Author Topic: New Brick in NoVA  (Read 6233 times)

Offline Shiny

  • Motobrick Curious
  • Posts: 49
New Brick in NoVA
« on: August 06, 2016, 02:26:46 PM »
Hi all,
Bought a K75T a few months ago, been slowly getting it roadworthy again. I bought it liking the look but not really knowing what I was getting myself into, i.e. what shaft splines were or any of the other quirks of these bikes to look at when buying used.

The bike I bought has 35000 miles on the odometer, but the odometer doesn't work. Front end had a little pulsing under braking but it shifted smooth on my test drive at the buyers house. The headlight fairing was cracked, held together with piece of cardboard. Most egregiously the coolant reservoir tank was missing!  :mbird The return hose was routed through the frame to the ground. I'm ashamed to say I didn't notice that until I got it home...

Once home I ordered the Clymer manual and got to work. I read up on the shaft spline job and started pulling pieces off. Luckily the splines weren't too shot. They were covered in the red BMW lube at some point.

Next was a valve check because there was some hesitation when opening the throttle. The exhaust was super tight, measured 0.215 mm. Now I'm just waiting on the new shims to arrive and it should be road ready again. I stripped the crappy black spray job off the tank and I'm in the process of painting the other plastics graphite gray. Think I'm going to leave the tank bare for now, I like the burnished aluminum look.

This winter I want to strip it down to the frame and get it blasted and coated, couple spots of rust in places. Don't know what to do about the wheels and fork sliders, they're all heavily oxidized. I'd love to hear peoples opinions about painting the wheels, the rear is a drummy.


See my build thread here:
http://www.motobrick.com/index.php/topic,8732.0.html
  • Northern Virginia
  • BMW K75T

Offline Martin

  • ^ Quintessential Motobricker
  • Posts: 4475
Re: New Brick in NoVA
« Reply #1 on: August 06, 2016, 03:53:15 PM »
Welcome to the asylum you will  be sure to get lots of hints tips and opinions.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline TimTyler

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Re: New Brick in NoVA
« Reply #2 on: August 06, 2016, 04:17:12 PM »
The exhaust was super tight, measured 0.215 mm.

That's not that bad, but it is out of spec. You're only one shim size off (right?)  :dunno

As for the hesitation off idle, unplug the throttle position switch temporarily and I bet the hesitation goes away.

Offline Shiny

  • Motobrick Curious
  • Posts: 49
Re: New Brick in NoVA
« Reply #3 on: August 06, 2016, 04:18:48 PM »
My calculated shim size was 2.00, which has me worried because future adjustment won't be possible...

The TPS was unplugged when I got the thing and it ran then. Is there any reason to have it connected anyway?

See my build thread here:
http://www.motobrick.com/index.php/topic,8732.0.html
  • Northern Virginia
  • BMW K75T

Offline TimTyler

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  • Posts: 1884
Re: New Brick in NoVA
« Reply #4 on: August 06, 2016, 04:21:38 PM »
What sized exhaust shims were installed?

Was the exhaust gap 0.215 mm on all three cylinders?

Offline Shiny

  • Motobrick Curious
  • Posts: 49
Re: New Brick in NoVA
« Reply #5 on: August 06, 2016, 04:25:22 PM »
Since you're kindly offering to double check my math... (I'm an engineer who hates math and likes beer in the garage)

Intakes:
1 - btwn 0.127 -0.152 with a 2.65 shim
2 - btwn 0.102 -0.127 with a 2.70 shim
3 - btwn 0.152 -0.178 with a 2.65 shim

Exhausts:
1 - btwn 0.203 -0.229 with a 2.60 shim
2 - btwn 0.203 -0.229 with a 2.50 shim
3 - btwn 0.203 -0.229 with a 2.60 shim
  • Northern Virginia
  • BMW K75T

Offline TimTyler

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Re: New Brick in NoVA
« Reply #6 on: August 06, 2016, 04:32:37 PM »
Looks to me like you only need -0.05mm on the exhaust valves to be sure you're in spec.

Somebody please correct me if I'm wrong.

Offline Shiny

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  • Posts: 49
Re: New Brick in NoVA
« Reply #7 on: August 06, 2016, 04:38:17 PM »
So here is my math:

  • Northern Virginia
  • BMW K75T

Offline TimTyler

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Re: New Brick in NoVA
« Reply #8 on: August 06, 2016, 04:45:12 PM »
Here's my exhaust math.

0.30 specified gap
0.23 current gap
0.07 difference

0.05 is one shim size and will make the gap 0.28 which is between the spec range of 0.25 and .030.

Offline Shiny

  • Motobrick Curious
  • Posts: 49
Re: New Brick in NoVA
« Reply #9 on: August 06, 2016, 04:51:31 PM »
Crap. This is why beer and math don't mix. Where did my math go wrong? The intakes look okay?

Plan was to put these on the intakes.
1- 2.50
2- 2.35
3- 2.7
  • Northern Virginia
  • BMW K75T

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