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101Back to top Go down    Re: K75 Madass on Wed Jan 31, 2018 2:01 pm

chris846


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Hiya Barry and thanks for the encouragement. I know that I've always enjoyed reading threads about other people's builds, so it's good to know that a few like-minded folks have got something from reading about my own bit of metalwork. It's all good fun and I know that we all tend to work at the same level, with the same sort of facilities (or lack of) so there's a lot of empathy out there.

I can't believe how generous the legislators are in the UK - that some dumb amateur like me can stuff a sixty horsepower engine into an overgrown garden gate, sling on a pair of wheels, and go tearing up the highway just yards from unprotected pedestrians. It's great to think that this sort of real freedom exists, when lots of people get hot and bothered about governmental control and restrictions.

Motorcycling eh? It's much more than just bikes isn't it?



Last edited by chris846 on Thu Feb 08, 2018 6:06 pm; edited 1 time in total

    

102Back to top Go down    Re: K75 Madass on Wed Jan 31, 2018 4:12 pm

chris846

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Re. K-Fest
Donington is only just down the road for me, compared with you intercontinental lot. If you (Olaf & Co) are approaching on the A5 from the West then I'll maybe extend my run and join you along the way - in my head it's a lovely fine day...

It's only an hour to Donington for me, so I don't know if I'll be stopping both nights. I'll keep an eye on the K-Fest thread and if it looks like there'll be an evening get together for kayistas I'll look for some accommodation (or if the guy who's got my tent and Trangia reads this...)

cheers

    

103Back to top Go down    Re: K75 Madass on Wed Jan 31, 2018 7:55 pm

92KK 84WW Olaf

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I'll keep an eye on the K-Fest thread and if it looks like there'll be an evening get together for kayistas I'll look for some accommodation (or if the guy who's got my tent and Trangia reads this...)

With us travelling there is ALWAYS a get together. Dinner on the Saturday night at the Nags Head for the K yakers is being talked of by Frank Miles who I have met and I have been talked into bringing Kristmas puddings for all. It has become a tradition.

Best get your tent back.  I have allocated space in my tent to Will Crean but we will have the makings of tea and coffee and I think there may be a space for your tent..... as I have already asked.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

104Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 4:27 am

chris846

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If you like reading, here's the build report I prepared for the MSVA examiner (he didn't bother reading it - it turned out not to be that sort of examination!)

BMW K75 – VIN XXXXXXXXXXXXX – Submitted for MSVA test 23/01/2018

The vehicle is submitted as a Class D Motorcycle; an Amateur Built Vehicle, constructed wholly by the owner/person submitting for test. I am that person and I am not, nor have I ever been involved in any business where motor vehicles are constructed or assembled.

The motorcycle uses a secondhand engine/gearbox/drivetrain from a BMW motorcycle. Its main feature is a frame of novel design, made by the owner/builder. The remaining parts are secondhand or new items sourced from other motorcycles, the aftermarket, or made/adapted by the owner builder.


Christian XXXXXXX



Concept:

To build a custom motorbike, based on the style and appearance of the Sachs Madass scooter:



Owner/builder:

Retired motorcyclist, previous professional experience in small engineering/design/fabrication, with access to a basic workshop. Previously (1996) built a Q-plated trike with a custom triangulated frame/chassis and a car engine. Experience of motorbike and car mechanics, electrics, maintenance and adaptation.

Donor motorbike/engine:

The engine/drivetrain is from the BMW K series of motorcycles in production from 1983 until 1995. The K series featured a novel layout 'Compact Drive System' (CDS) using a car-derived in-line 4 or 3 cylinder engine canted 90' to the left and mated to a single plate dry clutch in a bellhousing fitted to the rear of the engine block. The bellhousing rear face forms the mounting for a gearbox, the rear face of which incorporates the forward mountings for a hollow single-sided swingarm containing the driveshaft. The swingarm terminates in a bevel drive unit with a four stud, car-type mounting for the rear wheel. The CDS uses high-strength magnesium alloy castings for the various components, which all bolt together to form a very strong drive 'module'. The driving forces associated with the rear wheel are all catered for within the CDS. This particular drivetrain was chosen for these advantages, plus the owner's familarity with the K series motorbikes. The 750cc 3 cylinder variant was chosen because the 'missing' cylinder allowed for a shorter wheelbase (BMW achieved the 1000/750cc versions by effectively removing the front cylinder, retaining a high level of parts compatability between the two versions).

