'78 R80/7 newbie questions

[apt13]

hi everyone. been lurking around the forum for the past month or so since i acquired this '78 R80/7 trying to figure out what i can with the little knowledge i have, a clymers book, and the help of a couple friends. i will be honest and say i am completely new to this and basically have no idea what i am doing, but i make up for that with my enthusiasm and excitement to learn. i am seriously having a blast with it.

the back story is that i acquired this bike through the usual internet channels. the previous owner made some minor modifications and customizations which i have slowly been trying to figure out or "fix" to the way that i would prefer. all in all, after some minor tuning, the bike seems to generally run pretty great (to the best of my knowledge), but i have a few questions that have been nagging me and i can't find the answers through the internet or through the books, and i was hoping you all could help or point me in the right direction. thanks in advance! and now for the questions. then i'll post the photos.

the previous owner removed the airbox/filter and choke assembly and cables and rigged up his own thing. luckily he gave me the airbox, so i was able to get most of it back together. first off, from what i understand, there is some kind of bolt (stud bolt and nut?) that holds the right side of the airbox onto the engine? i can't seem to find this bolt on the fiche nor can i find a decent photo of it. what is it and where can i find it? i have the bottom clamp installed which holds both sides of the airbox down, and i have the left side bolt and small clamp, i just can't figure out the deal for the right side. i am scared to start trying random bolts and nuts on the thing.

with the choke, i have the lever, i just don't have the cables. i see alot of used cables on ebay, but i am unsure about if they are the proper ones for my bike. would all /7 choke cables work? seems like alot of them are from R100s.

the previous owner removed the horn, i have it but there are no mounting bolts or brackets. i assume i can fashion something together, but i can't figure out where the plugs are that plug into the horn. i assume there is a relay because with the ignition on, it clicks when i push the horn button. perhaps a simple photo of a horn plugged in would solve my problem?

this brings me to the electrical system in general. from what i was told by the previous owner, he got the bike with the full kit of big fairings and bags and everything, so there seems to be an abundance of random wires which i have no idea what they are for. i'll spare you a photo of the mess in the headlamp full of random seemingly unplugged relays and cut and taped wires, that may be a job for later on, but i do have this relay that is just dangling by the battery on the left side of the bike. obviously it needs to screw into or onto something, but i can't figure out where. and for that matter, i can't figure out what the relay is for. i included the photo. any ideas would be appreciated. especially where i should attach it, the dangling scares me.

the previous owner added some random short mufflers. he gave me the original ones which i would like to put back on ( i would prefer the bike to be quieter). i included a photo of the old mufflers. are those big dents/crimps normal? the one with the smaller crimp up front seems like it may be for the brake on the right to fit? what could that larger one on the other one be for? or if i am completely misreading these things, let me know.

again, thank you for any info. as i said i have no idea what i am doing so any help would be amazing and exciting. i posted a pic of the full bike in the picture thread if anyone is interested.

 

[apt13]

sorry, won't seem to let me post the muffler pics. i'll try later if needed.

 

[20774]

Phil -

Welcome...the R80s were known for being silky smooth...

Be sure and check out this forum link to other sources of information:

http://forums.bmwmoa.org/showthread.php?t=47142

As for the airbox bolt/nut, I checked the on-line fiche at RealOEM but don't see it. I know what you're talking about. The fiche only shows pictures of the left side cover. I figured the bolt might show on the tranny picture but doesn't. Maybe someone will figure it out.

Re: the relay in your picture. The location of that relay suggests to me that it is the buzzer relay for the blinkers. Usually, it's mounted to the frame or the battery box up behind the However, the wires leading to the base connector don't look right as compared to this wiring diagram:

http://www.omnilex.com/public/bmw78/78r100wire.jpg

I see the prominent yellow wire leading to it and the only yellow wires on the above diagram go to items that would never be mounted there.

 

[dennisdarrow]

Phil....First of all welcome aboard. I really do appreciate your "can do" attitude and believe with that and a little bit of help you will get this straightened out......

The air filter cover. If it is the right side as you sit on the bike that you are having problems with, are you removing the nuts/bolts that hold the transmission on that the grooves, I believe in the air filter cover fit onto? I think I read that you have the "spring" type strap that goes across the bottom of the transmission and holds both sides down. Be careful when you tighten that bolt it is easily stripped.

The horn fits several ways over the years and perhaps the best way to find out is show up at a ralley to check out your year......Basically though they all go up on the front right corner of the engine. There should be some kind of metal strap or at least a couple of wires there by the frame........../5's were in front of the timing cover and were a real pain, and then the dual horn ones were placed on the other side opposite the top right side of the engine............

