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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: ermach on May 13, 2013, 03:57:28 PM
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I've been lurking on the site for a while, and here is my first post/problem. I picked up an 87 K75 just a month ago and have had my share of ups and downs with this bike already. Love the 80's tastic looks, hate the handling. The second day I had the bike, I had to push it home. I later found out the seat was squishing the leads from the fuel pump. relocated the harness out of harms way and all was good. I got a used progressive rear shock for it, since the original shock had zero damping and about an inch of absorption. The original issue was the bike made me feel like a snake charmer. It literally felt like it was completing a slalom course under me at certain speeds. The shock has made a 90% improvement, but sometimes it still happens. I read a post about replacing the rear shock, and that curing the issue, but mine still persists. I know that bias ply tires are not the bee knees, but is this normal? I have got Michelin macadam's on it right now, and they look pretty much new. I had bouncy front forks, which i firmed up with some new, heavier fork oil and plan on new springs eventually, but this issue is killing my confidence with this bike. I am used to newer sport bike handling, and realize this bike's age, and that it isn't a sport bike. wheel bearings seem ok, as does the steering adjustment. what else can I look for? any help is appreciated
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Steering head bearing adjustment on these is unique to a K75. Before checking the tightness, you need to loosen the grub screws that hold the fluidblock damper, otherwise you will get resistance from the damper. It is also possible the grease in the fluidblock has lost it effectiveness, check this article: http://www.ibmwr.org/ktech/fluidbloc.shtml (http://www.ibmwr.org/ktech/fluidbloc.shtml)
Head bearings to tight or loose can cause wobble, so can a bad fluidblock damper. The grease they mention can be substituted with Corning High Vacuum Silicon Grease, also known as stopcock grease.
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High miles?
Id go through and check wear items. Things like slop in the swing arm, Service the head set if it hasn't been done and see if you find any issues there. Even if its low miles the head set may need service as the grease dries out and may make the headset bearing notchy from lack of lubrication.
Tires rot from the inside out. Over 7 years old Id strongly conciser replacing despite what they look like. On the side of the tires will be a date code. It will be 4 digits. first two at the week and the second two are the year. Here is a little more info and a picture of what you are looking for. http://blog.tirerack.com/blog/hunters-ramblings/how-old-are-the-tires-i-buy (http://blog.tirerack.com/blog/hunters-ramblings/how-old-are-the-tires-i-buy)
As for tires. I had a VERY old set on my bike when I bought it. I took recommendations here and went with radial tires and VERY impressed with the change in the bike. Before the new tires it felt like you have have really force the bike to lean into a curve. Now its just seems to flow into curves.
Duck recommended to me Avon AV46 140/80-17 and Bridgestone BT023 110/80-18 for the front. I think your wheels are a little different size then my K1100LT. Id search "K75 tires Radial" and see what posts you find. I found really good prices on the tires I bought from http://www.motorcycle-superstore.com/ (http://www.motorcycle-superstore.com/) and was able to get my tires to my door for $275 for the pair. WAY better then I found locally and they still had to order them in.
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Ok, all of the above is great advice.
I have a K100RS 89. I changed tires, Lazortecs, not radials, put in new headset, greased, tightened, adjusted, changed fork oil and progressive springs, and new Realm shock on the back. All the suggested things to adjust. Did it get rid of the wobble at 49-51 mph......nope.....now I live with it.
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a wobbling motobrick is a character builder...
j o
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And great for developing anal sphincter control :giggles
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The metal bands split on the inside of my front tire. Serious wobble just randomly occoured while doing 65ish. I could have just bought a gallon of Preparation H. What year are the tires?
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Another vote here for starting with the tires. Age, and pressure. Sometimes it's the simple things.
I've been extremely pleased with my Bridgestone BT45s on front and rear. Unfortunately it's just been discontinued in the front size, but apparently their S11 Spitfire is also good. I'll be finding out soon.
You didn't mention which '87 K75 model you have. It may or may not have a fluidbloc damper.