Example picture showing the CDS of a K100 4 cylinder variant attached to a standard frame:



Donor engine year of manufacture: engine no 753EA 38864014

The complete engine and drivetrain for the project was bought as a secondhand spare, with no accompanying documentation regarding the identity of the original vehicle. A web resource decodes its engine number as follows:

1st & 2nd characters: 75 = capacity (750cc)
3rd character : 3 = number of cylinders
4th & 5th characters: EA= federal emission code (no further information re. this)
6th & 7th characters: 38 = week of manufacture
8th & 9th characters: 86 = year of manufacture
10th-13th characters: 4014 = engine number

The engine therefore was manufatured week 38 of 1986. Some of the details of the engine (colour of casings, plug lead & coil type) seem to confirm that the engine is an 'early' one.

The original frame (not used on the project bike) consists of little more than a brief set of comparatively unbraced tubes to support the seat/tank etc. The exception is the braced steering head. The frame bolted to the CDS in five places: two front, two aft, and a fifth, assymetric connection at the mid-point, which braced the frame against the loads from the rear suspension top mounting. A layman's assessment of the frame is that the frame takes its strength from the CDS, not the other way round.

New frame – concept & construction:

A completely new frame was devised to reproduce the two striking features of the Sachs. These were the in-frame fuel storage which removed the need for a conventional tank, and the 'Y' frame layout. The profile lines of the 'Y' were considered important and were followed as closely as possible: the main stem following a straight line from headstock to rear wheel hub at an approximate inclination of 30', and the seat stem following a tangent from the top of the front wheel at an inclination of 10'.

Thanks to the layout of the CDS, these requirements could be satisfied with a reasonably simple frame. The main stem consists of two parallel 90mm diameter 3mm section steel tubes (rolled hollow section) spaced 50mm apart and plated top and bottom (3.0mm plate). These are boxed and internally gusseted (3.0mm plate) to a conventional steering head at the front. The rear/lower part of the main stem is formed as a yoke which sweeps around the ancillaries (starter, battery, alternator) to the rear CDS attachment points on the gearbox casting. This gives near-enough the desirable headstock-swingarm straight line in profile. The yoke is constructed from 100x50x3mm rolled hollow box section. The seat stem also serves as the rear suspension top mounting point, plus a support for the silencer. It is constructed from two halves of 76x3mm tube (rolled hollow section) spaced apart to complement the appearance of the main stem. The seat stem/main stem junction is substantially gusseted and braced to cater for the cantilvered loads. The entire frame is available to store fuel, except for the headstock, the right hand leg of the yoke and the seat stem which contains the electrics. The frame was built to a jig and professionally TIG welded by a specialist welding firm.

The frame attaches to the CDS at the original frame mounting points, with the exception of the redundant mid-point mounting. At the front the frame is attached via two short stays made from thick-wall cold-drawn seamless tube. At the rear the yoke/main stem terminates in mounting lugs. The main stem, the front stays, and the engine/CDS form three sides of a triangle when viewed in profile.

The disadvantages or compromises in this design are the limited fuel capacity (an intentional sacrifice of function for form) and the weight due it being constructed from steel with a deliberate tendency to guess/err on the side of caution in the absence of any facility for stress analysis or calculations. The overall wet weight of the bike is 208 kg, which is around 30kg lighter than a standard unfaired K75, but still quite heavy for the type of bike it is intended to be. Replacing the frame with an aluminium version would be an ideal improvement.


Pictures showing the tacked-up frame prior to finish welding and the application of the upper and lower plates to box in the main stem (the seat stem is not yet fitted):







Frame/steering geometry:

The geometry is conventional. The project bike is intended to have 'medium' handling for comfortable and stable road riding. The wheelbase was designed to be slightly less than the somewhat lengthy 1516mm of a K75. This was achieved by setting the distance between the front wheel and the front of the engine on the project bike to be the same as a standard K100. When BMW conceived the K75, they 'simply' omitted the front cylinder of the K100, which left the standard K75 with an 'engine-to-front-wheel' gap increased by approximately 78mm over the K100 (78 mm is the pitch of the omitted front cylinder). The project bike redresses this by moving the engine (and the connected drivetrain/CDS/rear wheel) forward by this amount. 50mm of this is then added back to the wheelbase by the inclusion of a 50mm spacer between the rear end of the swingarm and the bevel box. The overall reduction to the wheelbase is therefore approximately 25mm, bringing it to 1490mm.

This offers three theoretical benefits to handling and rideability: a reduction of wheel base to a more mainstream value and better weight distribution (the finished bike is almost exactly 50/50 front/rear) Lastly, the increase in swingarm length (the 50mm spacer) is akin to something BMW themselves went on to pursue with the paralever rear suspension as a means of addressing the bikes excessive tendency to 'jack' at the rear when accelerating.

