R1200S Wont rev up from tickover.

[DPG]

I'm having a problem that I've not seen before and I’m hoping that someone here has seen it all before and will tell me about it.

I have a 40K mile 2006 R1200S thats new-to-me and it wont lift up from idle. If you just crack the throttle a little it's coughs, sputters and, if held too long, stalls out. If you snap it hard open it just stalls. Horribly. You *can* gently 'bounce' it a thousand rpm or so but it doesn't like that at all and ultimately stalls. And it sounds horrible. Only did that once. Tickover itself seems ok. A little noisier now that I've relaxed the valve clearances (more on that later) but not concerning at all. Starting is about normal too. Every one of these engines I've had takes at least 2 full turns to get it started and this one is about the same. Click, spin, spin, start. Maybe 3 turns when its cold but no more. Starts every time.

Now, when I bought it, it was running ok although *very* quiet on cold start (too quiet) and slow to rev when you crack the throttle but overall a working bike with some miles/maintenance issues that I am sorting out one by one before taking it to the track.

One of those problems was a leaking exhaust header on the off-side due to corroded acorn nuts which needed some machining to replace the studs and that needed the head to come off. So the RHS head had been off, the valve train apart and everything put back together again. Just like I've done a dozen times on the BoxerCup and at least 3 times on previous Hexhead GS's. But this time something's gone wonky and I don't really know what.

I've checked:
- Throttle cables. I didn’t remove the throttle body when I took the head off but I checked the throttle cables anyhow as I learned that lesson on my first R1100GS years ago. Both TB cables are seated at the splitter end and at the TB. All looks (and feels) good. The cable balance is even pretty good too - I hadn’t got around to interfering with that yet.
- Balance servos. They make encouraging noises the you turn the ignition on (sounds very much like a full range test before centering) and if you unplug either of them on at tickover, the engine goes grumpy and stalls. So I assume they are working just fine.
- Fuel. It had no fuel in it at all when I picked it up so I've its has new, clean fuel in it, no change. I cant vouch for the filter though. It is something I need to check anyhow.
- Coils /Spark Plugs. All four coils and plugs are ok with a good spark clearly visible. Tickover alters slightly if you unplug LHS main coil feed as you would expect but pulling the RHS main coil feed makes no difference even though both mains have tested ok and have good spark.
- Both injectors. If you unplug either while its ticking over, it dies as expected.
- Clutch Switch. I read that the clutch switch can cause problems (but don’t really understand why) but I swapped the brake and clutch switches over anyway and its still the same. Noted that tickover rises smoothly to 2200rpm when clutch pulled in. But still wont rev from there.
- Valve clearances. The valve clearances were very, very tight indeed when I first got it on the ramp. Along the lines of .05mm intake and .15mm exhaust with the rockershafts having no endplay at all. That nicely explains why it was so lovely and quiet on start but as I intend long runs at the track, I couldn't leave them like that - I'd be worried about heat expansion locking everything up so I've set both sides back to .15mm intake and .30mm exhaust with the rockershafts having .50mm endplay. I’ve not looked up the spec for the R12S specifically but I assume it would be the same as all the other Hexheads?
- Sensors/Electrical. I have no way of telling if the Cylinder Head Temperature sensor, the Cylinder Knock sensor or the O2 sensor are ok. the best I can do in the first instance is double check that I had them all plugged in the right way. So I checked them (about a dozen times) and they are. I cant read the ODBC info at home as I don’t have the gear so finding a lead and error-reading software for the laptop is tonight tasks after I’ve finished posting here.


I’d really appreciate any helpful thoughts, comments, idea’s?

[nab 301]

Now, when I bought it, it was running ok although *very* quiet on cold start (too quiet) and slow to rev when you crack the throttle but overall a working bike with some miles/maintenance issues that I am sorting out one by one before taking it to the track.

One of those problems was a leaking exhaust header on the off-side due to corroded acorn nuts which needed some machining to replace the studs and that needed the head to come off. So the RHS head had been off, the valve train apart and everything put back together again. Just like I've done a dozen times on the BoxerCup and at least 3 times on previous Hexhead GS's. But this time something's gone wonky and I don't really know what.

I’d really appreciate any helpful thoughts, comments, idea’s?

I've no hexhead experience and I've never really had any major mechanical problems on my high mileage 11S apart from replacing a camshaft so the only advice i can offer is of the basic variety ... Check compression and recheck valve timing ? If only to eliminate the possibility.
The revs changing when you pull the clutch is strange but the only advice i can offer on that comes from old car engines and was related to too much crankshaft end float .

[DPG]

Thank you for your comments everyone.
I think I’m making some progress. In a moment of clarity (and I’m sure someone suggested it) I checked the TPS reset procedure and I had it all wrong. So one TPS reset later and it was running smoothly. For about 15 seconds. And then the problem returned. I reset the TPS again and the same thing happened again so the TPS looks suspect. On top of that, with the TPS disconnected completely, the problem is exactly the same so it lends credence that the TPS is buggered. Also i found that with the TPS disconnected and the clutch pulled in, it will rev much more nicely and smoothly from idle. Its not fixed as such but much better and that just increases my confidence that the TPS is at fault. I’ve ordered on from Motorworks to replace it and we’ll see.

My only other wonder for now (and I’ve not taken the old one off yet) is how to adjust/calibrate the physical position of the replacement when I get it on there? I know the r1100s need to be tweaked to about 3.8v on that end pin, are the newer ones the same?