Throttle body adjustment gone bad. Save my summer!

Post Reply
slowdown
125cc
125cc
Posts: 39
Joined: Sun Feb 04, 2018 7:44 pm
Country: United States
City: PORTLAND
Year: 2014
Colour: Black & Orange

Throttle body adjustment gone bad. Save my summer!

Post by slowdown » Tue Jul 30, 2019 2:49 am

'm always breaking stuff on my bike, and I probably shouldn't try to work on it, but I continue to do so.

I have a '14 1290R, almost 28,000 miles. I absolutely love it. Best bike I've ever owned. I ride the piss out of it. It's my favorite thing to do. I'm really hoping I didn't kill it.

Some time in the past 10k miles or so I started noticing that my idle was hanging for a few seconds around 2250 RPM when I let off the throttle. A quick throttle blip will also make it hang for a couple seconds. After a couple seconds it would drop to 1400, which is the appropriate idle RPM. Very rarely when I'm riding I'll let off the throttle and expect some engine braking to occur as it normally does only to be surprised that the bike keeps sailing at current RPM for a second or so before starting to compression brake. It almost feels like the bike is floating. Kind of strange.

I read some threads on various sites and found this to be a relatively common issue, especially for people with the mods that I have done (Rottweiler airbox, de-cat, cannister/SAS removal, PCV, Remus midpipe and Remus can). I read a bunch of people saying that balancing the throttle bodies will fix the issue. I found a long thread on superduke.net where a bunch of guys had luck bench syncing their throttle bodies.

So I tried it, and now my bike runs like complete shit.

I took off the tank and airbox to have access to the throttle bodies and the adjuster screw.

I pushed the linkage arm so that the valves were wide open (using the throttle with the bike on but not running will only move the valves 1/4 open max), and measured the distance that the front valve was open versus the rear. I adjusted the rear to try to bring its measurement closer to that of the front. The front is not adjustable. I didn't know if turning the screw clockwise would bring them closer to the same measurement, or if I needed to go counterclockwise. So I tried both and re-measured several times.


In the end this resulted in two full turns of the screw clockwise, which seemed a lot (the screw has yellow paint on it, so it's easy to know when a full revolution has occurred). The measurements had come closer together, so I put everything back together, started it up, and IT RAN LIKE SHIT. The bike was visibly shaking/juddering, it idled lower than it should, and it had this terrible resonating sound, so I killed it. I backed the screw off 1 turn and tried again, and it was still shitty, but not as bad. I decided this was no good, so I tried to put the screw back the same position it was before I started.

I put it back to where I believe is the original position, but the bike still runs worse than before. The hanging idle is gone, but the bike is running badly, and I'm not sure what to do with it. I let it idle for 10 minutes (fabled 10 min reset), and it ran a little better when warm, but on my commute today it ran like $HIT all the way home.


Symptoms:
Idle RPM seems to drop to 1250 sometimes coming back to 1400
Engine is stumbling through 1250-3000 RPM in first gear, much worse than it ever has
Engine wants to stall when taking off out of first gear (nearly dumped me today making a left turn from a stop when it abruptly stalled halfway through the turn)
Engine will occasionally stall when giving a quick throttle blip in neutral
Strong smell of gasoline when coming to a stop
Intermittent shaking/juddering
Questionable ticking sound when engine is running
Just doesn't feel right.


If all I did was turn a single screw, and then put it back to its original position, why am I having all these issues? I guess its possible that I miscounted the number of revolutions and the screw is +1 or -1 from its original position, but I don't think that is the case.

Would hooking up a vacuum gauge to the bike and balancing that way help? I'd love to do that, but I can't figure out how to get access to the adjuster screw while the bike is running (tank/airbox are in the way) in order to make adjustments in real time. I also read somewhere that KTM says the throttle bodies on these bikes can't/shouldn't be mechanically adjusted (then why is there an adjuster screw?). I don't know why that would be the case, but I read it in a couple places.



Here's some pics/vids
Valves (little dirty right?)Image

Adjuster screw
Image

Valve wide open
Image

Throttle body motion with engine off:
https://www.youtube.com/watch?v=7KXvyHV ... e=youtu.be

Engine idle, ticking sound:

https://www.youtube.com/watch?v=T-xz4MU ... e=youtu.be
Last edited by slowdown on Thu Aug 01, 2019 9:58 pm, edited 2 times in total.

mrossk
500cc
500cc
Posts: 155
Joined: Tue Oct 27, 2015 1:46 am
Country: usa
City: santa fe
Year: 2015
Contact:

Re: Throttle body adjustment gone bad. Save my summer!