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It seems more likely of a tire issue. I hadn't looked real close since they have tons of tread and the nipples still attached, but after looking at the date code as mentioned, they are 9 years old and have a little cracking in the sidewalls, awesome. Also, I had no idea that it could have a fluid damper inside the headstock, so I'm really glad I posted here, tons of great ideas. The fact that I may have to live with it doesn't excite me, but makes me feel better none the less, like I'm not crazy, and this really does happen to other people. I didn't mention what model, because the previous owner wasn't really sure. It has the drum brake and 18" wheels front and rear. I traded a DR650 for it on a whim, and other than some trans oil and coolant top off, fork oil, and the new shock, have just been putting the miles on. Also cleaned the speedo sensor last night, since on the ride home it would work, then stop, then work again. seemed fine on the ride into work today. I think I am on the verge of being happy with this bike, which is huge. The only other bike I can say that about was my first, an SV650. I'm going to get some new tires as soon as possible, probably replace the steering bearings and maybe order a new fluid damper. I think the bike sat for a while, and now that it's out in the world again, I'll have to work through a lot of little issues before it's 100%. Part of the brick charm though, or at least what I'll tell myself
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a wobbling motobrick is a character builder...
j o
I hope you are kidding on this one, because my 85 K100RS is definitiely lacking on THAT quality. My bike was riding on 18 year old tires when I got it and it was a bear to ride on the freeway. The bike followed all the grooves and didn't want to turn. With a set of new tires plus new rear shock and front oil, it's actually very responsive for a 28 year old bike. I would say it handles as well as my 1150GS (that's not saying much, I know) did when I got a brand new.
I think of all the things I did, tires and suspension updates are definitely things I can feel. Now I just have to find time to swap out the handlebar bushing pieces to fix that flex.
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Nine years old? Yeah, start there.
If you have the rear drum brake it's not a K75S, which has a disc (all years, as far as I know?). What sort of fairing/bodywork does it have?
You likely have a K75C or K75 standard/naked. You likely do not have a fluidbloc damper, so you probably won't have to replace it.
I'd hesitate to tear into the steering head until you've gone through the easy things (tires, rims, fork alignment, maybe wheel bearings?). You will be coming across plenty of required repairs as you get to know the bike. A that age - same as mine - all the rubber is dying, and havoc ensues. Fixing what ain't broke adds to the expense, and frustration if unexpected required repairs hit at the same time.
I'm not arguing against good solid preventive maintenance, by the way, and if you happen to be set up to do bearings easily, have at it.
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it's actually this bike here:
http://www.motobrick.com/index.php/topic,3283.0.html (http://www.motobrick.com/index.php/topic,3283.0.html)
I didn't see this post until after we traded, he didn't make much of an attempt to inform me about the mileage being not actual. It wasn't until I saw some of the service records that indicated work done at 47k and the odometer said 32K. A lot has been replaced/serviced on it so I felt a little better except for the fact I couldn't keep it running on day 2 (because of the fuel pump lead). I was freaking out and he was no where to be found. I ordered some tires today, not much in the way of an 18" radial for the rear so I cheaped out and got some shinkos for now. I figured even if they aren't great, 2 brand new tires would be better than rolling the dice on some 9 year old buns. I need to find the stem adjustment procedure and do that. I'm going to try all of the service items discussed instead of throwing tons of new parts at it. I don't have any presses for bearing install/removal, but I do have a dremel and a chisel. But like I said, new tires and some adjusting, I'll see where that takes me first.
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old bikes are by name, old. The mileage probably isn't as critical as overall shape. I bought the Metzler Lasertec for the front and back. They are not the best, but they're not the cheapest. I have bought cheap tires for my cars in the past and regretted every single time.
Do you have a bend wheel? I guess you'll find out when you get the tires mounted. My bike does not wobble. I have ridden a CBR with bend clamp and bad head bearing from user abuse and that bike didn't wobble either. It just wanted to veer sideways and its front end moved under braking.
Good luck with the bike. It does look good.
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Hey, that's a great looking bike. If it's around 50k it has lots of good years left. But at that age, no matter how low the miles, the rubber is all dying. Start stocking up on o-rings. Here's some stuff I would absolutely change as a matter of good preventive maintenance, unless you have a record of recent replacement:
- Fuel filter
- In-tank fuel hoses. The BMW submersible fuel hose is the best deal around, at $26ish per meter - NAPA charges that much for a foot of the stuff.
- External fuel supply hose (the short one going to the front of the fuel rail) - any 5/16" FI-rated hose will do
- Crankcase vent hose - about $15 - this is the little z-shaped thing near the back end of the fuel rail that goes from the engine up to the air box.
