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Box'a'bits 08-22-2010 02:10 AM

The rehabilitation of Sir Gustave Sabastian (‘Gus’)
What’s this thread about:
I’ll use this thread to document my rehab, ongoing development, maintenance & riding of Gus. Hopefully we’ll get a community of GS / airhead owners here.

This is what Gus looked like when I bought him in Jul 10.

And the second picture shows what he looked Jul '13.

<table style="width:auto;"><tr><td><a href=""><img src="" height="532" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href=" eat=embedwebsite">2013-07-21 Castlehill Rd, Puketoi Rd, Bideford</a></td></tr></table>
Why ‘Gus’?
Gus is a bastard in a number of senses. Old vehicles need names. Cursing a thing just doesn’t seem right. It’s always a bitch or bastard. And Gus is positively geriatric.

Why I bought Gus:
I’m a long time airhead fan, having owned a ‘78 R100RS, (there's a separate thread on that now), ‘83 R80ST, ‘86 R65, & an ‘88 R100RS. In the ‘90’s my wife & I travelled Europe on the ’78 RS. We spent about 3 yrs alternatively working in London, then travelling the summer months. The trip back home was supposed to be an extended tour through Africa. I actually purchased the ST for that trip, bought a Acerbis 43L plastic tank for it, but alas it was not to be. I wrecked the RS when a van did a u-turn on me, and then the couple we were to go with had a head-on with a minicab. The consolation prize was a trip to the South of France, & then home. Both the RS & the ST were imported back to NZ, but in a moment of madness I sold the ST to allow the purchase of a lounge suite. Which is now almost dead…

I’ve had a couple of goes at getting a GS since, but this hasn’t really worked out. The last white RS was supposed to be one, & the KTM 640a was close (in a sort of ‘Paris Dakar’ way). The KTM was a brilliant bike, but my experience was KTM parts support was lacking. Whilst I am sure the whole package would do big miles, portions of the bike seemed to be higher maintenance then I am used to (Hi ClintNZ & Warewolf!!).

One thing I missed with the KTM was the ability to load either Katherine or Mandy on the back & to go out for a day trip. The KTM was really a one person bike.

<table style="width:auto;"><tr><td><a href=" edwebsite"><img src="" height="534" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="">2009_1 02742nd</a></td></tr></table>
Airhead GSs have been on my Trademe favourites list a long time now. I’ve seen a few cheaper GS’s come up (Newguy, Barrie & Padmei). Padmei, you don’t know how lucky you are to have your bike. My finger hovered over the buy now for quite a while the night before you bought it…I have finally decided that I needed to build the bike I had lusted after for 20 yrs.

So where is this heading?
I have agreed with Mandy that I can spend the proceeds of the KTM sale on Gus. Given where the NZD has been against the Euro, GBP & USD I decided to buy some of the larger items now rather than wait. So I have ordered a bunch of parts from Motobins to allow repair of Gus & the RS, Touratech pannier racks & a 43l Tank (I like big tanks & I cannot lie...), to change the handlbars & risers, & have ordered an Ohlins shock from Robert Taylor at CKTechnical. Robert's price has been comparable to import (before freight & GST!), but I get the shock build to my specs.

The wishlist is somewhat more advanced.... :thumb

To make this thread a bit more manageable I have started & will expand on an index - green text are links. For much of the maintenance & modification I haven't always included links, largely because this happened over a number of posts or pages & may be predominantly text.

