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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Oliver on August 25, 2013, 01:24:12 AM
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Im just curious because anytime I hear someone say they can get a k75 to 120 I call bullshit, basically Im worried if my bike is messed up because when pushing my bike as hard as I feel comfortable doing I can get to 90, not saying it cant do more but it scares the shit out of me thinking its bad for my engine. Im not scared of going fast just worried about my bike. It may come from taking my Honda cb350 on the highway praying when I had to but I just want to know If I should be looking for a way to give my bike some more power. Running all stock rt wishing to do the ton comfortably. Please give me a reality check. ha
Cheers
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The engine is the last thing I worry about, deer and tickets much more of a problem around here. If you want more speed loose that barndoor RT fairing, it's a little much for a k75 to push through the air.
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Like Chaos - I'm not worried about engine at all but my driving license... (maximum speed limit here is 75 mph / 120 km/h)
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These engines (100's too) will run close to the rev-limiter all day long. The higher you rev them, the more power they make.
That being said, I do notice a significant mileage drop off around 80 mph. That, coupled with the risk of having to converse with law enforcement, 70+ is the maximum I prefer to run. But, it has nothing to do with the capabilities of the engine.
Tom
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Ill be ripping that fairing off with in the next few weeks. On the highway here its pretty normal to be running 85+ I think after 90 you might get pulled over. That being said when im up at 85 im around 5500 to 6000 rpms and it just sounds like its really working, so if you say thats what the engine likes then okay you have put my mind at ease. Also I feel the power band really sags around that area, so 120 sounds ridiculous to me. Thanks for the info, keep the polls coming
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My bike seems to like cruising in the 70-90 range. I try to keep her in the low 70's, cuz of LEO but 80+ comes easy. Never been much over 100 on this bike and it felt like I could run there for hours.
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Speedometers on these K's are notorious for being WAY off. Usually reading high. My bike is 6-7% off. Easy to correct but unless Duck had it (highly likely on the west coast) it's probably off.
Search speedometer correction and you should find a couple posts on how to true it up.
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I have got my 'naked' k up to 110ish on the speedo. I was tucked in and pretty much stripped. While cruising and loaded 80ish is enough. I bet the fairing is the biggest impediment.
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Speedometers on these K's are notorious for being WAY off. Usually reading high. My bike is 6-7% off. Easy to correct but unless Duck had it (highly likely on the west coast) it's probably off.
Search speedometer correction and you should find a couple posts on how to true it up.
Before I corrected mine, I would be doing an indicated 70, and get passed like crazy. I think it was like easily 10% off, to the high side. Now it's a bit fast at 65, by 1 or 2 mph verified by GPS.
To answer the question mine just settles in really nice at an indicated 70, and I've had it up around 90-100.
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Ya my speedo runs 3-5 mph high. Theoretically it helps me not get tickets...though i just got a 20 over!! i use my gps if I really need to know.
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Speedometers on these K's are notorious for being WAY off. Usually reading high. My bike is 6-7% off. Easy to correct but unless Duck had it (highly likely on the west coast) it's probably off.
Search speedometer correction and you should find a couple posts on how to true it up.
Really? I've been lucky then, my speedometer shows almost exactly same speed as my gps. Max 1 km/h difference. Maybe it's because this was an ex-police-bike?
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I am no speed demon usually sitting at around 4mph over my calculated estimated speed in regards to speed limit, but my daily commute offers a truly stunning opportunity to let it all out headed home after a stressful restaurant job. I cross the scenic Cumberland River enjoy a well banked turn and out in front of me is 7 straight miles of good pavement with a big concrete center divide and not a single hiding spot for the police. Without the side bags on and in a good tuck she will max out at 122 and then I back off to hit my exit safely. Top speed for any extended period (10+miles) is usually around 85, but for me; The joy of being on my bike at 70mph with no fear of having to stop and talk to someone I probably won't like, is enough for me!!!!
