new to just about everything. help me get this 86 k75 going.

[healthy]

Hi everyone!

I'll get to the intro in first, then there will be some questions farther down to those who know about these things.

I'm pretty green. i haven't owned a bike before, and i haven't wrenched especially heavily (aside from working on some race cars with an uncle about a decade ago). I am, however, fairly technically inclined. I'm a mechanical engineer by trade, and over the last few years my go-to project has been working on opensource 3d printers (reprap.org).

I've wanted to work on bikes for quite a long time, but college (and college dept) and a garage-less apartment kept me away from it.

anyway. been looking at options for the last couple of years and (like many people here, obvsly) ended up in love with the idea and style of k bikes. been following local craigslist ads and one finally came up that i jumped on. there were several over the past year, but the stars aligned with this one, especially the part where it was dirt cheap since it was not run in the last 4 or 5 years.



It is an 1986 K75 with 135k miles. the previous owner had it since 1993 and really just didn't ride it very much since he was more into racing and has several other bikes (he mentioned he got it with about 100K.) It has always been garage kept so the bike itself is in great shape.

All the trouble so far comes from the fuel that was in the tank. it had broken down and left everything covered in yellow film, and all the rubber parts had broken down


my pump was done. (it would twitch when connected directly to a battery, but no whirring) and obviously i needed to replace all of the hoses and filter. i ended up getting the alternative pump from advance auto parts and "made it fit". (i might still do the techron soak to see if the original comes back to life)

now it pressurizes the line, but still doesn't start. (i'm considering getting a pressure test gauge to see that it is getting to the 36psi that the pressure regulator maintains)


Q1: do you think the pressure regulator might be affected by the same kind of clogging? I don't know how it is made up internally(i might just get the gauge to verify it)

i've verified that all cyclinders have spark. and so my current thoughts are that the fuel injectors are clogged just like everything else in the fuel system. I'm going to send them tomorrow to Mr. Injector.

I pulled the injectors off today and had a hell of a time trying to clean out the crevice around each one to ensure that nothing falls into the engine. compressed air wasn't enough, i had to go in there with a sharpened bottle rocket stick. yeah pretty high tech over here.

anyway, after i pulled them i found that injector number 2 didn't meet the standard 16.1 ohm resistance, with only 13.4 ohms. so there is a short here.

Q2: is this a show stopper? (obviously after all injectors are unclogged). it is better than an injector with an open coil, but will this trigger at all? or will it simply have a low fuel spray and all the roughness associated with that? i guess i'll see what mr. injector's report says.

I'm sure there will be other issues to deal with but the whole starting thing seems to be pretty important.

I did have one previous question that came up when i was dealing with the fuel pump thing. lots of mentions in various posts, and even some YouTube video shows (figuratively in the posts and acoustically in the videos) the fuel pump priming when the key is turned on, prior to hitting the starter button. i know now that my fuel pump is only triggered when the starter switch is hit and not before. does this have to do with the fact that i have an earlier model, or is it and issue with my controller or my hacked in non-oem pump?

OK. so long first post, but hopefully it gets me some help. any help here would be appreciated of course, but if there is anyone in the Chicago area that can lend a hand, or at least would be up for a victory ride at some point after i get her running, i'd like to make their acquaintance.   

Thanks,

Andres

[Rick G]

I would say that 13.4 ohms would be OK.
It,s a bit on the low side but it still should trigger. Go with Mr Injector he does know his stuff.
I have found that if you leave the tank out in the sun (could be difficult there at this time of year) the crud will turn to a dust and vac out fairly easily. Check the paintwork on the exterior under where the pump sits and make sure there is no corosion causing holes.  As for the Fuel pressure regulator it does have rubber bits so if the rest of the rubber is shagged then chances are it will also be on the way out.

[jeffhestand]

great looking bike. I too just bought a K100. ( first BMW). I did not even mess with the bmw fuel pump when it quit running. I did the OEM purolator switch for 1/4 the price and a Wix fuel filter and it works and runs like a champ.

[Roy S.]

Welcome aboard

[healthy]

Thanks!

right now i am just worried about shipping these to Mr. Injector because the package smells of gasoline. that won't cause a fuss, right?