Post by mrossk » Tue Jul 30, 2019 4:17 pm

is it possible you didn't get one of the sensors fully plugged back in when you put the tank back on, or perhaps the fuel line connector isn't fully seated? When I was recently cleaning my air filter, the male part of the fuel line quick disconnect broke (it's a cheap plastic part), but as it was still sitting in the female part, the bike still ran, just poorly, and I smelled fuel. Or, maybe the air pressure sensor? (I also did this "mechanical balance" and it helped, so you "should" see improvement) Good luck!

slowdown
125cc
125cc
Posts: 39
Joined: Sun Feb 04, 2018 7:44 pm
Country: United States
City: PORTLAND
Year: 2014
Colour: Black & Orange

Re: Throttle body adjustment gone bad. Save my summer!

Post by slowdown » Tue Jul 30, 2019 11:02 pm

Hmm, interesting. I can certainly check the high pressure fuel line, I've had the tank on and off about 10 times in the past week. I guess its certainly possible that fueling is being compromised by a bad connection.

Where would I find the air pressure sensor? I see it on the parts fiche here(parts 3, 4, 5, 6): https://www.partsfish.com/oemparts/a/kt ... ottle-body

I'm not sure where on the throttle body that is located. I don't think I have messed with it at all.

mrossk
500cc
500cc
Posts: 155
Joined: Tue Oct 27, 2015 1:46 am
Country: usa
City: santa fe
Year: 2015
Contact:

Re: Throttle body adjustment gone bad. Save my summer!

Post by mrossk » Tue Jul 30, 2019 11:17 pm

it's the plug that connects to the airbox (or at least I thought that's what it is) And there are those 2 other connectors that are disconnected when you remove the tank...I forgot what they are ;)

slowdown
125cc
125cc
Posts: 39
Joined: Sun Feb 04, 2018 7:44 pm
Country: United States
City: PORTLAND
Year: 2014
Colour: Black & Orange

Re: Throttle body adjustment gone bad. Save my summer!

Post by slowdown » Wed Jul 31, 2019 2:08 am

Hmmm.

I have the Rottweiler airbox, so not sure if its different. The only sensor I can think of on the Rotty airbox is the air temperature sensor that is OEM on the bike and re-used with the rottweiler system. There's also the crank case breather hose on the rear part of the airbox... Is there another sensor?


As far as tank removal, I think all the connections that must be un-done are the vent/drain line, high pressure fuel line, fuel level indicator and fuel pump electrical connector. I will check those. How much did a new high pressure fuel line/connector run you?

mrossk
500cc
500cc
Posts: 155
Joined: Tue Oct 27, 2015 1:46 am
Country: usa
City: santa fe
Year: 2015
Contact:

Re: Throttle body adjustment gone bad. Save my summer!

Post by mrossk » Wed Jul 31, 2019 3:19 am

You're right- it's the temp sensor, not pressure, sorry. I happened to have a spare fuel connector from a previous bike (MV Brutale, which notoriously had problems with such) , I can't remember what I paid. But it's all stainless, instead of plastic, which is nice. Can't remember if it's a 5/16 or 3/8" barb, but I got it to fit.

slowdown
125cc
125cc
Posts: 39
Joined: Sun Feb 04, 2018 7:44 pm
Country: United States
City: PORTLAND
Year: 2014
Colour: Black & Orange

Re: Throttle body adjustment gone bad. Save my summer!

Post by slowdown » Wed Jul 31, 2019 3:57 am

Cool. Did you use that fuel line to sync the throttle bodies with a manometer when you made you made your adjustment? Or did you just bench sync it?

mrossk
500cc
500cc
Posts: 155
Joined: Tue Oct 27, 2015 1:46 am
Country: usa
City: santa fe
Year: 2015
Contact:

Re: Throttle body adjustment gone bad. Save my summer!

Post by mrossk » Wed Jul 31, 2019 3:54 pm

I did the mechanical sync, using two 1/2" router bits (that I checked with a micrometer). You would need some long fuel line, or an aux tank I think to sync with the mercury sticks. I learned the hard way to attach something to the ends of those router bits so they don't fall down into the head as you adjust the play :) I can't say that my throttle bodies are synched perfect-perfect, but they were improved from where they came from the factory, and it helped with the hanging idle. I have the full AKRA, but stock airbox. I hope you get it sorted, keep us posted.

