Hi all

I just made a rebuild of a K100 to Cafe racer.
Added a M unit blue and new controls and speedometer.
Removed original Airfilter box, and mounted Airflow meter directly to inlet. 
Added a Lunch Box remover unit from Joost.

It started immediately. But running insane high RPM. Around 4000+ can't measure it, since I need to shut it down fast.

I have looked at my wiring, and can't see any error. 

The bike ran ok before I took it apart, but with broken breather hoses etc. So not in good condition, and not sure what previous owner has done.

The wires are replaced to M-unit (light, instruments, buttons etc), but for FICU and ignition it is the original. 

I have tried to:
- bypass the Throttle Butterfly Switch with 12V to the white/black wire, to simulate idle. No change.
- Disconnect the Air Flow meter, then it won't start at all.
- Check that I have +12V at the Throttle Butterfly Switch, ok. 
- Check for clearance in the gas cable. Ok.
- Checked resistance in water temp. sensor. Seems a bit low, around 1,9 K-Ohm, but should this increase RPM to 4000+ ?
- Checked for mechanical air leak. 

The Fuel Injection Control Unit is getting RPM information from Ignition Trigger Assembles, as far as I can see in the diagram. This connection is the original. So I don't think the FICU sees a wrong RPM, or am I missing something ?

Checked the hose connections from tank to rail and Fuel pressure regulator, seems correct. 

The vacuum switch is still there, but wires disconnected. Will this cause this issue ?

Is there any electrical issue, that can cause the FICU to increase the RPM so much ?

Have you completely disconnected the throttle cable from the throttle body assembly then started the engine?

Yes just did, no change. Still extreme idle

Laitch wrote:Have you completely disconnected the throttle cable from the throttle body assembly then started the engine?

Yes, same issue.
Measured all connections between airflowmeter, ecu and ignition unit. All ok.

Have you viewed the position of the valves within the throttle bodies with an inspection mirror?

Laitch wrote:Have you viewed the position of the valves within the throttle bodies with an inspection mirror?

Problem solved. Mechanical block of throttle, so not going all way back to idle mode. Thank you

That's good news, Stefan! Can you be specific about what was interfering? A lot of us are just sitting in the shade today waiting for excitement like this to inspire us.

Laitch wrote:That's good news, Stefan! Can you be specific about what was interfering? A lot of us are just sitting in the shade today waiting for excitement like this to inspire us.

  yes sure, one of the belts holding the rubber inlet needed to be turned a couple of centimetres, to allow the throttle fall back to idle position. So small fix to a big headache

right Stefan
you've already found the reason
the hose clamp just above the inlet can get in the way preveting the butterflies to close all the way