The rake of the project bike is 27.5' which replicates the K75 and is a fairly mainstream figure for a street bike. A departure is that the project bike uses the forks and yokes from a KTM duke2 motorbike. This machine (an agile middleweight dual-purpose bike) has a steeper rake of 26.5' which offers the sort of sharp steering associated with KTM's dirt bike heritage. However, the KTM yokes give 109mm of trail at 26.5' of rake, whereas the standard K75 yokes have much more offset and give just 101mm of trail at 27.5 degrees of rake. Overall, the 'sharper' trail of the K75 offsets its lazier rake, whereas the lengthier trail of the KTM contains its 'twitchier' rake. The standard K75 is considered to have quite a low trail amongst similar motorbikes and the 'S' version of the K75 had a steering damper fitted, which is normally associated with innate steering twitchiness. The comparatively agile steering geometry of the K75 might have been BMW's attempt to compensate for its lengthy wheelbase. The project bike adopted the KTM's 'front end' as a safer and more conventional starting point, but with rake increased by 1 degree to give it a steadier feel. Trail (calculated) is increased to approximately 112mm as a result. The trail is quite large, but is expected to be acceptable on a bike with the wide handlebars (and leverage) of the project bike. When it comes to steering geometry the general acceptance is that even the best calculations and predictions will always succumb to trial and error and the feel of a bike when ridden. The above design figures were conceived to do no more than place the project bike somewhere in the safe middle ground, prior to being actually ridden and evaluated.

Departures from standard – engine:

The engine remains as standard, with the exception of the car-type alternator which was replaced with a suzuki item that better suited the space constraints imposed by the new frame. The assymetric frame mounting point (for frame rigidity) has been eliminated from the bellhousing since it was no longer required and fouled the layout of the new frame.

Departures from standard – fuel system & ignition:

The fuelling and ignition system (Bosch LE-Jetronic) is completely standard, with the exception of the airbox/plenum chamber, where a bespoke item was necessary to cope with the space constraints imposed by the new frame.

Departures from standard – exhaust:

The standard 3 into 1 header is used, with a new midpipe (same bore as original, but longer) to suit the revised layout. A standard, E-marked silencer from a CBR600 Honda is used, with an altered inlet pipe (to suit the fact that is is actually upside-down!). Neither the original bike (1986) nor the project bike had/have any catalytic converter fitted. The Bosch engine management system has no facility for this.

Braking:

All components of the rear braking system are standard K75 items (with the exception of the braided steel brake pipe).

The front braking system is a hybrid of twin Brembo P4 65mm calipers (sourced from a BMW F800) that are equivalent to the items that the KTM/White Power forks were designed for. These operate on 320mm front discs sourced from a BMW R1100 bike (similar weight, greater power). The discs are mounted on bespoke rotor/adaptors made to a tested design. The master cylinder is a Brembo 16mm item (sourced from a Ducati) which is correct for the calipers.

All braking items were stripped and rebuilt with new parts where necessary.

Wheels:

The wheels are from the uprated K100 16v variant of the K series bikes. The wider rim sizes allow fitment of more up to date radial tyres which offer a huge improvement to roadholding and rideability.

Lighting:

Lighting is conventional (front/rear position lamps, number plate lamp & telltale lamp operated from a single switch, plus a main beam with high/dip-and-telltale facility). The lamps were bought online, from manufacturers who offered them with E marking (whether or not this has any meaning!).

A 'parking' lamp (i.e. can be safely left on with the key removed and bike locked) is not fitted.

Hazard flashers are not fitted.

A fog lamp is not fitted.

No auxilliary lamps are fitted.

Unauthorised use:

I'm not sure if I've managed to interpret the regulations correctly. The bike has a 'key' which must be inserted in the normal way to make an electrical connection and switch the bike on and start the engine. It also has a separate device to prevent unauthorised use. This is in the form of a proprietary motorbike immobiliser that is wired to interrupt the fuel injection circuit. The alarm/immobiliser is activated by improper activation of the bikes electrical circuits (voltage drop sensing) or by movement of the bike.

There is no steering or transmission lock.

Stand:

The sidestand retains the standard K75 retraction mechanism that operates when the clutch lever is pulled. I.e the stand will retract automatically before the bike can be ridden off in the normal manner.

No centrestand is fitted.

    

105Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 4:45 am

charlie99

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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

106Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 10:32 am

Barry in IN

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Let me repeat myself by saying again how much I like a well executed plan as opposed to a hack job.  You've sure given us an example of the former.


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1992 K75s
    

107Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 11:24 am

Chocolate

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Great handwork and well done paperwork.
Not many will do so.

You deserve a Yorkshire pudding ;-)

Cheers


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Only a few activities make me experience my senses in a way motorcycle riding does, it is like swimming in the nude in a river.
K75 BA/1992 ABS, K75 BA/1991 noABS, Ducati, Mobylette M1/1973
    

108Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 12:50 pm

chris846

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Cheers fellas, thankyou.