User avatar
nrvous
250cc
250cc
Posts: 67
Joined: Tue Mar 29, 2011 2:47 pm
Country: Estonia
City: Tallinn
Year: 2018
Colour: White

Re: Throttle body adjustment gone bad. Save my summer!

Post by nrvous » Mon Aug 05, 2019 11:13 am

slowdown wrote:
Tue Jul 30, 2019 2:49 am
'm always breaking stuff on my bike, and I probably shouldn't try to work on it, but I continue to do so.

I have a '14 1290R, almost 28,000 miles. I absolutely love it. Best bike I've ever owned. I ride the piss out of it. It's my favorite thing to do. I'm really hoping I didn't kill it.

Some time in the past 10k miles or so I started noticing that my idle was hanging for a few seconds around 2250 RPM when I let off the throttle. A quick throttle blip will also make it hang for a couple seconds. After a couple seconds it would drop to 1400, which is the appropriate idle RPM. Very rarely when I'm riding I'll let off the throttle and expect some engine braking to occur as it normally does only to be surprised that the bike keeps sailing at current RPM for a second or so before starting to compression brake. It almost feels like the bike is floating. Kind of strange.

I read some threads on various sites and found this to be a relatively common issue, especially for people with the mods that I have done (Rottweiler airbox, de-cat, cannister/SAS removal, PCV, Remus midpipe and Remus can). I read a bunch of people saying that balancing the throttle bodies will fix the issue. I found a long thread on superduke.net where a bunch of guys had luck bench syncing their throttle bodies.

So I tried it, and now my bike runs like complete shit.

I took off the tank and airbox to have access to the throttle bodies and the adjuster screw.

I pushed the linkage arm so that the valves were wide open (using the throttle with the bike on but not running will only move the valves 1/4 open max), and measured the distance that the front valve was open versus the rear. I adjusted the rear to try to bring its measurement closer to that of the front. The front is not adjustable. I didn't know if turning the screw clockwise would bring them closer to the same measurement, or if I needed to go counterclockwise. So I tried both and re-measured several times.


In the end this resulted in two full turns of the screw clockwise, which seemed a lot (the screw has yellow paint on it, so it's easy to know when a full revolution has occurred). The measurements had come closer together, so I put everything back together, started it up, and IT RAN LIKE SHIT. The bike was visibly shaking/juddering, it idled lower than it should, and it had this terrible resonating sound, so I killed it. I backed the screw off 1 turn and tried again, and it was still shitty, but not as bad. I decided this was no good, so I tried to put the screw back the same position it was before I started.

I put it back to where I believe is the original position, but the bike still runs worse than before. The hanging idle is gone, but the bike is running badly, and I'm not sure what to do with it. I let it idle for 10 minutes (fabled 10 min reset), and it ran a little better when warm, but on my commute today it ran like $HIT all the way home.


Symptoms:
Idle RPM seems to drop to 1250 sometimes coming back to 1400
Engine is stumbling through 1250-3000 RPM in first gear, much worse than it ever has
Engine wants to stall when taking off out of first gear (nearly dumped me today making a left turn from a stop when it abruptly stalled halfway through the turn)
Engine will occasionally stall when giving a quick throttle blip in neutral
Strong smell of gasoline when coming to a stop
Intermittent shaking/juddering
Questionable ticking sound when engine is running
Just doesn't feel right.


If all I did was turn a single screw, and then put it back to its original position, why am I having all these issues? I guess its possible that I miscounted the number of revolutions and the screw is +1 or -1 from its original position, but I don't think that is the case.

Would hooking up a vacuum gauge to the bike and balancing that way help? I'd love to do that, but I can't figure out how to get access to the adjuster screw while the bike is running (tank/airbox are in the way) in order to make adjustments in real time. I also read somewhere that KTM says the throttle bodies on these bikes can't/shouldn't be mechanically adjusted (then why is there an adjuster screw?). I don't know why that would be the case, but I read it in a couple places.



Here's some pics/vids
Valves (little dirty right?)Image

Adjuster screw
Image

Valve wide open
Image

Throttle body motion with engine off:
https://www.youtube.com/watch?v=7KXvyHV ... e=youtu.be

Engine idle, ticking sound:

https://www.youtube.com/watch?v=T-xz4MU ... e=youtu.be


Usually throttle bodies are adjusted when the bike is running:

Image
Image

Rottweiler Performance - Remote Fuel Tank Kit for Throttle Body Balancing

Post Reply