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Old 10-15-2012, 04:22 PM   #1
anitasanger OP
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R1200GS flywheel effect?

Hey guys. Been considering a big GS for a while now. I'm currently riding a 1200 sportster. I rode my dad's 2009 GS yesterday and couldn't help but notice a somewhat tiresome intense engine breaking anytime I let off the throttle. On my Sportster, I can let off at highway speeds and barely even notice a braking effect, it doesn't even throw me forward in the slightest. I'm assuming that the effect is caused by the GS having a really light flywheel, resulting in quicker revs? Is this the case? Anyway, I'm wondering if any of you GS owners coming from a Harley, or any other heavy-flywheeled bikes had to get used to the heavy engine braking/diving upon letting off off of the throttle? I'm sure it's something I could get used too pretty quickly.

Thanks,
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Old 10-15-2012, 04:48 PM   #2
bobbybob
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1) Harleys have a belt drive which mutes a lot of the "suddeness" of deceleration vs the shaft drive.

2) Harley's have lower compression ratios which also decrease engine braking.

3) yes you will get used to it and in fact will learn to use it to your advantage!
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Old 10-15-2012, 04:58 PM   #3
def
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Quote:
Originally Posted by anitasanger View Post
Hey guys. Been considering a big GS for a while now. I'm currently riding a 1200 sportster. I rode my dad's 2009 GS yesterday and couldn't help but notice a somewhat tiresome intense engine breaking anytime I let off the throttle. On my Sportster, I can let off at highway speeds and barely even notice a braking effect, it doesn't even throw me forward in the slightest. I'm assuming that the effect is caused by the GS having a really light flywheel, resulting in quicker revs? Is this the case? Anyway, I'm wondering if any of you GS owners coming from a Harley, or any other heavy-flywheeled bikes had to get used to the heavy engine braking/diving upon letting off off of the throttle? I'm sure it's something I could get used too pretty quickly.

Thanks,
Bobbybob is correct..........Also, bore to stroke ratios, gear ratios, motorcycle weight....there are many factors that come into play when you let off the gas.

But, you say you could get used to it quickly? If so, why are you whinin' about it? The Harley is like a tractor, lots of torque and a somewhat low tech V-2 engine that takes a while to drop RPM...if you do switch to the boxer, you'll notice many other BMW attributes, too many to mention here.

(1200 Sportster? You have my sympathy).
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Old 10-15-2012, 05:08 PM   #4
bobbybob
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Yeah and I just compared compression ratios on a 1200 sportster vs the GS: 9.7 vs. 12.5 . Thats a *huge* difference. Fine tune your throttle hand and use that engine braking to your advantage!!
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Old 10-15-2012, 05:11 PM   #5
lkchris
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Don't know enough about Harley models to immediately understand the age of the one under discussion, but the BMW for sure has fuel injection, which completely cuts off engine fueling on decelleration--something impossible (at least never done) with carbs. Something BMW riders get used to moving on from Airheads.
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Old 10-15-2012, 05:51 PM   #6
Tebpac
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You'll learn to love it. Especially in the twisties....
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Old 10-15-2012, 06:14 PM   #7
anitasanger OP
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I wasn't whining about anything, merely wondering the scientific reasons for the effect. Thank you for the explanations bobbybob.

I have an 09XL1200N with a handful of unrestricted performance mods. I do love the bike in a primal, pure motorcycle experience kind of way. It's loud, handles great, pulls like a freight train, and looks classic. On the other hand, it has the worst suspension ever put on a motorcycle, the seat feels like concrete, no wind protection, no gear-hauling capabilities, etc.

I just got back from a multi-state ride from Oklahoma to Colorado, and in turn - decided to retire it to 200 mile radius from my house bike. For those of you who've ridden 412 in the Oklahoma panhandle - you know it's a pretty rough road with big, black expansion joints every 5 feet. On my bike, it feels like your deuce hole is being pounded with a rubber mallet 50 times a minute. I have a few couple thousand mile trips on this bike under my belt, but those days are over.

I've always wanted an ADV bike, primarily a GS. The wife has given me the green light to get one in about 2 years. So it's looking like I'll be getting a non-beta version of the new gen GS. I test rode my dad's yesterday and really loved it. The Sporty seemed to have a bit more low/mid range punch, then again, the performance mods really woke my bike up.

I want heated grips, a nice seat, wind protection, giant panniers, and electric cruise baby! I'm finished being tough, this creature wants comfort. I'm so tired of taking an hour to put everything in stuff sacks an then jam it all into my motofizz camping bag! Does anyone else's gear seem to expand with each passing mile? :)

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Old 10-15-2012, 07:42 PM   #8
Wolfgang55
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The FI on the BMW is much better set over the HDs. Meaning CC against CC the HD puts out much less in a stock form.

You learn to love what the GS can do for you, soon as you learn the strengths of its differences.
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Old 10-15-2012, 07:57 PM   #9
anitasanger OP
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Excellent! I think it's time for a more refined kind of ride. I couldn't believe how smooth the beemer's gearbox was. The up shifts were so quiet and smooth, I cold barely even feel the exchange.
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Old 10-15-2012, 08:23 PM   #10
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No attempt at anything scientific here, just a couple observations. For a long time I rode Triumph triples, 955's and a 1050 (you can throw in an FJR because it did the same thing I'm about to describe). When riding in multi-bike outings I would from time to time get stuck behind various variations on HD sportsters. I hated it because I would always wind up crowding them through corners because they scrubbed speed way more than the Triumphs or even the FJR. It wasn't a Ricky Racer kind of thing. I would try to keep a matching speed going in, but wound up right off their fender. I was told by the HD folks that was because of engine braking or flywheel effect. When I rode my Tiger 1050, I had to work to keep up with GS's, that's why I got one.
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Old 10-15-2012, 09:00 PM   #11
BaddAndy
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Keep your HD for around town riding in traffic. The GS sucks in this enviroment. I now rue over not keeping my Bandit for riding to work.
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Old 10-15-2012, 09:45 PM   #12
anitasanger OP
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Thanks for all the input guys, very helpful! I think I'll be happy with a new water head GS as my camping:touring bike, and keeping the sportster as a runabout, back road blaster. :)
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Old 10-15-2012, 09:56 PM   #13
texzen
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Your on the right track....I've had 6 Harley's, 2 Goldwings, and 3 GS/GSA's and the GS's IMHO are the best overall touring/exploring bike made.
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Old 10-15-2012, 10:13 PM   #14
def
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Quote:
Originally Posted by anitasanger View Post
Thanks for all the input guys, very helpful! I think I'll be happy with a new water head GS as my camping:touring bike, and keeping the sportster as a runabout, back road blaster. :)
The GS will never make those raucus engine sounds Harley's are famous for, the boxer engine is difficult to hot rod, there's very little chrome on the GS but brakes, suspension and electrics are first class (if you can get over CANbus).

I've always admired H-Ds approach to curbing engine detonation however. I believe they use a Delphi ECU which contains a spark gap ionization feature to detect detonation...very clever and no knock sensor needed.

Good luck with your wethead. Hope you'll forgive my earlier crassness.
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Old 10-15-2012, 10:17 PM   #15
trc.rhubarb
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Takes nothing to get used to but now i have boot marks on my pipes from putting my feet too far back

GSA is easier to ride in almost any condition even though I can only get one toe down unless i lean or shift off the saddle to get a whole foot down.

My HD is as fast if not faster than the BMW until the motor hits its sweetspot somewhere around 4600rpm... then it's all over. Around town, the HD is faster light to light but can't point its front tire at the sky either
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