Index of Maintenance
- Replacing the carb throttle pivot o'rings
- Replacing front wheel bearings
- Do you need to improve your R100GS rear brake? How?
- Replace a spoke in the rear cross lace wheel
- Fork oil replacement (standard forks)
- Discussion of Emulators in standard GS forks
- Replacing a head gasket & replacing the camchain
- Re-ringing Gus, & putting in 9.5:1 Pistons. Part one / Part two
- Replacing the rear Main Seal, & Oil Pump o'ring
- Breaking into the gearbox Part 1, Part 2, Part 3, Part 4, Part 5, Part 6
- Replacing the battery

<table style="width:auto;"><tr><td><a href=" website"><img src="" height="600" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href=" site">2014-02-02 Top of the South Trip</a></td></tr></table>
Index of Modifications:
- List of modifications / upgrades to date
- Shifting the oil cooler from the crash bars
- Fitting the HPN Tank
- Nissin 4 Pot Brake Conversion
- Fitting Pivot Pegs
- 48mm KYB fork conversion
- Discussion on replacement sidestands
- Discussion of Emmulators in standard GS forks
- Wiring in resistors to remedy hyperflashing indicators
- Fitting a Baja Designs 8" headlight unit & a Trailtech Vapor Speedo Unit
- Hardhead rocker cover protectors (replace crashbars)
- Modifying the rear brake pedal to improve leverage, & therefore braking capacity
- Changing to the exhaust back from a two into two, into a two into one - using a SV1000 left hand muffler
- Carb float bowl breather mod to give a higher wading depth.
- Replacement LED Tail Light
- Getting a replacement Rego Plate
- Building a front wheel (new Excel Takasago Rim & spokes) & servicing the forks
- Servicing an HPN oil cooler thermostat

<table style="width:auto;"><tr><td><a href=" mbedwebsite"><img src="" height="800" width="600" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href=" edwebsite">2014-09-07 Cold Kiwi &amp; 42nd Traverse</a></td></tr></table>

Index of day trip ride reports:
- Odlins Rd diversion. Akatarewas, Nth Island
- Sutherlands Hutt (Aorangi Forest Park), May '11, associated video clips - South Wairarapa, North Island
- Takapari Rd (Nth of Palmerston North) Jul '11 - Ruahine Ranges, North Manawatu, North Island
- Ocean Beach Ride Aug '11, & ICU breakdown. South Wairarapa, North Island
- Ocean Beach in the Rain - Wairapara Sept '11
- The Ride Of The Steves - Sutherlands Hutt & Ocean Beach, Wairarapa Nov '11
- Ocean Beach 2 up with Mandy Boxing Day '11
- Ocean Beach with Shewolf NZ, 2nd Jan '12
- Ride into the Mangatooks, Kapiti Coast, 4th Jan '12.
- Dusty Butt Pre Ride - Glendhu & Flat Point, Wairarapa, 15th Jan '12
- Two Fatties & A Skinny Take On Odlins Rd (Waiotauru Rd - an ex logging road / track) - Akatarewas, 4th Feb '12
- Ocean Beach with EddieB - South Wairarapa April '12
- MAD (Makairo, Aikitio, Dannevirke) Wairarapa, 30th Sept '12
- Odlins Rd, Akatarewas, Upper Hutt, North Island. 25th Nov '12. Fell off, broke some ribs, punctured a lung...
- Ocean Beach 26th May '13. Back in the saddle again...
- Ocean Beach & Onoke Spit 6th June '13 with Manakau_KTM (Wayne)
- Hinakura Rd, Riversdale Beach, Castlepoint Beach & Pack Spur Rd (paper road), Wairarapa 30th June '13
- Castlehill Rd / Puketoi Rd (non maintained road) / Daggs Rd - Bideford. Wairarapa 21st July '13
- White Rocks & Tora, South Wairarapa, 1st Sept '13
- Sutherlands Hut & Onoke Spit 20th Oct 13
- Takapari & North Range Road (North Manawatu, North Island) 16th Nov '13 . It must be November, I've broken some ribs again.
- Glendhu & Admirals Rds, Wairarapa. Dec '13.
- Rimutaka Pylon Track & Ocean Beach 22 Dec '13
- Visiting (but not riding) Pukemanu Adventure Ride, Martinborough, South Wairarapa, 23rd Feb '14
- Sutherlands Hut Track, Aorangi Forest Park, South Wairarapa. 26th April '14
- Martinborough / Riversdale Beach / Puketoi Rd, South Wairarapa. Sun 4th May
- Takapari Rd, Ruahine Forest Park, Pohangina Valley, 1st June '14
- Puketoi Road & checking the Makara Track, North Waiararapa 27th July 2014.
- Not the Distinguished Gentlemans Run - Wellington, Oct '14
- White Rock Station Ride. South Wairarapa. Dec '14.
- Ngawi, Batchelor Seal Colony, Cape Palliser & Ocean Beach, Wairarapa. Dec '14
- R-twin Works open day. Feb 15. Awahuri (Manawatu).
- The Panzer Brigade attack on Odlins Rd. 1st April '15, Akatarewas. Maybe we should have paid more attention to the date...
- North Range Road, Manawatu. 22nd May '15.