(Chocolate - I AM a Yorkshire pudding, or did you know that?)

Did some last little bits of welding on the frame today (if you squint when you weld a petrol tank, does it protect you?) and I've just taken the tank, wheels and other bits for powder coating. 

Decided on a metallic anthracite for the frame/tank - it's a car wheel colour apparently and they use a clearcoat to give it a gloss. S'nearly black I suppose...

    

109Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 1:06 pm

Two Wheels Better

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@chris846 wrote:Did some last little bits of welding on the frame today (if you squint when you weld a petrol tank, does it protect you?) and I've just taken the tank, wheels and other bits for powder coating.
The safety squint!? been doin' that for yonks.
 Wink


__________________________________________________
1987 K100RS, Big Block '93 K11/K12 hybrid, '09 K1300GT, '07 K1200R, '04 R1150RT, '95 R100 Mystic, '77 R75/7.
Have we accomplished half of what we dreamt we would? There may still be time.
    

110Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 1:26 pm

chris846

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Lol

    

111Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 1:36 pm

Two Wheels Better

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Back in OZ some years back we bought the 17 year old lad a Madass, got it home, rode it round the back garden, then he got his licence and rode the thing all round north coastal NSW and SE Qld. It was a vibraty, sluggish thing, and bits fell off or came unscrewed with regularity. One day I took it out on the M1 near Coolangatta and tapped it out at under 90kph, imagining a bigger cylinder & piston, carbie and pipe. This creation of yours just blows all of that away and I am glad to be following your progress.


__________________________________________________
1987 K100RS, Big Block '93 K11/K12 hybrid, '09 K1300GT, '07 K1200R, '04 R1150RT, '95 R100 Mystic, '77 R75/7.
Have we accomplished half of what we dreamt we would? There may still be time.
    

112Back to top Go down    Re: K75 Madass on Thu Feb 01, 2018 10:10 pm

Woodie

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Haven't chimed in until now Chris but I have been following along the whole time and want to thank you for a great thread.  You deserve to be very proud of a great build.  You've built a Badass with Balls is what you've done!  My son watches these Youtube clips that begin with 'How it should have ended...'  Echoing TWB a little, I think your build is how the original should have ended.

Looking forward to some ride reports.

Cheers, Andrew


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1985 K100RT
52667
    

113Back to top Go down    Re: K75 Madass on Fri Feb 02, 2018 3:37 am

chris846

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Hiya Woodie
It's great to think that there's some guys dotted all over the world who get something out of reading this thread. 

I really appreciate everyone's kind words. The bike is pretty much stripped down now, I'll post some detailed pics of the build up and the parts I've had to make.

Have a great day!

    

114Back to top Go down    Re: K75 Madass on Fri Feb 02, 2018 4:18 am

92KK 84WW Olaf

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Looking forward to seeing this one at K Fest!!! Best of luck with the finishing details, it sounds an awesome bike. The wet weight isn't bad either. As you said, aluminium frame is probably the only other weight saving option.

When my friend built his car years back he used stock mechanical and electrical components like you have done so that maintenance was straightforward. Even his glass panels were stock. His manual which he also wrote for it was amazing, listed the manufacturers, model, part nos etc.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

115Back to top Go down    Re: K75 Madass on Thu Feb 08, 2018 5:53 pm

chris846

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Been to the powder coaters....


It's metallic anthracite, with clearcoat. Depending on the light it looks anything from primer grey to deep gunmetal. Not sure. What it does do is make the frame look 'believeable' i.e. I look at it and think "did I make that?".


The above pic shows the yoke detail: the 2 hole mounting for the petrol pump on the far left, the gusseting between the seat rail and the main tube, the (blanked off) 4-bolt mounting for the fuel sender in the middle, and the 2 cap screws where the VIN tag goes. The thick-wall tube at the top of the pic is the rear suspension top mount.


The above pic shows how the relay/electrical compartment is formed between the 2 seat rails, also an inside view of the gusseting. The rectangular hole is a duct for the wiring to pass down towards the engine/gearbox/battery/starter/alternator etc.



This pic shows the underside of the frame. From the left: the rear mounting lugs that attach to the gearbox, the fuel outlet (on the LH leg of the yoke), the bottom opening of the wiring duct, the 2 mountings for the front stays, inbetween them is the inlet for the fuel return from the FPR, and a lug for the radiator top mounting.

And this humungous doohickey breaks the scales at 49lb, or 22.2 kg. I've worked out that if make an equivalent in aluminium, doubling up the wall thickness (no science here), then it'll weigh about a third less.

