- Bike: BMW R80 G/S, R100GS & M72 Sidecar, Gilera Runner ST200
Progress update – 3rd Apr ’18:
This is the difference between a 5% lower first gear & the standard one. Take a guess which is which.
How it works
The gearbox is now reassembled, shimmed, & buttoned up. Took me a few goes to get the assembly order right (heating the box, dropping in bearings, locating selectors, juggling the lay & output shafts, & then getting bearings to seat properly). Shimmed up nicely. It changed gears & is a freer turning box than Gus’s was post bearing replacement, so the shimming must be a little looser. Made a wee blue filling the box with oil while it was on it’s side on the work bench. Then I realised the oil was flowing out of the speedo drive.
I will reinstall the box in the next few days once I have a rolling chassis.
HPM triples & forks:
I’ve shortened the KTM250SX forks (I’ve put a video link below), but didn’t check on the bushes & seals yet. I figure that I will need to tweak things, so no point in changing these now. The fork springs are shortened 75 mm (which increases spring rate). I’ve also inserted an internal spacer in the cartridge / on the damper rod / above the top out spring, to reduce travel 75mm. So the forks notionally retains the 225mm R100GS travel, & should be in the ball park for sag pre the sidecar going on. The forks have 600cc 5wt oil per side, with about 110mm air gap. Actually much of the work (& spending) was done by Igormortis, & I’ve just finished it – but looks good for my application. The triples are set to mimic the stock GS offset, but the shorter wheel will reduce rake.
Here’s a link on how to shorten early open cartridge WP4860 USD forks
The triples were relatively painless to fit, as I had had John make me up a more robust steel stem (replacing the alloy KTM stem). This has a slightly looser fit on the top bearing. I’ll need to figure out how the instruments will mount. I’ll be using Gus’s light again, so mounting that is easy. BTW another set of HPM triples & a set of KTM open chamber forks are for sale on facebook for EUR850 if you are interested…The set up uses a Brembo Goldline calliper. Pads are equivalent of EBC FA244HH. I’ll have to wait to see if the brake is sufficient for the chair weight. If not I’ll buy another set of forks to get another left leg, so I can mount another bark calliper.
I’ve mocked up the bike with tank. Probably wont be the prettiest bike out there.
I’ve chosen the KTM forks because they are a leading axle, strong, & what I already had available. Should do everything better than what I had on the R80, & not have the slightly worrisome modified triples that the R80 had.
A stock KTM triple has offset 20-25mm, however the HPM triples were built for a BMW G/S on steroids – a G/S with bigger suspension travel. Offset is 38mm rather than 43, but otherwise…
Also, this will have an 18″ wheel rather than a 21″, so a reduction in rake, with the ability to tune somewhat in where the forks sit in the triples. So yes, still ‘too much’ trail, but better than the mono I was punting around before.
Confirmed rake with my set up is 28 degrees, & I’ve measured trail at 92mm, on the unladen solo bike, working with stock R100GS suspension travel, & without dropping the forks thru the clamps. Wheel radius 310mm.
Progress update – 8th Jul ’18:
Finally got a free afternoon to work on Gus, with an eventual view towards getting the sidecar operable.
Nothing major completed. Just pottering around. And no photos at eleven.
Fitted up the front sidecar mounts. The top front mounts sit where the front HPN tank mounts were (& the reason why that tank needed to move to the G/S). The bottom front mount is more problematic. The GS gearshift boss fouls where this needs to run. The back mounts will need to be fabricated once the bike is mobile.
Refitted the gear change linkage, & fitted the original (narrow) metal footpegs. I’ll look at replacing those with wider platforms at some later date (the pivot pegs Gus used to wear are now on the G/S).
I spent some time cleaning up the old G/S airbox. That had half a farm load of soil in it, along with a load of oil (the RT airbox that was on the G/S has the clean air solenoids & associated plumbing in it, so I’ve decided not to use that). Once the G/S airbox was clean, then I could refit the sidecar 40mm GS carbs (off the bent bike). No cableing yet.
Also cleaned up the stainless exhaust headers, & y-pipe, which had become quite discoloured.
I’ve had Mossrax make up a new stainless front brake line to fit the new calliper. Just need more time to make up some bracketry to hold that in place, then fit it.
Unfortunately a load of the good parts have gone into the G/S, or the (sold) R80 Mono. So much of the afternoon was spent scouring the tubs & boxes that hold the remains of the RT & G/S motor searching for missing parts, & making up a small list of things that need to be sourced or replaced in due course. Like the missing bolt & nut that holds the gearbox to the engine, which I cannot find for love nor money. Or a replacement for the one set of the exhaust clamp rings which were stolen for the G/S – (the G/S was missing one side when I got it) – I should have been able to replace that from the bent bike.
Gus is well on his was to becoming even more of a Frankenbike than he used to be, using parts from 12 other bikes:
– R100GS – Gus original frame, paralever, final drive, wheel & modified wiring loom
– R100GS – Bumblebee 24 litre tank
– R100GSPD – Engine, carbs, oil cooler, driveshaft, gearbox, & ignition switch from the bent bike
– R100GSPD – Seat from MarkS’s bike
– R80 Mono – Front axle, & starter motor
– R65 – horn & crash bar brackets
– R80G/S – Airbox, alternator, & diode board
– R100RT – twin Fiam horns, regulator, assorted small parts
– R1200C – front wheel & front disc. Front Tyre is OEM DR200 (quality) 😀
– KTM 250SX – shortened forks & fork guards
– YZ250F – front guard
– GSXR600 – exhaust can
Postscript. :clap Found the exhaust clamp rings, a better exhaust nut, & most of the small bits I was missing in another forgotten box. The gearbox/engine bolt & nut remains stubbornly lost
Progress update – 22nd Jul ’18:
It occurs to me that maybe I should have painted the frame before I started all of this reassembly work. :hmmmmm. Oh well, something to do – some other time.
