Engine Braking

[Edmund Kean]

This one's for the experts

Rode a mate's new to him GS yesterday and noticed his bike possesses noticeably more engine braking than mine. Both bikes have similar mileage at about 6K miles on the clocks; any reason for the difference? Mine is fully specified from new; did BMW do some bikes with slipper clutches maybe? Both bikes are 2011 DOHC.

Ed

 

[Whele]

At what rev range are you referring to with regard to engine breaking? The slipper clutch should only make a difference at high revs where there is a potential for the rear wheel to lock up, lower down in the rev range there should be no slippage.

 

[Bendy toy]

Slipper clutch is only to stop rear wheel locking on aggressive downshifts. It wont move the clutch plates in normal use.

Maybe your mate's engine was mollycoddled from new and now has tight piston ring / cylinder clearance. These bikes need to be used with a firm hand from day one. Not thrashed or slogged but otherwise worked well. Driving about gently will polish the bores before the rings have properly bedded in making the engine tight.

The fix is to run the bike hard on some long runs but it could take a few thousand miles to properly free off.

 

[Popell]

Can't see the small difference in ring/bore sealing being anywhere like large enough to be noticeable on engine braking (you'd be blowing oil all over the place if it was)
I reckon your brakes are binding or pushing back less, try centre stand and spinning wheels.












your fd could be shagged too!

 

[Edmund Kean]

At what rev range are you referring to with regard to engine breaking? The slipper clutch should only make a difference at high revs where there is a potential for the rear wheel to lock up, lower down in the rev range there should be no slippage.

Riding country B roads most of my time on the bike, I mainly use 2nd, 3rd & 4th keeping revs between 4.5 - 7K.

Ed

 

[Edmund Kean]

Can't see the small difference in ring/bore sealing being anywhere like large enough to be noticeable on engine braking (you'd be blowing oil all over the place if it was)
I reckon your brakes are binding or pushing back less, try centre stand and spinning wheels.












your fd could be shagged too!

Fortunate then it's not my bike - shouldn't think I'll pass that on

 

[KMD]

You could always do a cylinder compression test on both bikes, I'd assume the bike with the higher cylinder compression would have the stronger engine braking.

 

[autogs]

no slipper clutch on the hexhead!,its in your head were you in exactly the same gear same revs same gradient of road etc

 

[Pukmeister]

It depends on the fuel map in use, throttle butterfly angle etc etc blah blah blah.

No two bikes are indentical, and engine management is individual and based upon many variables.

 

[Alan R]

It depends on the fuel map in use, throttle butterfly angle etc etc blah blah blah.

No two bikes are indentical, and engine management is individual and based upon many variables.

interestingly, or at least I thought it interesting, when I had my 1200 remapped at hilltop, I felt that the bike was noticeably smoother and less on/off throttle. I noticed that throttle roll off seemed to more gentle ie less engine braking. In my mind this is a result of Geoff sorting out the standard weak mixture which before remap provided just enough power to maintain a constant cruise state: close the throttle slightly and instant starvation and dramatic reduction in power. All this is probably fancyful wishful thinking/nonsense, but the effect is real whatever the cause.
Alan R

 

[Edmund Kean]

It depends on the fuel map in use, throttle butterfly angle etc etc blah blah blah.

No two bikes are indentical, and engine management is individual and based upon many variables.

Had I thought more about my original post, I should have made reference to this; when I returned to my bike I dipped the clutch a couple of times just to check the bike was fully off throttle. Pukmeister & Alan R could be close to explaining a reason for my experiences then. It may sound odd but I quite liked the more dramatic engine braking on my mates bike particularly so on roll off approaching a bend.

 

[JerseyNeil]

My mate and I both have 2010 TC GS' his has had the Ecu remapped at hilltop. When I rode it i noted that his had less engine breaking than mine. That said I never rode it before it was remapped so I might be talking b*llocks.

My bike was ridden too sympathetically by its first owner (it had 1,500 miles on it when I bought it) and I have now done 13,000 and it still burns oil. That said I love it and would not swap it.