    

116Back to top Go down    Re: K75 Madass on Thu Feb 08, 2018 6:37 pm

chris846

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Never mind all this tofu-eating, tree-hugging anthracite nonsense, here's some good old Henry Ford:


These are the front stays that link the frame to the engine front mountings. Nothing is original (Kenny Howard) and this idea came from the r-series bikes. The view is from the rear, so the bottom pegs are for the OE radiator support rubbers, the 2-bolt flange on the right is for the coolant expansion tank, and the short flange below it is for the FPR. The small lug on the top LH flange is actually a blanking screw in a threaded hole for a clip to hold the main loom.

And this is a butchered side stand. The main bracket is now three quarters of its former self, and the leg has been straightened and cut down on the end.


This last picture is the alternator bracket/battery tray, which mounts on the 4 original battery tray mounting holes. The bracket is necessary to mount the soozooki alternator. The 'shot full of holes' appearance is my attempt to kid myself that it's an efficient, lightweight design, when the truth is that it's just a half-hearted, ineffective effort with a half inch drill. Lipstick on a pig.

    

117Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 5:01 am

charlie99

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just stunning work chris ...sheesh I cant even weld ...but gives me ambition to learn the craft

the paintwork certainly details the clean attention to detail , no wonder the tests through the registration and safety accreditation could only show minor issues to be resolved .

wow !!!!!

thanks for the pics  and explanations


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

118Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 5:42 am

92KK 84WW Olaf

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@chris846 wrote:Never mind all this tofu-eating, tree-hugging anthracite nonsense, here's some good old Henry Ford:


These are the front stays that link the frame to the engine front mountings. Nothing is original (Kenny Howard) and this idea came from the r-series bikes. The view is from the rear, so the bottom pegs are for the OE radiator support rubbers, the 2-bolt flange on the right is for the coolant expansion tank, and the short flange below it is for the FPR. The small lug on the top LH flange is actually a blanking screw in a threaded hole for a clip to hold the main loom.

And this is a butchered side stand. The main bracket is now three quarters of its former self, and the leg has been straightened and cut down on the end.


This last picture is the alternator bracket/battery tray, which mounts on the 4 original battery tray mounting holes. The bracket is necessary to mount the soozooki alternator. The 'shot full of holes' appearance is my attempt to kid myself that it's an efficient, lightweight design, when the truth is that it's just a half-hearted, ineffective effort with a half inch drill. Lipstick on a pig.

Lipstick on a pig?

Designed by a Muppet?

I think not.

K Fest....As for us travelling on the A5, if you have the time and inclination we plan on having lunch somewhere along the way on the A5. Out of Holyhead 11ish so lunchtime might work. At the moment we look like we are a group of 7, 6 Ks and a lady rider on a ZZR1400 called Bambi that is proudly described as having 2 lady owners.

If you are riding naked weather will play a part.....


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

119Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 6:30 am

chris846

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"If you are riding naked...."


been a while, been a while..

    

120Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 8:13 am

92KK 84WW Olaf

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@chris846 wrote:"If you are riding naked...."


been a while, been a while..

I figured.....the reference to lipstick on a pig. Sounded like a reference to the Muppet Show.

Anyway I think your sense of humour will ensure you fit right in.

Now, having gone and put a new Remus exhaust on the K1100 I went out in the rain on Wednesday. All looked good but when I got home the rear end was messed up with road dirt way worse than the RT does. I have figured the cause out and decided to make a diffuser to attach to the centre stand so when it is up will prevent this and direct the spray away from the bike.

Just wondering will you find something similar in our climate.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

121Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 8:49 am

Ringfad

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For Olaf



Have you got part number 11 as they are not always fitted


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   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 51K Km     ;BMW; K1100RS Red 1993 70k miles  ;BMW; K100 16V Black (ex ElectricMonk)
    

122Back to top Go down    Re: K75 Madass on Fri Feb 09, 2018 9:16 am

92KK 84WW Olaf

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Simon,

I do and am thinking part no 11 could be the cause of the problem.....I think it creates negative air pressure behind it drawing in the crap.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

123Back to top Go down    Re: K75 Madass on Sat Feb 10, 2018 8:09 am

chris846

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Hugger, yes. I did a very short journey on the project which involved going along the only road in and out of our village (road closures) which is currently adjacent to a building site, and it was raining. I couldn't believe the amount of grit that got everywhere coming off the back wheel. With the bike of doom being open like it is, all those holes on the top of the engine block just got filled with crap. A hugger was on the list of things it could hopefully do without, but I think that's been revised...