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I feel most comfortable around 80-85 and the bike gets around 50mpg. I did 100 for 90 miles one day and only got 39mpg. 110 is all I've taken her to and only for a moment, the bike handles it well, but I don't need a ticket. . .
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I feel most comfortable around 80-85 and the bike gets around 50mpg. I did 100 for 90 miles one day and only got 39mpg. 110 is all I've taken her to and only for a moment, the bike handles it well, but I don't need a ticket. . .
Indicated or actual? I've found I only get 38mpg or so at an actual 80-85 (6000 rpm).
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+1 on that. I can almost watch my fuel gauge fall down in slow motion when Im really pulling on the freeway
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I got mine to about 115, and I think it could have gone to 120 if I wasn't already pooping my pants. :D
I like going 70mph. My S blocks the wind really well up to that point and its about 5k RPM in 5th. It's a pleasant place to be. :2thumbup:
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I feel most comfortable around 80-85 and the bike gets around 50mpg.
The only time i saw 50mpg was riding with a group at 60-65 mph. Above 80 my mileage drops into the high 30's.
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I feel most comfortable around 80-85 and the bike gets around 50mpg. I did 100 for 90 miles one day and only got 39mpg. 110 is all I've taken her to and only for a moment, the bike handles it well, but I don't need a ticket. . .
Indicated or actual? I've found I only get 38mpg or so at an actual 80-85 (6000 rpm). 110, WOT, it gets 27 mpg. Just FYI. :P
Wow! really?
My K1100lt with my 250lb including riding gear and using my gps trip got close to 45mpg with 35 miles of low speed streets and 65 miles of hwy going about 65mph. (Was with a group of Harley's.). Its amazing how much wind resistance goes up with speed and kills mileage.
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With just the back end weight Ive taken off already (i.e. police trunk, seat, rear fender and chopped frame) I notice a sizeable increase in speed. Where I would be around 70mph at 5000 Im now at around 73-74, cant wait to take off the fairing this week!
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I was beginning to get uncomfortable, but I had mine up to about 90 mph and was amazed how smooth the thing ran. The MPG sucked though. Of course, the fuel economy has always been poor on my bike. Still have not figured out why.
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I'm an 80 to 85mph guy. Fuck the police. Rather, I haven't been popped yet :neener: Beyond 85 it is a little less than smooth riding although I do occasionally hit 90mph when the wind isn't causing buffeting. Judging by the lack of a weight on the front wheel, I assume I need a good balancing. My naked K75 would cruise at an indicated 100mph pretty damn smoothly.
Top speed: I haven't pushed either of my K's to a top speed. Seems like I read some generic specs on the 75's and found the RT to clock a little faster top speed - due to the fairing I assumed. Yes it is more weight but it does punch the atmosphere and smooth the airflow.
MPG: 42 to 44 is the best I've seen from either of my bikes. Maybe they are capable of better but I just never happened to check MPGs? Running an indicated 75 or so, I can pull 42mpg on the RT. When I'm charging hard 85 to 90, I average 37mpg. Someday I would like to top off the tank, hit the 4 lane and cruise a solid 65mph and see what the average is.
Speedo accuracy: I haven't rigged up my GPS yet but the one roadside radar sign I encountered suggested my indicated speed is 3mph fast. The speedo said 61/62ish, radar sign said 58/59.
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I would love to get 42 MPG.
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I was just less than an hour ago hittin' some 100mph sweepers here in Kans-ass. She feels sweet n' stable, suckin' down and stickin' hard to the curves while accelerating thru 'em.
Fastest I've taken her is just a scootch over an indicated 120, which I'm guessing is around 110 in actuality. (I'm thinking there may be more, but have not had the perfect conditions in which to wring out every last bit)
Super comfy between 70 and 90, a bit of vibration north of 95, mainly due to tire balance issues I'm thinkin'.
When logging the long, slabby miles at an avg 80, I get around 43mpg. I stop at name-brand petrol stations and just use regular, but religious about using Mobil1 15-50 at 7,000 - 10,000 mile intervals.
