Hi All,
1985 K100RS
Bike starts ok hot or cold but idle very lumpy when cold.
Opening throttle from cold, engine stutters and usually stops about 1200 rpm, coaxing temp up, can drive bike when warm. Acceleration is good but VERY slight misfire can be felt occasionally on steady cruise condition.
Have done the following.
Replaced Hall Effect Triggers         Replaced injector relay
Replaced fuel pump                     Replaced fuel pressure regulator (twice)
Replaced fuel filter                      Replaced crankcase vent hose
Replaced water temp sensor         Replaced filters & pintle caps on injectors
Checked injectors on 9 volt           Checked fuel pressure - approx  35psi at rail - pump blows off about 70psi
Connected HT strobe & LED on injectors & run engine to try and see if either misses some pulses - all look ok.
One final "pointer"
If when throttling up expecting engine to cut, I momentarily pinch the fuel hose leading to fuel regulator the engine picks up perfectly??? 
I believe ignition is ok
Could it be EFI sending wrong pulse duration to injectors??
I am at wits end - any suggestions gratefully accepted.
Wingless

What about spark plugs and wires?  I had similar symptoms and it turned out to be a plug wire not fully cliced on to a plug.  Missed a bit off idle but once the plug was hot it ran fine.

Cheers.

I had a similar problem with the LT some time back. Wasn't long after a service. One of the new plugs was the problem. Which also makes me wonder
what plugs and leads are you running? If the leads are originals then non resistor plugs. Just making sure yours is 8 valve engine.

K.R. /Olaf

Two good points -  Plugs are nd always have been NGK 7AE, ie non resistors.

If the weather is o.k. tomorrow, ( bike lives outdoors and I'm an arthritic wimp ),  I'll put the old ones back in as I know they were good anyway - only changed them as a matter of habit, and ensure caps are properly located. 
Will advise outcome. 
Wingless

Result:
Plugs, caps & coils o.k.
Checked air flow meter & temp sensor per Crazy Frog's check list - o.k.
Fitted a different (used) EFI unit. Slightly better.
Tweeked CO adjustment 1/2 turn ACW  - no means of measuring but idle sweeter. Went for a 20 mile run & everything seemed perfect. Reduced idle speed on return. Have not had opportunity to try a cold start again.
If everything fine will try the old EFI again - just for curiosity.