@cliffa and
@Clive from my perspective, I'm still pretty new to 961's but not to working on cars and bikes.
When I got mine late last year, it idled and started really inconsistently, did the up and down to 2k when hot and, as I mentioned, just died when you'd pull the clutch in at the lights. I did the normal things, sprayed carby cleaner around all the obvious points when trying to diagnose it, blocked the IAC (on the throttle side and the airbox side), changed plugs coils leads etc.
The worst thing was that I felt, as much as so much advice is good, there was a lot of anecdotal or non evidence based changes being made to improve things. I was only every guessing.
After reading alot, the symptoms were so in common with what
@iwilson described in his threads, that I couldn't really ignore it. The reality is, the EFI system is a temperature sensor, a crank and cam position sensor, a TPS and o2 sensors. The ECU can only take values from those and output to the coil, injectors and the IAC. It's when to spark, when and how long to spray fuel, and add some air for idle control.
The balance pipe mechanically interferes with the outcome the ECU is adjusting the injectors to achieve. The ECU says put fuel here, and the balance pipe (combined with 270' engine design) makes it go there. When you hook up the cable to the ECU you can watch it happen on the laptop. Yes, sensors do fail, there's no doubt. But the system simply isn't complex enough that it can't be made consistent. and blindly "guessing" which or if one is the problems has cost a lot of owners, money, time and heartache.
Since blocking the balance pipe (and before the installation of the delta) the startup, idle and low end/just off idle performance of the is significantly better. I don't need to "ride around" the bottom end like I used too, holding a bit of throttle and juggling the brake so it doesn't stall at clutch in or have it foul a plug into uselessness in traffic. It's consistent and predictable.