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What would you say your RPM's are at when you guys are hitting lets say 90 to 95
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What would you say your RPM's are at when you guys are hitting lets say 90 to 95
6000=80. 7500=100
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Damn, same here. I dont like going over 6
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For my enjoyment I look at the average mileage for that particular road, and it is just frustrating for me to hit slow flow, so I average and most the time, it's between 60 to 65 the fun for me are the twisties, it seen to me that I always catch up with the speeding demon at twisties, because anyone can go fast on a straight way.
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Icant wait to go whipping through the twisties with my new clip ons and new forks. or pulling like a train on the highway
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Im just curious because anytime I hear someone say they can get a k75 to 120 I call bullshit, basically Im worried if my bike is messed up because when pushing my bike as hard as I feel comfortable doing I can get to 90, not saying it cant do more but it scares the shit out of me thinking its bad for my engine. Im not scared of going fast just worried about my bike. It may come from taking my Honda cb350 on the highway praying when I had to but I just want to know If I should be looking for a way to give my bike some more power. Running all stock rt wishing to do the ton comfortably. Please give me a reality check. ha
Cheers
I know this is an old thread, but I would be one to tell you that these bikes (my K75S anyway) are smoother the raster you take them. When I had the speedo at 128 I was actually going approx. 120 and smooth as glass....I miss my brick
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I'm guessing most have not and will never have these bikes near 120....not too many open roads etc. needed to get there. "comfortable"...speed?...120 is not.
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My K75RT and I hit 117mph on the GPS 1 up with top case, bags loaded up. I am not afraid of hurting the engine or driveline. I'm concerned about the tickets and, god forbid, the crash at 100+ with a deer or a cage.
There are quite a number of K bikes running around with over 200K on the meter. Do you REALLY think that any or all of the K series built 20 some years ago haven't been redlined, run hard and/or under maintained at some point or throughout their lives? We're not talkin Harleys here. The K motor is basicly a car engine with the pistons rotated 90 degrees to the side. It isnt some delicate little air cooled twin that can only go a few seaons withut needing a major overhaul. If history proves anything, the motor is the least of your worries.
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My '92 K7S stops being "comfortable" over 85. 70 is where she tells me she wants to be, and the most I have hit is 105.
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With just the back end weight Ive taken off already (i.e. police trunk, seat, rear fender and chopped frame) I notice a sizeable increase in speed. Where I would be around 70mph at 5000 Im now at around 73-74, cant wait to take off the fairing this week!
Might as well do a bit of dragging up old posts, what with the new year and all....
Are you saying that you had 70mph indicated on speedo while doing 5000rpm, then after ditching some weight you are 'now' getting 73-74mph indicated on the same speedo @ 5000rpm?
If you have the stock speedo pickup on the rear wheel and haven't recalibrated it then that suggests a problem to me - like a slipping clutch. The rpm/mph relationship should never change unless you change the gearing.
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I guess you are correct maybe the speed did not change outside of the rpms but where my top speed was comfortably at 70 I'd say now it feels comfortable around 73. I have put on a new speedo/tach unit
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70 for me on a standard, with a fairing I think 90 would feel ok plus ive got 128k mi on mine and actual bailing wire holding stuff on, too much can go wrong at that speed. not unlike my women I prefer slow and curvy over flat and fast any day :mbird
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Fastest posted speed I've been on my K75 (with the international shield on) is 110 mph. The shield just can't handle it for long and I don't think I'd be comfortable too long either. The 75-80 mph zone seems sweet for me. :riding:
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Top speed ever for me was 112 following come crazy Californian lady in West Texas, land of the flat boring straightaway that goes on forever. I never go first, but I often speed match the driver in front of me, about 80 meters behind. She got busted. I didn't. Then, same trip, I followed another crazy Californian at 105 for 90 miles. He got busted too.
Then in South Carolina I followed someone at about 105 for a half hour because my butt and hips were on fire from a 1800 mile 36 hour round trip for a funeral and i just wanted to get home. I think he got busted too...can t remember, that whole trip is a blur. I am obviously not a true ironbutt...the pain was excruciating.