[frankenduck]

I've Priority Mailed many sets of Injectors to him - never a problem.  Put 'em in a Zip-Loc.

Worst case his post office will make him come and get them in person.  I mailed a used fuel pump to somebody and the package smelled like gas by the time it got so they made him pick it up in person.  Not z big deal.

[healthy]

Good news everyone! after a lovely 10 day trip with my wife split between barcelona (saw 4 k75s parked various places) and cairo (saw no k75s, but did see some dudes pulling standing wheelies over the bridge from tahrir square on some small chinese made bikes), i came home to my package from Mr. Injector.

AAAAnd, after installing them (oiling the new o-rings of course) i was able to get the bike started after 15 or so seconds of turning over! there were some new sounds of it starting to catch before it started purrwhining that k-bike sound i've heard in various youtube vids.  I imagine it took that long just to get the fuel through the entire fuel bar and line and up to proper pressure. everything smoked pretty good for a little while, but that ended up burning off. it put it through a few miles of riding and then stopped back home to change the oil and filter (i know the PO had changed the oil, but the oil filter was definitely old). i need to change the trans and final drive oil too, but i only had one container to store the motor oil. i'll pick another one up soon and change that this week).

I still need to get the old tires replaced, so I didn't want to go through too many miles. but I rode it around the neighborhood a bit and it was a blast.

i know the transmission is normally pretty "clunky" but i'd definitely like to find a second opinion sometime just to make sure that it isn't worse than normal (or if it is, what i need to do to fix it.)

also, another point of good news today. a couple of weeks ago, when i was cleaning/replacing what i could in an alley behind my friend's house, a british gent passed by and we shot the shit about the bike for a little while. he mentioned he knew the guy that started the bmw club in chicago and that he'd get me his contact information. he also mentioned that he had recently sold his bike (going back to england next year) and still had some gear and a helmet if i was interested.

now that i was back i gave him a ring and he ended up giving me a helmet, two pairs of gloves (winter and summer) an armored jacket (with reflective vest) and a pair of pants with removable insulating layer for about $50. shortly after that he called me up again and offered a free small air compressor for my friend's garage workshop i was working out of. definitely a nice day. (aside from the fact that the dude was tall and the pants don't fit.)

now i just need to get some last items on order (like the new tires) and i should be closer to some longer riding very shortly. i did notice some oil coming through the weep hole under the transmission, so it looks like my main seal needs replacing, can that be an at home job? anyone with some good tips?

here is a short youtube vid of it's first run. hard to see but there is plenty of smoke that cleared up after a while.

[frankenduck]

When they sit for long periods, especially on the side stand, oil seeps past the rings.  That's what caused your smoky startup.  Once it's burned off the mosquito fogging subsides.

Chances are that it's not the main seal but the clutch-nut O-ring has dried and cracked.

[conybeare]

Nice work! That looks pretty clean for the miles.

[jeffhestand]

looks like your on your way. Wish i have a 75 but i guess ill make do with my 100. 

[healthy]

oh the smoke definitely cleared. This video was of the first start, i've since ridden it around some and smoke is pretty minimal on subsequent starts (from center stand at least).

is the clutch-nut 0-ring a tough replacement? i haven't had a chance to look through my clymer's for where it is, but i'll probably do that this evening after I catch up with all this work stuffs.

[healthy]

well now to find all of the rest of the problems. with one hand it gives and with the other it takes away.

(this sounds worse than it is)

The bike is running pretty well. had some shifts into second that didn't take but that is likely user error.

The issue i found now (and likely not the last) is that my speedo cuts out. (and i presume that my odometer does as well) going over some speed humps and general rough chicago streets, it looked like my entire headlight cluster bounced a bit much (or maybe the normal amount). my speedo would be showing at least relatively correct speeds and then drop to zero. sometimes coming right back up, otherwise staying on or off for unpredictable amounts of time. obviously i was also watching the road so i didn't catch it enough to tell if it is precisely with bumps.

how would you guys approach trouble shooting this? I believe the sensor is on the back, so can i put it on the center stand and have a friend hold a constant throttle speed while i probe around? ill advised maybe, just seems easier than studying the wiring diagram enough to clip in and test continuity (though i guess i'll have to do that anyway in order to fix whatever problem is there.)

[frankenduck]

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