<table style="width:auto;"><tr><td><a href=" mbedwebsite"><img src="" height="600" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="">2 013-10-28 Cape To Cape</a></td></tr></table>
Index of multi day ride reports
- Cold Kiwi Sep '10 - Central Plateau, Nth Island
- 42nd Traverse, Old Whanga Rd, & Kiwi Rd Nov '10 - King Country, North Island
- Clarence River Reserve Feb '11 here, here, & here. Kaikoura East Coast Sth Island, & Reefton, Sth Island
- Easter Trip Away Apr '11, North Island - Taumaranui, Whangamomona, Taupo, Lake Waikaremoana, Gisborne & back to Wgtn
- Cold Kiwi, Old Whanga Rd, & the 42 Traverse Sept '11 & here. Video of the 42nd rockwall here. Central Plateau & King Country, Nth Isld.
- WAR. Waiouru Adventure Ride, Waiouru Miltary Training Grounds, Dec '11. Day one, day two, & day three
- RRRR 2012 (Round Ruahine Range Reversed (Part One) & Part Two - 24th & 25th Mar '12
- East Cape Airhead Ride, East Cape North Island, 20th - 23rd April '12. Days Three & Four here.
- MMMM 2012, July '12, East Cape North Island
- Aborted Cold Kiwi attempt Sept '12
- Cape to Cape ride. Cape Egmont to East Cape, 25th - 28th Oct '13
- Top Of The South Ride - 29th Jan to 2nd Feb '14. Rainbow Station & Molesworth, including the Lake Sedgemere to Severn Track. Edwards Pass. Braeburn Track, Porika Track & the Maruia Saddle. Clarence River Reserve. The Molesworth.
- The MMMM 2014. 15th & 16th Aug '14. The Ride Up & Day One, Day Two, & the Ride Home
- Cold Kiwi 2014. 5th-7th Sept '14, Horopito, Central Plateau, North Island. Ride Up, Cold Kiwi Rally & the 42nd Traverse, The Ride Home
- Cape to Cape 2014, North Island NZ, Oct '14. The ride there & day one. Day two & the ride home
- Bannockburn Bike Week. South Island NZ, 24th Jan - 8th Feb '15. Part One - Wgtn to French Pass, Nelson, Murchison (Maruia Saddle), The Rainbow to Hamner Springs. Part Two Hamner to Clarence River Reserve, then down to Ashburton, Part Three Ashburton to Cromwell. & The Nevis, Part Four Thompsons Gorge Rd, Hawksdun Loop, The Old Dunstan Rd, Track from Alexandra to Cromwell, Part Five Mt Difficulty, Cromwell, to Home, via the West Coast & Nelson.
- Central Plateau Weekend, North Island, 20th-22nd Mar '15, North Range Rd & Takapari Rd (Manawatu), to Taumaranui (King Country). Part Two Central North Island, Fishers Track, 42nd Traverse, Part Three, Old Whangamomona Rd, & Aotuhia Station
- North Island Invasion of the South 3 (NIIS - 3) 1st-4th May '15. Top of the South Island, based at Reefton. Porika Track, Braeburn Track, Mt Rochfort, Denniston to New Creek, Days One & Two. NIIS (3) Days Three & Four, Big River Mine, Waitahu River Track, Maruia Saddle, Braeburn Track, Mangatapu Track