But aside from that I'm comfy at 85, ok with bursts of 95+, most content at 75-80. Bike has almost 93k miles with Parabellum Scout 18" windscreen...which is an awesome unit...better in many ways than full LT or RT.
Van
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Comfortable up to 90 with the RT depending on wind (sometimes that faring feels more like a sail)
I literally just hit 120 on a deserted highway tonight to see what she could do.
….please don’t lecture me
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I want to lecture you, Andre. Please, please let me lecture you! 177381
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I had my fully loaded K75RT up to 108mph over the ground on the gps(the speedo is notoriously optimistic) in western Kansas where I ran 100+ for about 50 miles. These bikes love to run wfo.
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The max I ever got my K75RT to was 117 indicated. Substract the 10%ish factory error and that makes it about 105.
My best ride on that bike was 100 indicated for 250+ miles of sweepers from Watson Lake to Whitehorse in the Yukon.
(https://i.imgur.com/S7BsMcV.jpeg)
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Twenty plus years ago on a ride we all pulled over and were told if we wanted to do a top speed test run this was the ideal place for it . One of the guys on a 75 took off so I took off in pursuit. He stopped accelerating at around160 Kph so I opened up my 75s and blasted past at 190 Kph. He commented afterwards was as I closed all he could see was a black and yellow blur in his mirrors. My speedo was calibrated by Otto instruments and matches my GPS speeds. I pretty sure it would have gone to 200 Kph. It's never been pushed passed 160 Kph since.
Regards Martin.
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My K75RT and I hit 117mph on the GPS 1 up with top case, bags loaded up. I am not afraid of hurting the engine or driveline. I'm concerned about the tickets and, god forbid, the crash at 100+ with a deer or a cage.
There are quite a number of K bikes running around with over 200K on the meter. Do you REALLY think that any or all of the K series built 20 some years ago haven't been redlined, run hard and/or under maintained at some point or throughout their lives? We're not talkin Harleys here. The K motor is basicly a car engine with the pistons rotated 90 degrees to the side. It isnt some delicate little air cooled twin that can only go a few seaons withut needing a major overhaul. If history proves anything, the motor is the least of your worries.
I redline my K75s often. It doesn't hurt them at all. When I crashed my K75RT a long time ago it was just cosmetic damage and still rideable so, before parting it out, I rode it as hard as I could for a couple of weeks and tried to "abuse" the motor. That's when I discovered how "bulletproof" the K75 engine is and that redlining them doesn't matter.
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From the rider manual:
(https://i.imgur.com/oxratZF.jpeg)
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The only thing that concerns me at 100+ is whether or not there is law enforcement somewhere who will ruin my day. My RT was very stable and comfortable at 90+ mph. Never got to a speed where it wasn't.
As far as the engine, I have heard that the engine design was tested at redline under full power non-stop for 24 hours without any issues. I am inclined to believe that the Brick engine is the most bulletproof that BMW ever built.
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“Comfort speed” on my K75 RT is 140 km/h or about 90 MPH. That is drive-all-day speed except for the tickets of course.
Went at top speed for a bit on the autobahn with full fairing and saddle bags and it was ranging between 200-210 km/h but the road seemed to get narrower at that speed. I did not like it.
160 km/h is highest speed I was reasonably confident at for longer distance but that requires additional concentration and provides less buffer for the unexpected.
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The frame mounted Pitchler fairing is very stable and creates a nice cocoon. Toll roads near where I live have posted 80mph speed limits, and as you drive south towards San Antonio, the posted limit raises to 85. If you're not driving like a jerk the police pretty much leave you alone.
All that to say I've ridden 85mph legally, maybe a bit over (Officer quote after pulling over a lady I work with, "Nine you're fine, 10 you're mine") and on one trip did that for an hour. The bike was super stable, zero drama, big smiles. Felt like I was in Chermany. That said, I knew the bike was tight, and could tell you my exact tire pressure, oil levels, was fully safety-geared up as always, etc.