Problem (sorry, 'challenge') is how to mount it - world's number one bike stylist here has routed the wannabe Ducati exhaust inconveniently between the back wheel and the swingarm. I've put a bid on a mystery hugger that Motorworks are selling on ebay (currently 5 quid - fingers crossed), which looks like it could be adapted to mount off the rear caliper (Ilmberger favourite) or maybe the swingarm extension block...

Here's what I was doing yesterday:




The little stub in front of the hole for the filler cap is the tank breather. The orange sealing ring is a mystery item from the oddment box - perfectly dimensioned! 
The second picture is, I have to be honest, just bling. Those shiny 3-hole whatevers are 'supposed' to be knee grips but I think if I found myself in a situation where I was having to rely on those, I'd be better off calling it a day and jumping off (again).
The third picture is just the tank outlet. I'm not keen on powder coating around things that need to seal - it can be uneven, it tends to chip, and even if it doesn't chip the petrol (in this case) can seep between the metal and the coating causing it to lift. A bit pedantic of me, but I had time to grind the mating faces back to metal and put a thin layer of primer on instead.

    

124Back to top Go down    Re: K75 Madass on Tue Feb 13, 2018 3:14 pm

chris846

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And here's what I was doing today!

This is the CDS all cleaned up ready for the rebuild.


Here's the altered coil mounting. The top lug was removed and replaced with a brazed on lug. The bottom lug was shortened. This was done so's the coils can mount 90 degrees rotated - necessary to clear the new frame. The second pic shows the coils installed - on the standard bracket with one lug removed.



This pic shows the front frame stays in position and the relocated FPR. The radiator top mounting lugs have been removed - I thought they'd be classed as 'projections' for the MSVA test. (I try not to butcher 'valuable' parts, one day someone might need this radiator to keep a K75 on the road).


And here's the loom installed. It's clipped along the inner throttle body brace. I didn't want it on the underside of the frame/tank where I thought it would look untidy. I've tried to keep it as clear from the engine as I could - time and miles will tell! The main gubbins of the loom is ready to be fed up through the duct in the frame when it's installed.

This pic also shows the alternator bracket installed.

    

125Back to top Go down    Re: K75 Madass on Wed Feb 14, 2018 3:24 pm

chris846

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More rebuilding..

Here's the fuel outlet/strainer, it's a standard item from a Mercedes. The female thread in the tank (M36 x 1.5) is actually a nut that I turned down. I thought I was being smart and saving myself the cost of buying a tap, but the thread got a little burned during welding and so I ended up having to buy a tap anyway. I also had to buy another strainer to replace the one that I butchered trying to screw it into the duff thread. Doh. That's one expensive outlet.



Here's the plenum and AFM installed. The AFM is mainly supported by its outlet stub that sits in an O-ring bore in the side of the plenum. There's also a (really crummy) bent ally bracket that you can see (only the good bits of) in this pic. This fastens to a nylon adaptor/inlet which the air filter clamps onto.



Here's a pic showing the complete intake. The 'english poo' 90' bends are still there, but painted black to hide their humble plumbing heritage. Fools no-one I suppose. They are only good for 60'c but seem to be holding up so far. Plan B (if needed) is to replace them with an equivalent made from superior plastic.



Here's the extended alternator shaft. Or wine goblet as I now realise it looks like. The front part is the OE alternator flange, and the rear is a bit that came with the suzook alternator. The second pic shows it installed - the 4 prongs are for another set of cush drive rubbers. It's cushioned at both ends, see, I really don't care!


(Edit: not sure why a battery needs a 'Danger - Paedophiles' warning sign on it?)


The last pic shows the alternator installed. The mounting bolts have short spacers sandwiched against the alternator body. This is MK2. MK1 didn't have these, and the alternator was a dead fit in the mounting bracket. MK1 was impossible to assemble...

    

126Back to top Go down    Re: K75 Madass on Thu Feb 15, 2018 2:57 pm

chris846

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Not sure about the colour.
Installed the frame today, not sure about the colour at all. It's not bad, it just looks like an old man dull colour. That hurts, because I am an old man. Not quite buying my clothes at the beige shop just yet, but getting there.




I've bought a spare cam cover and crank cover. Maybe polished, or black with the polished ribs, would that work...?

    

127Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 6:24 am

92KK 84WW Olaf

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Good idea to have the spare covers. I love satin black and silver as in polished ribs. The covers are cheap enough to experiment with and if the satin black isn't best looking for you it would sell on.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 80,700 miles
    

128Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 1:42 pm

chris846

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Hi Olaf, I think you called it with the satin black/polished covers. These arrived today. 



I gave the cam cover a quick run on the polisher, but they need a refurb. Any ideas on the best way to do this? Paint stripper/shotblast/rattle can/stove enamel..?