That relay looks like some kind of add on........trash?

Mufflers have those detents in them and they are basically for clearance for the axle removal during a tire change............

Do get in touch....PM me if you want......Am not far from you and if we cant figure it out on the phone, it's a great ride over on hwy 53........See ya and God bless......Dennis

 

[skiteach]

He's got the airbox cover on properly. There should be a bolt and nut holding the choke mechanism to the left side, seated on bike, in the casting shown.

 

[apt13]

thanks guys!

as for the airbox, i do have what is basically a strip of metal on the bottom of the airbox which clamps both sides together and down on the transmission. but the right side airbox (when you are sitting on the bike) is missing a bolt or something in the front bottom corner which holds that side snug. as kurt says, it doesn't seem to show up on any of the fiche diagrams. it shows the left side bolt, but the not the right. i am only assuming they are different. my guess would be a stud bolt (threaded on both ends) with a nut securing the right side airbox down? i just want to make sure i put the right thing in and strip the hole.

as for the horn, i think i've figured out where to install it, i'm just night quite sure what plugs into it. under the tank i remember seeing 2 "L" shaped plugs that werent plugged into anything in that general location on the right side of the engine. would that be the horn plug maybe? perhaps i'll take a photo this afternoon. why would there be 2? is that for dual horns?

and thanks for the muffler answer! makes perfect sense! so that huge indentions/crimp should be facing down, giving room for the rear wheel axle removal. gotcha.

and i do have the choke lever/bolt. i just dont have the cables, i figured i'd put it all on together. right now i just have to pull up or push down on the choke "buttons" the previous owner installed on each side..haha. works, but it's annoying.

thanks again!

 

[donbmw]

There is a stud in the engine block that come through the transmission case with a nut on it. This nut is losened and the RH side airbox cover slides in then the nut is tighten to hold the cover.

Your choke cables are solid wire.

 

[bmwwrench]

The right side of the airbox is retained by the top right gearbox mounting nut. When the airbox is removed for performance or cosmetic purposes, many swap the original stud and nut for a socket-head bolt. Aside from a 12mm hex, there is nothing special about the original nut.

The horn on an R80/7 is mounted to a tab on the left frame down tube. This tab is present on both sides on all '77-'84s. A plate connects the tab to the horn.

That relay is for the turn signal buzzer. There would have been a 90 degree sheet metal bracket to attach it to the left, rear-facing battery mount.

 

[apt13]

excellent. thanks!

any idea where i can get that bolt and nut for the airbox? is it listed in the fiche and i'm just looking in the wrong place? the previous owner stuck a hex bolt in there but it is too short and doesn't fit when the airbox is installed.

i'll also see what i can do about that relay. i assume i can fashion something around that battery case for it to attach to. thanks for that info.

 

[20774]

You might take a spin to Boxerworks pretty near you. They most likely can help out. Otherwise, Ted Porter at http://www.beemershop.com is a good source for stuff as is Hucky's BMW in Florida http://www.bmwhucky.com/.

 

[apt13]

cool. thanks. ive been by boxerworks a couple times actually when i first got the bike for some odds and ends, it's very close by and nathan seems killer. i was just hoping to knock out a couple things on my own before showing up in his garage with another silly list of nuts and bolts...haha. i don't want him to get sick of me this quickly.

 

[bmwwrench]

The stud is found in the cankcase section of the 'fiche. Part number: 07129908137


The nut is found in the gearbox section. P/N: 11611713432

If you want the washer: 07119904115

 

[gertiektn]

Study the wiring diagram.

I believe that the horn wires are black/Grn stripe. They are switched to ground.
That would be a solid black or brown.

With all the extra wiring.... be suspicious of all and get a continuity tester or make one with a small 12 V bulb and trace, trace, check and double check.

Get intimate with the bike and study it.

good luck on this project.

Jim, Ketchikan, Alaska

 

[apt13]

thanks a bunch! those seem to be the parts i am looking for. now i can get those on there and stop worrying about that section. haha.

as for all the wiring (including the horn), i am really dreading opening up that can of worms. i've got the diagrams, i suppose i'll just have to sit down and just go through it all. just knock it out and stop worrying about it.

thanks again everyone. i'm sure i will be back with more questions soon!

 

[ISAMEMON]

yes wiring can be a can of worms
the biggest error I have seen with these bikes and bmw cars, is people dont remember the ground color

remember ground is dirt
dirt is brown
therfore..... ground is brown

and from what I remember about my 78 R80, that looks like the turnsignal buzzer