While all the major components are in place, it’s making everything work together cohesively that is taking time. The final fixing of some bits that were just rush assembled in a dry run, to get things up to roller stage. Like the top triple clamp that was missed the top bearing shield. Or the non matched RHS spark plug cap (probably from the RT) that needed replacing. Or finding & recycling other small parts – like the rear brake cable adjuster off the bent bike – Gus’s original is MIA (no doubt I’ll find a small stash of parts after I clean up at the end of the project).
Also spent way too much time making brackets out of alloy angle, for the regulator, brake lines, & the heated grip relay.
When Mossrax made the brake line, the bottom banjo was angled, the top straight. I’ve swapped them around. The current set up is not ideal (for bleeding, quite apart from any other reason), but I’ve ended up putting the angled banjo at the top because the straight banjo fouled the barkbusters.
Also sorting the myriad of small issues like fuel lines, throttle & choke cables, & accessory wiring.
Sent off a spares order to Motorworks. Mainly for stuff that I couldn’t recycle from other bikes. Like final drive seals, new rear brake shoes, the rear brake cable, & another EI tail light (all for Gus). And a new clutch cable (for the G/S – the old one initially responded well to cleaning but is getting stiff again). Also ordered more oil filters from Kelvin in Blenhiem, & need a new rear tyre for the G/S (probably get in a Shinko 805). Mrs Box.a.bits will say that’s enough for now. There’s more stuff I should have ordered, but I’ll have to make do for an interim period. Like a seat cover, paralever pivots, & a mirror.
Managed to break my bigger torque wrench. No idea what happened there. It got stiff, & broke internally when I was dialling it down from setting the engine mounts.
Progress update – 29 Jul ’18:
Prototyped a new dash set up.
Also did some work cleaning up Mark_s’s old seat.
Longer term I am aiming to recover it with in a bumble bee scheme. I was putting the old cover back on, with an intention to (vinyl) paint it black. Now it’s on I have decided the red doesn’t look too objectionable (for an interim period anyway), so will leave it (Mrs Box.a.bits likes it).
Progress update – 4th & 5th Aug ’18:
Installed some new airhead jewellery – I’ve swiped the old EI LED tail light for the G/S.
The headlight & front guards creates a change in the perceived frontal dimensions.
Most of today’s work was getting the bottom brake line holder to work with the front guard. Originally that was supposed to go between the guard & fork leg. Eventually I made a slightly larger one to go outside of the fork guard. Also needed to dremel a cut out in the fork guard to allow clearance for the disc bolts (yes, it’s tight in there…).
The right side front guard can’t be bolted to the fork legs – the internal threads on the fork leg are stripped. I’ll need to get a helical kit in.
Made a stand-off for the instruments.
Progress update – 2nd Aug ’18:
How time flies. Slow but steady progress. Front brakes are now bleed & operational. Used an old R100 twin shock brake line stay, so that’s the 13th bike that has contributed.
Got some alloy standoffs made up, so the instrument brackets are bolted up properly.
9th Aug ’18:
Front indicators (Barkbuster LEDs) wired in. Front brake disc bolted up.
The Bosch Electro Magnet Alternator:
I’ve used Gus’s old motor & the Endurolast alternator in the G/S ‘Supertanker’, so I needed to come up with a stock alternator solution for Gus. That meant reinstalling the bosch electro magnet alternator, diode board, & regulator, & recreating some of the wiring I’d ditched in Gus’s earlier solo iteration.
To power up the alternator, I needed to either wire in a new 3w tell tale light, or use a resister to mimic the draw. On the stock R100GS, that light was part of the idiot tell tales within the instrument cluster, long since on-sold.
This light has 2 main functions:
– To show that the alternator was working, & as an indicator of the charging systems health. This function has already been met by the use of a Sparkbright LED voltmeter;
– To excite the alternator’s electro magnets. It does this as part of a circuit from the switched power on its way to ground. Above 1.5-2k rpm, the light extinguishes as the alternator powers up. The power cannot flow from the alternator back to the 3w bulb, as it is restricted in flow ‘direction’ thru the diode board.
I wasn’t keen on Padmei’s suggestion of the using the headlight park light – I use that instead of the headlight during the commute (albeit with a 21w halogen bulb in place of the stock 3w item).
Rather than bother with a bulb, I’ve gone down the resister route. That is documented here & in Snowbums article here. Effectively there are 2 paths people follow:
– To wire in a 330 ohm 5w resister in parallel to supplement the 3w pilot bulb, as a protection should the 3w bulb burn out, or;
where the 3w bulb is deleted completely, wire in a 47 ohm 5 w resister (which mimics the draw from the bulb).
– I’ve adopted the second option. I’ve run a bridging wire between the green/brown wire switched power from the alternator, thru the 47 ohm 5 w resister, connecting to the blue wire running down to the diode board. Checked Warin’s calculation using some of the excellent calculators on the net – spot on.
One area I need to wait for more real world experience on is how hot this resister gets if the ignition is switched on, but the alternator is not charging.
Progress update – 15th Sep ’18:
Shifted the heated grip controller onto another bracket under the tank, & mounted the grip heater relay off the other side of that same bracket.
Mounted the heated grip switch off the cross bar pinch bolts on the handlebars.
Reinstalled the battery, turned the key, no apparent shorts (so that’s good – right?), dash lights up, indicators work (front’s are wired the wrong way round -Doh!), lights work, engine turns over on the starter motor, so far, so good. :thumb