    

129Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 4:22 pm

Crazy Frog

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This is looking fantastic.
Great job.


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1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

130Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 4:46 pm

charlie99

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satin black is my 2 cents

the original paint is difficult to lift with just paint stripper . but worth a shot on a small area to start with

good luck


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

131Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 6:53 pm

chris846

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Hiya Crazy Frog
So where am I going to put....THE STICKER!

    

132Back to top Go down    Re: K75 Madass on Fri Feb 16, 2018 8:21 pm

Crazy Frog

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@chris846 wrote:Hiya Crazy Frog
So where am I going to put....THE STICKER!
Looking closely, I can see a lot of similitude between your frame and the logo.
I should have put your name on the logo. Very Happy Very Happy


__________________________________________________
1986 k75, 1985 K100rt, 1985 K100rt/EML sidecar.
    

133Back to top Go down    Re: K75 Madass on Tue Feb 20, 2018 3:17 pm

chris846

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Space reserved for the sticker.....

Anyway, yesterday I spent mainly destroying fuel sender units. It was one of those days. The MK3 sender started leaking (I shortened it and the potting compound that I used seemed to have reacted with the seal, causing it to swell and crack the plastic body) so I decided to replace it with one that was the correct length to start with. Trouble was, the only correct-length item I could find on ebay (from a Aprilia Scarabeo 500 - what on earth is one of those?) was for sale in Latvia, and cost 4 times as much as all the others.

Anyway, it arrived and on it went. And the gauge didn't work. The sender has got an ingenious damping facility - the float sits inside a plastic tube chamber with just a tiny hole at the bottom and a tiny hole at the top - slows down the rate at which petrol can flow in/out of the float chamber. Too slow for the project bike I'm afraid, so I reached for the driller (fitted with nice sharp new drill) and set to with much less patience than was appropriate. Drilled through the plastic body okay, but didn't stop there and drilled straight through the resistor track inside. Dumb ass.

Threw the expensive, Latvian MK4 in the bin and found another sender unit - a humble-looking refugee from some sort of scooter. This was a 500 Ohm unit, but fortunately the speedo of doom has 2 programming options for the fuel sender -and 500 Ohm is one of them! The cheapo sender even came with a choice of 2 signal wires - 500 Ohms when full, or 500 Ohms when empty. How good is that!

This was a good old float-on-a-stick sender, so even I couldn't destroy it whilst modifying it to fit inside the frame/tank. In it went (its doormat-sized rubber gasket didn't leak) and it works fine. 

Of course, owing to it's location it reads 'full' at anything above 2.5 litres, and 'empty' means there's just half a litre left (what's the mpg on a K75?).

That was an entire day's effort. 

More...

    

134Back to top Go down    Re: K75 Madass on Tue Feb 20, 2018 4:20 pm

chris846

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Here's the thing after a bit more of a productive day today:


Been polishing again. The angled piece with the loom poking through is the first part of the headlamp/speedo bracket - it uses 2 mounting holes on the underside of the KTM upper yoke. The black nylon piece fixed to the top of the lower yoke is the lower mounting.


This is the next piece: the plate-with-a-big-hole-in-it is the headlamp support and it pivots on the upper pin that you can see partly inserted (you can't see the pivot block, but it's held in with the 2 screws you can see on the front face of the angle bracket). The springs-and-knurled-gubbins at the bottom give it a bit of adjustment for the beam aim.


The sideplates and speedo binnacle installed...


Tomorrow is a day off. Meeting up with a couple of old friends. Neither are motorcyclists, Jeez I don't want to bore them. They're so nice, they'll ask how the project's going. I'm allowing myself a two-word answer: 'nearly finished!'.

Then they'll say; "what are you going to do with it when it's finished?".

    

135Back to top Go down    Re: K75 Madass on Mon Feb 26, 2018 2:43 pm

chris846

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Carried away with the polishing. Maybe it's because after years of never teaching myself how to do it properly (thinking you can stuff any old piece of rough nonsense on the wheel, with whatever compound is to hand, press on for all you're worth...etc.) I've finally got some sort of hang. The results would probably make a professional wince, but they look shiny enough to me.

Here's the seat/scaffold clamp:

Installed:

And an hour's work on the silencer:


Big problem today. Tried to fire it up after fitting the silencer. Cranked (and cranked and cranked and cranked - you know something's wrong and it's not going to fire, but you carry on and kill the battery too, like you really need that extra problem...) but didn't fire. Checked the fuel return - no fuel being pumped! 

Decided that the reason was probably the immobiliser that I'd placed in the FI relay circuit...the immobiliser that was still on the bench!

Of course, this also explained why the oil pressure light didn't seem to be working - I'd fed its 12v from the FI circuit too - so's an extinguished lamp would be a means of indicating when the immobiliser contacts were open!


