leak which leads me to think that thye other side has a leak too at the bit you cant get the squrt at - BUT in the process of taking off the inlet rubber I snapped a bolt in the head - FARK - so I know what my next job is !

 

[JohnnyBoxer]

So it goes on - one step forward and two steps back! After lots of lying on my back and squrting brake clean up I found a leak right at the back of the inlet at the bit you cant get to - strangly on the side I din't think had the leak which leads me to think that thye other side has a leak too at the bit you cant get the squrt at - BUT in the process of taking off the inlet rubber I snapped a bolt in the head - FARK - so I know what my next job is !

Aha
So it was the inlet rubber!!
Which side LH or RH (as sat on bike)

 

[chris ponkster]

Aha
So it was the inlet rubber!!
Which side LH or RH (as sat on bike)

I found the LH one leaking - which is not logical for me as the RH side BBS was shut almost closed to get it to run - which makes me think that the other side inlet may be leaking too although I cant find it with the spray , but there is a bit I cant get to spray onto directly at the back of the inlet rubber.

 

[JohnnyBoxer]

I found the LH one leaking - which is not logical for me as the RH side BBS was shut almost closed to get it to run - which makes me think that the other side inlet may be leaking too although I cant find it with the spray , but there is a bit I cant get to spray onto directly at the back of the inlet rubber.

1100/1150’s it’s always the LH and never the the RH (unless an animal with hamfists has disturbed it) I have always found and both my 1150’s have had LH replaced in recent years and their throttle bodies were untouched (bar normal balancing at service, with vacuum gauges at service)

 

[chris ponkster]

1100/1150’s it’s always the LH and never the the RH (unless an animal with hamfists has disturbed it) I have always found and both my 1150’s have had LH replaced in recent years and their throttle bodies were untouched (bar normal balancing at service, with vacuum gauges at service)

The inlet rubbers look quite new so I thing at some point they were changed and I gues not tightened evenly

 

[JohnnyBoxer]

The inlet rubbers look quite new so I thing at some point they were changed and I gues not tightened evenly

They may look new, but not be new - they’re not a wearing part, as such (but must move a bit with a boxer twin, rumbling from side to side, at tickover)

Mine looked new from the outside and there wasn’t any real actual difference between the new and old, visually ….when replaced

Have you got factual evidence that they have been replaced ?

 

[chris ponkster]

They may look new, but not be new - they’re not a wearing part, as such (but must move a bit with a boxer twin, rumbling from side to side, at tickover)

Mine looked new from the outside and there wasn’t any real actual difference between the new and old, visually ….when replaced

Have you got factual evidence that they have been replaced ?

I don't have any actual evidence they were replaced - just based on how they look, also the one I took off doesn't apear to have any splits or holes - I can only guess it was leaking between the rubber and the metal head

 

[Pete.]

I replaced the shafts and bushes - but it is likely that someone fecked around with the stop screw before I got the bike. When I put the buterflys back in they had the same amount of light around them as before when shut. Is there anything I can do if they have be messed with?

The butterfly screws are straked to stop them backing out. Did you re-stake the screw ends when you replaced the butterflies? Also when you replaced them did you snug up the screws gently, back off the throttle stops then flick the throttles gently so that the blades were centred?

What shafts and bushes did you buy to re-fit? The shafts are hardened and suffer little wear even at good mileages. It's the bushes that wear and cause a rattle. I replace them with polymer bushes which stop the rattle and have lower friction.

 

[chris ponkster]

The butterfly screws are straked to stop them backing out. Did you re-stake the screw ends when you replaced the butterflies? Also when you replaced them did you snug up the screws gently, back off the throttle stops then flick the throttles gently so that the blades were centred?

What shafts and bushes did you buy to re-fit? The shafts are hardened and suffer little wear even at good mileages. It's the bushes that wear and cause a rattle. I replace them with polymer bushes which stop the rattle and have lower friction.

The shafts and bushes were quite worn. Yes the blades were centred and the nuts were red loctited and the bolt ends splayed with a cold chisel. I have definately found the problem - took off both intake rubbers and found where they were leaking even though it was hard to find the leak with a spray on the lh side. The intakes were leaking between the seal and the head - they had not split. not the greatest design imo as it only has two bolts and has a thin mating face with no gasket.

 

[chris ponkster]

Finally got it ballanced with the correct tick over - as the throttle stops had been interfeckered with by the previous owner it took a while to find the sweet spot as everything had changed once the airleaks were sorted. I am amazed how little a quantity of air will throw the ballance out at idle. Now for reliabillity trials