Neil

 

[Edmund Kean]

My mate and I both have 2010 TC GS' his has had the Ecu remapped at hilltop. When I rode it i noted that his had less engine breaking than mine. That said I never rode it before it was remapped so I might be talking b*llocks.

My bike was ridden too sympathetically by its first owner (it had 1,500 miles on it when I bought it) and I have now done 13,000 and it still burns oil. That said I love it and would not swap it.

Neil

I suppose the best way I could describe the difference is mine rode like the "choke" was slightly out in comparison to my mates.

 

[JerseyNeil]

Strange. That is not what a hilltop tuned bike felt like. Maybe something is sticking slightly. It could be the dubery or the whatchamacallit (I'm not master technician).

 

[Bendy toy]

My 08 bike had 33K when I bought it back in December 2012 and was well settled in. It now has 52K. The FD has been rebuilt at 50K but it burns no oil regardless of slow town/short runs or long thrash rides. When the back brake began to bind I noticed zero difference in fuel consumption or anything else. The only clue was the hotter than normal rear disc. A caliper build sorted it.

My brother's bike also an 08 Adventure was spotless when he bought it with 10K miles FSH, blah, blah and far too many farkles. His fuel consumption was similar to mine but the bike burnt oil and always felt like the brakes were rubbing. It now has 25K. The engine feels much more like mine and hardly burns any oil.

The original owner used it almost exclusively for two up holiday tours with low seat, forward pegs and such. That was his choice of course but the result was a tight engine. The other result was his gearbox is slicker shifting than mine with less transmission backlash. So maybe the gentle treatment suits the transmission. We can't have it all ways.

 

[Mistacat]

You could log both bikes with a GS911 and study the data.

If the TPS is not showing 0 (zero) on closed throttle you would loose a lot of engine braking.

On deceleration at most rpm the injector pulse width drops to 1.3 Ms compared to 2.0 Ms on hot idle. ( an AFR leaner than 22 to 1, that's as lean as I can measure)

Also the Idle actuator steps drop from around 114 on hot idle down to around 85 steps as soon as the TPS comes of zero and I have recorded as low as 35 steps on deceleration.
These settings provide excellent engine braking.

The clutch switch does have an effect and a faulty one can be the cause of stalling during deceleration along with secondary coils etc etc. going off topic.

 

[Steptoe]

You could log both bikes with a GS911 and study the data.

If the TPS is not showing 0 (zero) on closed throttle you would loose a lot of engine braking.

On deceleration at most rpm the injector pulse width drops to 1.3 Ms compared to 2.0 Ms on hot idle. ( an AFR leaner than 22 to 1, that's as lean as I can measure)

Also the Idle actuator steps drop from around 114 on hot idle down to around 85 steps as soon as the TPS comes of zero and I have recorded as low as 35 steps on deceleration.
These settings provide excellent engine braking.

The clutch switch does have an effect and a faulty one can be the cause of stalling during deceleration along with secondary coils etc etc. going off topic.

At last some sense in a sea of shite .

 

[Bendy toy]

So how do you explain the low miles bike with tight engine v normal miles bike with free spinning engine?

I also had the same issue with a Fiat Seicento. Having been used all its life around town, it was slower than a slow thing on faster roads. Two months of motorways commutes transformed the "performance". 40bhp was never going to burn much rubber.

 

[Steptoe]

So how do you explain the low miles bike with tight engine v normal miles bike with free spinning engine?

I also had the same issue with a Fiat Seicento. Having been used all its life around town, it was slower than a slow thing on faster roads. Two months of motorways commutes transformed the "performance". 40bhp was never going to burn much rubber.

Who knows and who really cares

 

[wildoat]

My mate and I both have 2010 TC GS' his has had the Ecu remapped at hilltop. When I rode it i noted that his had less engine breaking than mine. That said I never rode it before it was remapped so I might be talking b*llocks.

My bike was ridden too sympathetically by its first owner (it had 1,500 miles on it when I bought it) and I have now done 13,000 and it still burns oil. That said I love it and would not swap it.

Neil

Just as a note of interest, I had two R110gs's both from new. they both stopped using oil completely between 13,000 and 16,000 miles, after that they performed brilliantly and my oil bill dropped to virtually nothing!