BMW K bikes (Bricks)

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1Back to top Go down    Oh FFS-old K's!! on Tue Nov 17, 2015 2:32 pm

Motorbike Mike

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Some weeks back I bought a very cheap but complete 1996 K1100lt SE because I wanted a 16v engine for my flying Brick. It came with both panniers and top box too.



I agreed with the owner £450 and he even delivered it!
It rode OK, gearbox, final drive and electrics all ok so I gave him the money and off he went-probably grinning from ear to ear.

I started to strip it and it became clear that it had had a harder life that I'd thought.





I had a real job getting all the bodywork and electrics off. It fought me all the way, it was determined not to come apart. 3 broken exhaust studs in the cylinder head-I thought I was lucky!





I got the bike down to the bare rolling chassis and thought my troubles were over but a the front right engine mounting bolt broke in the crank case.





I tried stud extractors but broke it in the bolt. It was obviously superior quality because I drilled through the broken end-yes, I really did.



I drilled and drilled thinking I'd have to use a nut like the other side. I used larger and larger drills until the final 8.5mm drill snagged and it pushed the remaining threads out the other side. Lady luck smiled upon me this afternoon. The drill went dead centre of the bolt which obviously helped.






I ran a tap down to clear the rubbish and there wasn't any aluminium or steel in the flutes of the tap.




Perfect wouldn't you say?


My tip is, if you get frustrated, walk away, drink some tea, coffee or alcohol and go back later, it's worth the patience.
It's taken me a week. Very Happy

The motor's now off for a full refresh including hot cams, internal lightening and as much off the head as we can manage to get some compression into the thing.

It's going in this-8 valves aren't enough for a track K.

    

2Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 3:15 pm

Kyle10

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Head shaving. Interesting. 
I work for an engine remanufacturer and I've been toying w/the idea of shaving the head of my 2V, as the equipment, techs and shop are at hand. Inviting disaster untold or is this a viable route for a bit more oomph? How do you determine acceptable tolerances?


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1985 K100rt 0052183
1983 Honda VF750 007713 
    

3Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 3:25 pm

92KK 84WW Olaf


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I suspect is quite achievable on the 2V, it has crossed my mind as I have access to a head specialist [one who doesn't wear a white coat for Kpox]. But if you have the older cylinder head from the leaded petrol as opposed to unleaded engines I would think twice. As far as I see these cope fine with unleaded petrol but not sure how they would stand up to the higher compression ratio. No idea on how the fuelling system copes with it though.


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 81,400miles
    

4Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 4:31 pm

Motorbike Mike

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@Kyle10 wrote:Head shaving. Interesting. 
I work for an engine remanufacturer and I've been toying w/the idea of shaving the head of my 2V, as the equipment, techs and shop are at hand. Inviting disaster untold or is this a viable route for a bit more oomph? How do you determine acceptable tolerances?
The reason I'm skimming the head is because there aren't any higher comp pistons readily available and as life's short, I'm not spending weeks on end looking for pistons to suit. Valve timing will also need compensating due to slightly shortening the chain from crank centre to cam centre
As for tolerances, valve to piston will be the vital statistic that must be observed. We think that the combustion chamber shape should be OK.

    

5Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 4:36 pm

92KK 84WW Olaf


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I don't have the answer to this but.....are K75 and K100 pistons identical and if not are they interchangeable? Maybe a check on part numbers? The compression ratios differ but I don't know if this is due to head design or piston design or both...

Inge where are you?


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 81,400miles
    

6Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 4:41 pm

Motorbike Mike

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@92KK 84WW Olaf wrote:I suspect is quite achievable on the 2V, it has crossed my mind as I have access to a head specialist [one who doesn't wear a white coat for Kpox]. But if you have the older cylinder head from the leaded petrol as opposed to unleaded engines I would think twice. As far as I see these cope fine with unleaded petrol but not sure how they would stand up to the higher compression ratio. No idea on how the fuelling system copes with it though.
I'm thinking that the 16v1100 motor will be fine as they are all fit for unleaded fuel.
I've managed to suss out that you can easily add fuel with the M tronic but you can't take it away.

    

7Back to top Go down    Re: Oh FFS-old K's!! on Tue Nov 17, 2015 4:45 pm

Motorbike Mike

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@92KK 84WW Olaf wrote:I don't have the answer to this but.....are K75 and K100 pistons identical and if not are they interchangeable? Maybe a check on part numbers? The compression ratios differ but I don't know if this is due to head design or piston design or both...

Inge where are you?
You're right about the higher comp K75 pistons. You can fit them into a K100 8v, my current spec Flying brick has K75 pistons.
The 8v pistons aren't suitable for the 16v engine and, the 1100 engine has another 3.5mm on the bore.

I'm in Sheffield.

    

8Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 12:21 am

K75cster

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yes 10.2 for the 100 and 11.0 for the 75 so that 8 points on compression should make a stock K pleasant, but as always much more is needed to make a racer go hard and stay hard the length of the main straight.


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

9Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 1:43 am

Kyle10

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I've managed to suss out that you can easily add fuel with the M tronic

Well earned knowledge, I'm betting. Willing to elaborate?


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1985 K100rt 0052183
1983 Honda VF750 007713 
    

10Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 5:27 am

dee why

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My mechanic (the previous owner of my bike) rebuilt the engine with K75 pistons about 40000ks ago.

That's it, I'm out of my mechanical depth now.

Cheers,


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Dee Why

04/86 K100 VIN 0009479 Columbia Silver
    

11Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 7:42 am

92KK 84WW Olaf


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@Kyle10 wrote:I've managed to suss out that you can easily add fuel with the M tronic

Well earned knowledge, I'm betting. Willing to elaborate?

But.....is the Motronic for the 16 valve engine? 8 Valve has different LE Jetronic? 8V and 16V pistons won't be interchangeable due to the valve recesses in the piston crowns being different.

K75 piston upgrade seems an easy one.....my moles tell me this might possibly be done without removing the engine.


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 81,400miles
    

12Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 9:12 am

Motorbike Mike

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I've tried 16v Motronic but fueling is all over the place, I've had the bike on a dyno.
Because the Motronic is a very basic batch injection system, it delivers at a set rate and no lower but can be made to give more fuel.
I've looked at fitting a system from a GSXR1000 or similar but they have too many sensors to fit to a K motor.

    

13Back to top Go down    Re: Oh FFS-old K's!! on Wed Nov 18, 2015 7:34 pm

RicK G

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Way to go http://www.diyautotune.com/catalog/microsquirt-c-35.html?osCsid=8458fd523cc226b1d9a5c672b65b0329


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

14Back to top Go down    Re: Oh FFS-old K's!! on Thu Nov 19, 2015 5:03 pm

Motorbike Mike

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Thanks for that Rick, I've emailed them asking for a suitable kit.

    

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