Dumb dumb dumb ass!

    

136Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 7:37 am

Dai

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Sounds like the old Japanese problem of still cranking when the killswitch is off. Stupid design of wiring loom that was and they all did it! Every bike that came through my hands had the loom modified so that the killswitch killed the starter button and all of the idiot lights too. I have no idea how many grateful batteries owe me their lives. Or how many owners cussed me because they couldn't figure out why nothing was working.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

137Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 2:59 pm

chris846

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Talking of killswitches..

What's the connection between a killswitch and a baboon's a*se?

(had some plastikote cherry red left over after repainting the kill switch)



I think that's a definite 'no'.

    

138Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 3:01 pm

chris846

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Or maybe the world is ready for the first ever case of gorilla-bike rape?

    

139Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 3:20 pm

Ringfad

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It is a Monkey bike :-)


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   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 51K Km     ;BMW; K1100RS Red 1993 70k miles  ;BMW; K100 16V Black (ex ElectricMonk)
    

140Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 4:07 pm

chris846

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141Back to top Go down    Re: K75 Madass on Tue Feb 27, 2018 7:48 pm

Dai

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You walked right into that one. I'm just pissed off that I didn't think of it.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

142Back to top Go down    Re: K75 Madass on Wed Feb 28, 2018 9:57 am

Gauntlett

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Hi Chris, I was interested in what you did to the MAF filter intake and the type of filter you are using. I really want to change the arrangements on my K100 trike could you provide more details and pics of your arrangement please.

    

143Back to top Go down    Re: K75 Madass on Wed Feb 28, 2018 3:23 pm

chris846

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Hi, it's just an adaptor plate made up from nylon - I think it was a piece of 25 or 30mm plate that I put in the 4-jaw and turned a boss half way along it, then trimmed the remaining bit of plate down to suit the 4-bolt flange mounting on the AFM. The filter is just something from the Ramair catalogue with the right sized stub.

Which I gave myself a little old pat on the back for. But then all my smartarse points got completely wiped out when I came across this just the other day! (ebay item number 271327231394)



eBay item number:
271327231394

    

144Back to top Go down    Re: K75 Madass on Wed Feb 28, 2018 3:54 pm

chris846

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Anyway, after a very weird experience in the safari park, which made national news and Pornhub on the same day, here's a safer version..

    

145Back to top Go down    Re: K75 Madass on Thu Mar 01, 2018 6:33 am

Woodie

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Why lookee there!  Even sitting still that beast is so cool it pops a wheelie  


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1985 K100RT
52667
    

146Back to top Go down    Re: K75 Madass on Thu Mar 01, 2018 3:28 pm

chris846

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Here's a bit of detail from the coolant filler cap. The original filler stub didn't work out with the frame/tank, but my understanding is that I have to stick with the OE cap. This needed a bit of surgery on the filler neck, and a two part adaptor stub that sandwiches it:




I seem to have had a bit of trouble with filler caps over the years - they start leaking below the set pressure. I've never been able to work out whether it's the seals on the 'suck and blow' valves deteriorating, or the springs weakening. Never had any luck trying to fix them. Never found one that doesn't leak a tiny bit either. Is there a good fix for these?

    

147Back to top Go down    Re: K75 Madass on Thu Mar 01, 2018 7:04 pm

Dai

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@chris846 wrote:Is there a good fix for these?
Don't use one? Razz


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

148Back to top Go down    Re: K75 Madass on Fri Mar 02, 2018 3:26 pm

chris846

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How does that work, do I keep my thumb over the hole or something? (I can do that - it's not under the tank anymore - I'm happy to try...)
scratch

Very Happy

    

149Back to top Go down    Re: K75 Madass on Fri Mar 02, 2018 3:51 pm

charlie99

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I had issues with the bmw filler cap also chris
and found as the bike was purchased  the inner seal rubber was not fitted , more likely lost at some point

operation seemed normal until heavy traffic riding and near over heat conditions

out on the highways was always ok

my fix was a simple oring of the correct size on the filler cap that took up the gap between the inner core of the cap and the neck of the filler tubing down tube ...maybe 1.50 rather than the 6 or 7 dollar bmw part ...that does expand and fall off (over time )  in any case they get lost pretty easy and pretty easily unnoticed


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

150Back to top Go down    Re: K75 Madass on Sat Mar 03, 2018 2:11 pm

chris846

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FINISHED!



Couldn't resist doing the rear hub cap to finish it off - seeing as there's a bit of a '3' thing going on with the design.

    

151Back to top Go down    Re: K75 Madass on Sat Mar 03, 2018 3:05 pm

charlie99

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just stunning chris


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

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