- Brake hoses, if you don't mind putting the $$ into it.
- Fuel return lines & pressure regulator vacuum line - The short fuel return line from the rail to the pressure regulator is plain 5/16" or 8mm FI hose. The one from the FPR to the tank is a shaped BMW hose. You can substitute plain hose, but it's awkward. For the vacuum line, one foot of 3/16" vacuum hose from NAPA. This can wait til you have some other reason to pull out the air box.
Things I'd order up in a batch, because they're cheap, and eventually you'll need them and be pissed if you have to wait a week and pay $9 shipping to get a $1 part:
- Brake reservoir o-ring
- Several oil drain plug crush washers
- The other assorted crush washers - trans & final drive drain & fill, fork drain plugs, brake hose connectors, coolant drain plug, etc. Comb through the parts fiche and get a couple of each, or find a package at BeemerBoneyard.
- A couple oil filter cover o-rings. These will last several oil changes. BeemerBoneyard sells the o-rings and crush washers in various nicely-priced bundles. Dealers don't want to sell you just the o-ring; they want to sell you a $20 oil filter with the o-ring.
- Fuel sender o-ring - You'll pull the sender out eventually, and when you put it back together the crusty old one will leak fuel all over your relay box, or your crotch/inner thighs. DAMHIK.
- Rubber bushings for the valve cover and crank cover, 10 on the left and 8 on the right IIRC. $0.63 each. The tension from these, not the torque on the bolts, is what holds the covers tightly against the gaskets, preventing oil from weeping out the joint. If yours haven't been replaced, they're old, dry, and no longer exerting pressure, so when you take the cover off you'll break the seal of accumulated crud that's currently holding it together.
Seriously. If I were to get another one of these bikes, I'd just order all this stuff and replace it over a few weekends.
Also, my clutch cable broke a couple weeks after I got the bike. Fortunately I was a couple blocks from home and in second gear, which made it easy to turn around and park it in my driveway. Five minutes later and I'd have been doing 70 on the freeway. So even if you don't go for replacing it, at least open up the lever and make sure the little barrel pivot thing is well lubed, and that the cable doesn't have any broken strands. (This may require learning the adjustment procedure. Or you might be able to just relieve tension by jamming a piece of wood between the clutch arm at the transmission and the muffler so you can pull the hand lever apart.)
Several dealers have good online parts fiches and good online order handling. I've happily ordered from:
http://www.maxbmw.com/ (http://www.maxbmw.com/)
http://bobsbmw.com/ (http://bobsbmw.com/)
http://bmwmcchattanooga.com/ (http://bmwmcchattanooga.com/)
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I had a weird wobble/sway/weirdness going on (felt like the bike was following a rain groove, when there weren't any). A new front tire and wheel bearings cured it completely.
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I had a weird wobble/sway/weirdness going on (felt like the bike was following a rain groove, when there weren't any). A new front tire and wheel bearings cured it completely.
To OP, please let us know what it turns out to be. Be safe.
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got the tires on friday, will mount them up this week, hopefully by wednesday. I hope that cures the issue, but will move on down the list of things to check if not. I'll post up and tell what helps get rid of this
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Less than a dollar of washers was all it took. I read about "frame alignment" and thought I would check it out. All you have to do is loosen each bolt that mounts the frame to the engine and see if these is a gap. I had a significant gap at one of the mounting points and another smaller gap at a different one, so I removed the bolts, one at a time, put washers between the frame and engine, buttoned it up and it's a whole new world. If the wobble is not totally gone, it's 95% gone, which is good enough for me. Also, I was hesitant about the shinkos, but they are WAY less prone to search out the groves in the road and actually allow the bike to feel comfortables in turns. I still have various maintenance to do, but it's getting to closer to the way I'm sure it felt when it was new. Johnny blanket mod a must down here in Texas, I never knew a bike could be so hot, so that's on the must do soon list as well.
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greetings ermach...
thats freaky... i know what im gonna do the night before midwest motodebauchery while the moes are sleeping... he he he... gonna be a wobbly weekend for them... ha ha ha...
j o
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a wobbling motobrick is a character builder...
j o
Good one, got a good chuckle. I must be lucky as hell. My 87 K75S is so freakin smooth at 110 mph I can't get believe it. I can't get it to wobble.