<table style="width:auto;"><tr><td><a href=" mbedwebsite"><img src="" height="600" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href=" site">2014-02-02 Top of the South Trip</a></td></tr></table>
- What really dumb things have you done in the garage
- Airhead Philosophy
- Link to the CC Products performance upgrade article (twin plugging, compression increase & rejetting an Amercian GS)

<table style="width:auto;"><tr><td><a href=" e"><img src="" height="534" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="">2011-12-09 WAR</a></td></tr></table>

Oaters 08-22-2010 02:28 AM

Steve's Blog
nice post Steve - certainly a fashion among Kiwi ADV members to create their own blogs - a trend started by MarkS and since adopted by Bart & Padmei (there may be others) - good on ya anyway - looks like the restoration of your R100GS will be an interesting and hopefully rewarding project - have fun Cheers Aslan:freaky

Box'a'bits 08-22-2010 02:30 AM

Gus's History:
I purchased Gus from Rob in Whangamomana. Gus has done some miles - 198k kms (or 124k miles). First registered in 1991, & owned by BMW as a demo, then through two Rental Cos. Then 3 private owners: a father & son; then Rob. In the two years of Rental Co ownership, they racked up 160k, which I take to be a good thing. Hopefully long miles, & regular servicing. Maybe mature renters.

Initial Impressions
Looks-wise, Gus is almost a twin of Padmei’s R80GS, but is the R100 variant. Given the mileage there is some damage, but nothing that time, patience & money can’t fix.

Rob used the bike for adventure riding, and had a heavy fall on the right side at some point. He’s repainted the crash bars, but not the right rocker box cover, which is very battle scarred. He demolished the screen too. There is a dent in the right top of the tank, which might pop out with a bit of air pressure. He had made an engine bashplate, a new screen (clear Perspex, well shaped), & also a new stainless collector box (now well dented – no rear bashplate). He’s replaced the alternator rotor & the timing chain. No other history provided.

I have ridden him a grand total of about 100 meters, from Rob’s garage to the trailer, & from my trailer into my garage.

The shock seems ‘tired’. There is some rust starting on the left fork leg, between the triple clamps. The neutral light doesn’t work. The oil pressure switch seems like it has a seep. Oil weep near the sump gasket. The rear light has been broken & glued. The rear indicators have been replaced with smaller variants. The rear subframe paint has suffered from Rob’s top box (removed at sale). The swingarm / frame boot is perished.

The motor (on start up) was one of the quietest I have ever encountered (but an indication of valve lash being too tight). Idle was smooth. No noticeable issues with the driveshaft or gearbox. Tank shows some overspray. Repainted crashbars already mentioned. Tyres looks good in the Trademe pictures, but are actually munted. Rob sure enjoyed those corners round Whanga…

First job – valves
Intially I was really pleased with the color of the left plug. But the right side wasn't as good, & investigation showed the left carb to head rubber wasn't done up - so the jug was lean as a result of the air leak. Things that make you go 'Hmmmm'.

Adjusting valves are really a piece of cake BUT… someone has been over enthusiastic with the locknut on the left side. I’ll replace. Also the rocker cover central stud. I see this has already been helicoiled once. Also while I’m down there someone has bent the fins on the exhaust nuts trying to get the nuts off. I’ll need to replace that.

The Exhaust Nut doesn't look too bad in this photo, but that's because I've already managed to roll it 45 degrees. Believe me, its very sad. To the extent that the exhaust nut spanner doesn't fit anymore. Butchery

Endurolast Alternator
I bought this for the RS because I got tired of the limitations of the stock system. Here's a link to the Enduralast site.

On the stock system, I'm up to my third rotor, & second diode board replacement. I’d upgraded the mechanical regulator in London to deal with a commute I was doing, & had also upgraded the wiring.

I’ve now swapped the Enduralast across to the Gus. The stock system will go on the RS.

