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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Gudlukinz on March 10, 2020, 07:42:30 PM

Title: 1985 k100 tank leaking
Post by: Gudlukinz on March 10, 2020, 07:42:30 PM
Not completely sure what I’m looking for to replace, but it seems like it’s leaking through the cables. Any help is greatly appreciated thanks. Picture attached
Title: Re: 1985 k100 tank leaking
Post by: Gudlukinz on March 10, 2020, 07:48:45 PM
Another pic

Title: Re: 1985 k100 tank leaking
Post by: Martin on March 10, 2020, 08:27:01 PM
A used sender from Motorworks UK is 65.00 Pounds plus freight. They seem to be getting harder to find. You could try local BMW wreckers.
Regards Martin.
Title: Re: 1985 k100 tank leaking
Post by: Laitch on March 10, 2020, 08:31:12 PM
Not completely sure what I’m looking for to replace, but it seems like it’s leaking through the cables. Any help is greatly appreciated thanks. Picture attached
Welcome! I spent three truly strange years in Bradenton—1969 though '72. I still visit the beach and pier on Anna Maria Island.

Following on from Martin's post, judging by the fuel line next to the leaking fuel level sender, you probably should replace all your high-pressure fuel delivery line. That's the one to the right of the leaking fitting. Use a fuel injection clamp like the one on the hose to the left of it instead of the weaker slotted clamp on it now. Probably replacing all the rubber high-pressure lines would be a good move. Is the interior of the tank clean?

What's leaking is the obsolete fuel level sender. It might be that just the o-ring within the cap needs to be replaced. You won't know until you unscrew that assembly and look.  Disconnect the battery ground cable on the transmission before you mess with it. Be careful. Current to the fuel pump and fuel light on the instrument cluster are functions of those wires; they might be brittle. This type of gauge is obsolete. If it's damaged, you might be on a long hunt to replace it. Get acquainted with MAX BMW's parts fiche (https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51747&rnd=07242017).

Attached is a drawing of the fuel level sender. It's in the red rectangle; the green arrow points to the o-ring. The part number in the fiche is in the second image.

(http://www.motobrick.com/gallery/2/1601-100320202513.png)

(http://www.motobrick.com/gallery/2/1601-100320202625.png)
Title: Re: 1985 k100 tank leaking
Post by: volador on March 10, 2020, 08:41:01 PM
Welcome & good luck with moto

(http://www.motobrick.com/gallery/2/5332-100320203828-28381061.jpeg)
(http://www.motobrick.com/gallery/2/5332-100320203821-2837994.jpeg)

http://www.motobrick.com/index.php/topic,12340.0.html (http://www.motobrick.com/index.php/topic,12340.0.html)
Title: Re: 1985 k100 tank leaking
Post by: Gudlukinz on March 10, 2020, 09:04:07 PM
Very nice, ya Anna Maria is gorgeous. Actually a firefighter paramedic right next door at longboat key. thank you so much for the help, so the sender just unscrews out the bottom? And ya I’ll replace the fuel lines.
Title: Re: 1985 k100 tank leaking
Post by: volador on March 10, 2020, 09:37:19 PM
so the sender just unscrews out the bottom?

Yes, fragile proceed with care
Some info for 1985

Notable differences of the pre-85/86 K100 are the seat pan design with matching tail cowl section, the water/oil pump design changed, throttle cable design and fuel tank/fuel level sender/fuel return check valve.

Your moto may have the European "hotter" cams known as "Finest Year K"

http://www.motobrick.com/index.php/topic,3653.msg56782.html#msg56782

https://forums.bmwmoa.org/showthread.php?4534-Why-is-the-85-K100-the-quot-Finest-Year-K-quot&s=66f149b3cadea44550d51fbf0b9ee793&p=42512&viewfull=1#post42512

The pre-1985/86 has molded pillion handles as part of the seat pan, metal or plastic seat pan.
Post-1985/86 removed handles from seat pan and added handles to the tail cowl section.

http://www.bmwkbike.dx.am/CLseats/kbikeseats.htm

Water Pump
pre-1986-87? original design old style impeller 11411461177

Superseded by 11412325850 design change the shaft with gear Z=32 teeth, shaft- 11411461183

Superseded by 11417676366 same shaft with gear Z=32 teeth

latest design 11517676371 design change shaft with gear Z=19 teeth, shaft- 11411461793

Throttle cables have 2- versions and lower brackets. Cable lengths vary with handlebars.
#1 version- have a adjustment sleeve approx. halfway down length
2nd version black plastic collar at the lower end or a white plastic collar

Pre-1986 fuel tank has a rear mounting tab later removed and changed to mounting pins and grommets.
Early fuel lever sender is a thermistor type later is a float type.
http://www.kforum-tech.com/how-to/Modification%20for%20early%20gas%20tank.htm
Good Riding