low rev sluggishness

[garr2]

I have an annoying miss/sluggishness at about 1500 rpm before they motor has warmed up.
I have done a TB synch and replaced the plugs (primary & secondary) and stick coils.
I'm probably being a bit anal even worrying about it - but having said that, what should I try next?

[MoonBeemer]

I have the exact same problem. So I hope someone has some ideas. Additionally, I have checked for leaks around my TBs.

[gregor]

I know its not helpful , but I never attempt to ride the bike at such low revs which I consider barely above idle. Even my very torquey diesel turbo car needs to be kept at 2000rpm plus before it pulls smoothly and strongly . The analogy may not be helpful for those across the pond.

[sweatmark]

I have an annoying miss/sluggishness at about 1500 rpm before they motor has warmed up.

Seems to be one unfortunate characteristic of oilheads. Experienced the same off-idle hiccup when cold (or warm) with all the BMW Roadsters we've owned: R850R, R1100R, R1150R, and Rockster. Aside from dead start in 1st gear, it's not a part of the performance envelope that's encountered in regular riding, so I don't worry about it despite the annoyance. Considering the tall 1st gear these bikes have, a few extra RPMs and momentary clutch slip deals with the situation.

Note that our former R1200C had no problem with grunt in this RPM range; its intake tract tuning was obviously different.

[CycleRob]

If it only does it before it's warmed up, that's almost normal. My OilHead, in cold weather, would sometimes flame out trying to take off from the stop sign 0.2 mile away from the house. Solved it by leaving the low idle lever "on" until after 2 miles or so. It's just a lean fuel map, likely improperly programmed for those cold engine temperatures. It's Motronic2 engine management system is very primitive. So primitive that both fuel injector nozzles and both sparkplugs fire at the same time, every 360 deg turn of the crankshaft. Yes, it squirts fuel even when one cylinder's intake valve is closed!! Is it any wonder that there's a running problem?

My F800ST has absolutely none of those annoying and potentially dangerous stalls, in traffic or otherwise. It runs the way you'd expect modern day EFI to work after decades of development. Perfect. Never a surge, stall or misfire . . . . at any engine or ambient outside temperature.

[gregor]

Went out on the bike today and thought of this matter. I only visit 1500rpm while pulling away from a standstill. No problems at all. Otherwise 2500/3000 plus rpm to keep things on the boil.

[ciscoe]

Mine isn't so much happening at that RPM but when held at a constant rate. I could be cruising at 30mph and feel random slight hesitations. I first felt it in the Fall and wrote it off to a tune up. Well, it didn't go away. I changed plugs, fuel filter, air...

Any idea is welcomed.

[Seamripper]

You always gotta keep the revs up with the oilheads. Lugging these engines at low revs can cause damage. They seem to much prefer the 3000+ range.

Yes, this seems strange with a twin and it took me some time getting used to.

[psychodeathbot]

I recently corrected some mild surging and idle problems by doing the following: Resetting the Motronic, properly adjusting the valves (technique is important here, I'd suggesting checking out http://largiader.com/), removing a Techlusion 1031 installed by a PO, and removing the charcoal canister and correctly routing the tank drain vents (the PO looped them together for some dumb reason). I still have to do a TB sync to smooth out some vibration, but low-end throttle response, MPG and idle speed are noticeably better.

[gregor]

Cyclerob,
Interesting. Can't think of a problem with both plugs firing together though, if the ignition timing is truly the same on both cylinders. My old Triumph had two sets of points so that the timing could be set individually on each cylinder. And it needed to be set that way- not quite a 180°parallel twin.

But the fuel being injected while the valves are shut sounds odd- are you sure about that? Surely the misdirected fuel would trickle into the cylinder eventually along with the properly atomized stuff and cause mayhem with the mixture?

[sweatmark]

I recently corrected some mild surging and idle problems by doing the following: ...removing a Techlusion 1031 installed by a PO... low-end throttle response, MPG and idle speed are noticeably better.

That's interesting. I would like to try the opposite - a Techlusion or Booster Plug to enrich mixture in conjunction with aftermarket exhaust currently installed... have read reports of R1150** bikes becoming smoother with the added fuel, so it's curious to read your account of smooth running gained via leaner mixture under some conditions.

[Boxer]

hee hee hee....gregor asked Cyclerob if he was "sure about that?"

[psychodeathbot]

To make things more convoluted, it seems that each bike is unique. Tuning works for some, but not others...some are more vibey, etc. That seems to be the consensus over on the IBMWR tech list, at any rate. My goal was to return it to stock (or as close as possible), do some really careful tuning following spec, and go from there. As it turns out, I don't really need to do anything else aside from the TB sync. The Techlusion may or may not have been the culprit and in fact, I suspect tuning alone (esp resetting the Motronic) would've fixed it, but I don't have any evidence. In my case it certainly isn't necessary, didn't really seem to do much for performance, and personally I'll take the MPG boost over HP.