Starter Motor:
Valeo starter motors have a reputation for the magnets becoming un-glued. Also, sometimes they become noisy when they don't disengage immediately from the flywheel. I already had the starter motor out, so I decided to pull it apart to clean it up as much as possible. There is a lot of good info at Joergs website & also Anton Largiarder's. Stephen Bottcher actually epoxied between his magnets, so that if the glue on one failed, it would be held in by the others.

The 1st photo shows the top of the starter motor off. The 2nd has the actual motor detached, & the solenoid not yet disassembled. Basically I just cleaned & reassembled.

Unfortunately when I bolted the starter on the block, I managed to drop a nut down into the flywheel area (it was already in a socket I was about to use - who put that there?...). Oh well, I needed to do the clutch splines anyway!!. And the neutral switch isn't working, and the easiest way to fix it is to drop the gearbox..

bart-nz 08-22-2010 03:21 AM

Nice work Steve. I'll be watching with interest, as I'd like a project like that. It might be a decade before I get the time/cash though.

Off topic, but was that you who out bid me for that DR rear sprocket today Aslan? :evil

Padmei 08-22-2010 12:46 PM

:clap :clap :clap

Good stuff Steve. Yay now I can compare notes.
What are the limitations you talk of with the stock alternator setup? Output not enough to handle running a few appliances or parts just don't last long?

Have you got any pics of the top of your bike with tank & seat off? Just want to compare.

Dino3310 08-22-2010 02:38 PM

Very cool mate, will be watching with interest

Box'a'bits 08-22-2010 05:57 PM


Originally Posted by Padmei
What are the limitations you talk of with the stock alternator setup? Output not enough to handle running a few appliances or parts just don't last long?

Photo of the top of the bike as requested. Looks just like yours, down to the manky wiring. But the variances are for the Enduralast Alternator

The stock alternator output is 280w at best, but can deteriorate if the wiring / connections are allowed to corrode. The alternator takes to about 3k (?) revs before it actually even covers the engine & light load. This is problematic if you are in slow going or commuting. It relies on the red dash light to excite the charge circuit. If that fails, no charge. The diode board is in very hot / hostile environment - not the best for reliability. Stock grounding for the diode board is not great. A common fix is to run a ground wire from the front cover to a ground on the block.

BTW don't ever take the front cover off without disconnecting the battery ground - easy to burn out a diode from static charge if the cover scraps the diode board. DAMHIK.

There are work arounds for all of those issues.

The Enduralast not only makes more charge, it also starts charging earlier than the stock system. It's also a brushless unit (constant magnet), so potentially maintenance free. Have a look at the site, all will come clear.

My understanding are that the major differences between the two bikes ex factory are the carbs (you've 32mm, I've got 40mms), barrels & heads, & the final drive ratio (yours is a little shorter). That's pretty much it.

Mark_S 08-22-2010 11:23 PM

great thread Steve - between you Padmei and Bart (if he gets off his arse and takes more photos) this sites finally getting worth a daily visit.

so when is this monster going to finished so you can come for a ride .....?

don't forget to leave enough in the kitty for a trail bike or Andy and I will stop talking to you

Box'a'bits 08-23-2010 02:21 AM


Originally Posted by Mark_S
great thread Steve - so when is this monster going to finished so you can come for a ride .....?

don't forget to leave enough in the kitty for a trail bike or Andy and I will stop talking to you

Thanks for the kind words, Aslan, Bart, Padmei, Dino & Mark.

Mark, I need to have the bike up & running this weekend, so that I can get to the Cold Kiwi the weekend after. Hopefully the stripped stud in the rocker box cover won't leak (too much), because I don't want to take the heads off yet.

This week / weekend I'll strip the gearbox out (as a unit - I'm not that mechanically confident yet :rofl ) , lube the clutch splines, check the clutch plate for thickness, replace the neutral switch, grease the swingarm bearings, check the drive shaft bearings for play, and reassemble. I'll replace the drive shaft boot as part of the reassembly. Also do a fluids change (engine, gearbox, final drive). Oh & fit the racks, handlebars & risers, & the heated grips.

