BMW K bikes (Bricks)

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1Back to top Go down   My custom build Empty My custom build on Fri Mar 08, 2019 8:34 am

diwhy

diwhy
active member
active member
Hi all! Im pretty new to the forum and working on bikes.

I started this project just before winter, not sure how it will end up.
But I want it to clean up airbox, exhaust and some other stuff
My custom build Receiv10
 My custom build Img_2010My custom build Img_2012My custom build Bmwk1010
My custom build Bmw_k111



The idea I had for the Air box removal was:
Keep the original AFM
Build a custom manifold from the AFM to the engine.
I have a really shitty drawing of it( sorry i know its really bad) but if will give you the general idea.
What do you guys think ? 
The whole point is to get some space between the fuel tank and the engine.
Do you guys think it will give enough air? What other mods should I do if it ends up this way? Do i need to re-calibrate the AFM ?
I dont care much about fuel efficiency or losing some horsepower/toque, but I dont want to damage the engine or any other part. 
  

My custom build Luft_i10
Thanks guys and gals!

    

2Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 10:59 am

duck

duck
Life time member
Life time member
The stock air filter (way oversized for a 1L engine) is a very good filter.  Getting rid of the intake air box and putting a cone filter on the MAF has been done successfully by many before but whatever cone filter you use will probably let more dirt through.  This won't damage your engine outright but it may cause it to wear more/faster.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

3Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 11:31 am

diwhy

diwhy
active member
active member
Hi

Thanks for the reply. 
I have given that some thought and planned to put on multiple filters.
It wont eliminate the problem I assume, but maybe reduce it a bit.

https://unifilter.com/about/uni-product-line/#street-bike-clampon

    

4Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 1:46 pm

chris846

chris846
Life time member
Life time member
What you've sketched up there is a manifold, whereas the OE item serves as a plenum chamber too. I don't pretend to understand the fluid dynamics in its design, but I do expect that it has a significant effect on how the engine runs. 
For starters, inside the OE plenum are a set of intake runners - tube extensions to the individual throttle bodies. The length of these is designed to place peak torque at an optimum place in the rev range. The volume and shape of the plenum is also designed to maximise the positive effects of the various sound waves that resonate along the intake runners.

I guess a bike would run with a manifold like the one you've designed, but it'd be interesting to see how well.

I got rid of the OE plenum on my K75 Madass, but I tried to make the replacement so's it would maintain the OE parameters (volume & intake runner length). Like you, I accepted that my shed guesswork would take the engine away from its optimum horsepower and torque, but I was also concerned about the effect of unmanaged pressure waves on the flapper valve of the AFM and the consequent problems with fuel mixture. This is problem you wouldn't have so much on a N-alpha FI system, such as fitted to the 16valve engines.

Have fun experimenting.


__________________________________________________
The Longest Lunch
    

5Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 2:06 pm

duck

duck
Life time member
Life time member
Sound waves?  I suspect the intent of the plenum design is to equalize pressure across the TBs as well as having the flow be laminar or turbulent to whatever extent maximizes how well the air and fuel mix to promote the most effective combustion.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

6Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 2:20 pm

Laitch

Laitch
Life time member
Life time member
@diwhy wrote:Hi all! Im pretty new to the forum and working on bikes.
Please click on the Profile tab in the header of the Forum page. In the next screen that appears, click the Signature tab then enter your moto's model and year. That information will then appear at the bottom of all your posts to let readers know what you might be riding, restoring or repairing without having to backtrack to find out.


__________________________________________________
1995 K75T 73,000 miles
My custom build Usa-lo10
    

7Back to top Go down   My custom build Empty Re: My custom build on Fri Mar 08, 2019 5:55 pm

charlie99

charlie99
VIP
VIP
@chris846 wrote:What you've sketched up there is a manifold, whereas the OE item serves as a plenum chamber too. I don't pretend to understand the fluid dynamics in its design, but I do expect that it has a significant effect on how the engine runs. 
For starters, inside the OE plenum are a set of intake runners - tube extensions to the individual throttle bodies. The length of these is designed to place peak torque at an optimum place in the rev range. The volume and shape of the plenum is also designed to maximise the positive effects of the various sound waves that resonate along the intake runners.

I guess a bike would run with a manifold like the one you've designed, but it'd be interesting to see how well.

I got rid of the OE plenum on my K75 Madass, but I tried to make the replacement so's it would maintain the OE parameters (volume & intake runner length). Like you, I accepted that my shed guesswork would take the engine away from its optimum horsepower and torque, but I was also concerned about the effect of unmanaged pressure waves on the flapper valve of the AFM and the consequent problems with fuel mixture. This is problem you wouldn't have so much on a N-alpha FI system, such as fitted to the 16valve engines.

Have fun experimenting.

well thought out chris My custom build 112350


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OMy custom build Au-log10

"redframe" rs "bitsa"  with many contributions from the k100 community ,,with many thanks
    

8Back to top Go down   My custom build Empty Re: My custom build on Sat Mar 09, 2019 12:32 am

duck

duck
Life time member
Life time member
Just to add a little of (my) perspective here:

The bikes we ride are heavy, old tech machines.  Giving up a few HP to make a custom whatever-you-want isn't really that big of a deal.  If you really want to go fast there's tons of bikes out that will give you a ton more torque/speed for only a few grand.  You can pick up a used K1200RS, Gixxer, CBR or Busa for not too much that will eat a classic K bike for lunch.

And experimenting is half the fun.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

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