New rider to the BMW family in the PNW

[boomguy554]

Hi everyone, I picked up a Red 88 K75S  for a song about a month ago and I figured I'd finally get around to registering on here. It's been sitting for about 10 years so I'm slowly bringing it back to life. It's stablemate right now is a RC390 track bike since I'm a fairly avid trackday rider. I'm looking forward to getting this old BMW back on the road and taking it on some good trips. I'll try and post some pictures of it later since it doesn't seem to like me trying to attach them from my phone.

[boomguy554]

Well it doesn't seem like I can edit my post, but the picture uploaded and it's definitely an 88, not a 87.

[bocutter Ed]

You need 10 posts before ...

[volador]

Welcome nice looking moto. Looks like fairing is in good nick and just needs a good cleaning.

You can add the last 7 digits of the VIN into the MaxBMW model search link. Good luck

Just bought a 2V

Just bought a 4V

Check parts compatibility with BMW MAX Microfiche, BOBS BMW, REAL OEM

https://shop.maxbmw.com/fiche/PartsFiche.aspx

https://shop.maxbmw.com/fiche/PartsSearch.aspx

https://parts.maxbmw.com/BMW___BmwMotorradK.html

https://www.bobsbmw.com/store/microfiche/BrowseSeries.aspx

https://www.realoem.com/bmw/select.do?kind=M&arch=1

https://www.ascycles.com/BMW-Motorcycle-Parts-Fiche

Cross reference parts like Bosch pn#'s, etc....  http://partsplusecat.com/
No spaces in the part number

Parts Vendors

https://www.beemerboneyard.com/

https://www.capitalcycle.com/

https://www.euromotoelectrics.com/

https://www.tills.de/

Headlight relay stuff if you chose to add one

https://www.motobrick.com/index.php?topic=268.0

http://www.motobrick.com/index.php/topic,4962.msg30932.html

http://culayer.com/product/matchbox-headlight-relay/

http://easternbeaver.com/Main/Wiring_Kits/H4_Kits/h4_kits.html  Eastern Beaver site is a great reference for electrical connectors,plugs, etc...

http://www.k100-forum.com/

http://www.kforum-tech.com/Tech-page.html

http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm

http://www.kforum-tech.com/Downloads/electrical/diagrams/interactive_diagrams.htm

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/k100tshoot/K100.Troubleshoot.Start.2018.pdf

http://kbikeparts.com/index.htm

http://www.kbikeparts.com/classickbikes.com/ckb.tech/ckb.new2k.htm

http://www.kbikeparts.com/classickbikes.com/ckb.tech/ckb.tech.toc.htm

http://www.eilenberger.net/K75S/IgnitionSwitch/

http://www.verrill.com/moto/moto.shtml

this site has a lot of good info and breakdown pictures in the tech and tech resources sections for K1100 alot of the parts are on K75 & K100

http://www.k11og.org/forum/index.php?sid=2df953dde5715fd9001fbe69edec5ad0

https://ibmwr.org/index.php/k-bike-tech-articles/

This site has all kinds of technical specifications on all the BMW models    http://www.bmbikes.co.uk/mechanicalpages/kseriesmechanical.htm

http://largiader.com

http://bmwk10075abs1fix.web.fc2.com/index.html  Toshi ABS site

[K1300S]

welcome!  looks like you grabbed a nice S!

[natalena]

Welcome aboard, great looking starting point for a brick.

[boomguy554]

Well I got it fired up for the first time last night, and it's definitely a little smokey. Hopefully it's just all the fogging oil I sprayed into the cylinder originally, otherwise it's going to need some new rings🙃. Thanks for the welcome and help so far everyone!

[natalena]

and it's definitely a little smokey.

I wouldn't worry about the smoking yet, like you said, probably fogging oil ... or just a quirk of K75's that have been on the side stands after running. While changing out spark plugs, it's easy to do a quick compression check. How many miles are on it?

[boomguy554]

Compression test was about 105-120 between all three cylinders so it's not great. Could be the rings from sitting for so long needing to be set again. It's got 42,xxx mi on it.

[The Mighty Gryphon]

42K, they are still being broken in.  If it's been sitting for a  couple years, they could be stuck and need to free themselves up. 

When you did the test, were you holding the throttle wide open and have all the spark plugs out?  Fresh charge on the battery to spin the engine? 

[boomguy554]

I didn't hold the throttle wide open and the battery could probably use a charge again before I redo the compression test. It's been sitting for at least 10, maybe 14 years. The plate on it had tabs last in 2006.

[The Mighty Gryphon]

If the throttle wasn't wide open and the plugs out with a strong battery you will get readings like you are seeing. 

Sitting 14 years can stick the rings.  I had that problem; on my bike they gave good compression, but allowed a lot of oil to get past them.

Do the test over again.  I'll bet you get some nice readings in the 160-170 psi range

[boomguy554]

That would make sense. The numbers seemed a little low even for a bike that's been sitting for so long. I'll throw the battery on the trickle charger and try it again tomorrow. This is the first time I've ran into an issue of sticking rings so any tips on getting them to unstick? Just running it until they free up?

[The Mighty Gryphon]

See what the compression looks like and how much oil you're using first. 

If the battery has been run down a lot, the trickle charger may not have enough output to bring it back to full charge.  Most trickle chargers only put out a couple hundred milliamps.   Do you have a regular charger you can put the battery on overnight?

[boomguy554]

The battery is only a couple weeks old, it would have been worn down from cranking the bike over a lot to get it started but the voltage is already back up to 13 with the trickle charger so it's good to use.

[volador]

squirt some Marvel Mystery oil or penetrating oil to top piston head in each cylinder while it sits waiting help loosen rings up

[The Mighty Gryphon]

That 13V may be a "surface charge" which quickly goes away when the battery is used.  Turn on the lights for a moment and then check the voltage again. That will give you a true idea of the charge.  That voltage should read at least 12.8 volts. 

It will be interesting to see what the compression test results are with an open throttle.  Make sure to get at least 5-6 compression strokes to get the reading.

[boomguy554]

Having the throttle wide open sure makes a hell of a difference. I tested each cylinder three times and got way better numbers. 175-190 for cylinder one, 160-180 on cylinder 2, and 185 every time on cylinder 3. Thanks for the advice everyone.

[The Mighty Gryphon]

That's great!   

Just remember, the compression test measures the ability of the engine to compress the air in the cylinder.  You gotta have the throttle open to get some air in there to compress.

Now just keep an eye on how much oil the engine is using to see if you have any stuck rings.  Normal is at least about 1200-1500 miles per quart on my bikes.

[boomguy554]

I'll definitely keep an eye on the oil level, but before I get anywhere near that amount of mileage I definitely think new tires are in this bike's future. Taking it for a spin around the block is only slightly terrifying on these 20 year old Metzlers...