But it'll be a work in progress for a while after that. The big tank isn't due to be manufactured until mid sept, then needs to be shipped. Same for the shock. But with sufficient notice I'll always be up for a ride...:wink:

Need to get the RS up & running as well, so will effectively have two project for a while. Still dithering as to whether I should really sell that.

Mark_S 08-23-2010 03:03 AM


Originally Posted by BMWRSNUT
Mark, I need to have the bike up & running this weekend, so that I can get to the Cold Kiwi the weekend after.

Do you want some company for the ride up?

The klr has a whole heap of cobwebs all over it so I need to take it for a ride and blow them off

Box'a'bits 08-23-2010 03:11 AM


Originally Posted by Mark_S
Do you want some company for the ride up? The klr has a whole heap of cobwebs all over it so I need to take it for a ride and blow them off

Yes that would be cool. I'm going up Saturday, so 8.00am at the Waikanae Coffee Cart? I haven't made any choices re route yet.

I think Eddie's going up Friday, and intends to do a more relaxed run, over more varied roads...

Mark_S 08-23-2010 01:06 PM


Originally Posted by BMWRSNUT
Yes that would be cool. I'm going up Saturday, so 8.00am at the Waikanae Coffee Cart? I haven't made any choices re route yet.

I think Eddie's going up Friday, and intends to do a more relaxed run, over more varied roads...

subject to weather/work/family/health - see you at 8

route - don't care as long as its minimal main roads and involves a latte or two

Box'a'bits 08-25-2010 03:12 AM

Dropping the gearbox
Got a bit of garage time in tonight. Looking to drop the gearbox, so I can change the neutral switch, retreive a nut that has fallen into the flywheel area, and do a check & service on the back end of the bike

Dropped out the final drive bolts. Loctited in. Smelly gearbox oil in the driveshaft boot. The boot itself is perished & has a hole in the bottom. It'l be replaced.

Removed the shock as a prelim to removing the swingarm. Manufacture date is '93, so newer than the bike.
The driveshaft bearings look good & feel smooth - no apparent issues.

The swingarm bearings are a little dry, & one seal was loose.

It's been a pain getting the stainless collector box off. This needs to come off to give access to the gearbox. The collector box was homemade by Rob, and has taken a few fairly big wacks. It sits right up againt the engine sump, & covers the gearbox drain plug, so I'm fairly sure that the gearbox oil hadn't been changed in a while. The box removal required BIG leverage & heat to remove it....Its also bloody heavy. But I've no basis for comparison to the OEM.

Dropped the gearbox oil. NOT what I expected at all. It had WATER out first, then a reddish thin oil or ATF? Not the 80/90 weight I expected. :eek1 Very glad I haven't done any miles on this yet. I am hoping that the bearings are okay. I'll do the run the Cold Kiwi then change again. I need to swap the drain plug over with the RS, which has a magnetic one. Not sure what the current plug is - not standard BMW anyway.

Left the gearbox to drain, and will drop the gearbox out when I next get time.

XTC 08-25-2010 05:59 PM

Looking Good. BTW I'm loving the 640A :)

Padmei 08-26-2010 01:37 AM


It'll be interesting to see what happens when I replace my perished boot. I've read a lot of posts about finding oil in the boot - Eddie did too I think? Doesn't sound too bad tho. I guess it means replacing the seal?
Is that a big deal?

Are you using a manual 7 if so what one? i have the BMW one but more often I start taking things apart then look at it to see if there's something I've missed.

I will try to get mine back on the road when I locate a couple of brake pistons & then look at dropping the box & greasing the splines.

When you checked your driveshaft bearing, you just gave it a looksie & rolled it round checking for roughness? This all that's needed to check them out or is there a more extensive check?

Keep up the good work.

I wish a certain PD owner would just hand out all his extra bits to his mates:evil

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