Since the mighty DR650 has moved one to a new owner a new old bike has taken up residence in the garage.
Those who have ridden with me over the years won’t be surprised that I’ve gone back to an airhead BMW as this will be my 5th one.
It’s an ex-California USA bike so 32mm carbs rather the 40mm units the European bikes got and all the original US emissions stuff has long been removed.
This is one is basically stock and will largely remain that way, though It will probably get some 20mm bar risers and different footpegs but that’s about it at this stage.
I’ve been doing a few things to the GS
Discovering there’s Works Performance progressive fork springs in the front
https://www.adventureridingnz.co.nz/r100gs-suspension-identify-these-springs/
Changing the fork oil at 68,300 miles.
https://www.adventureridingnz.co.nz/bmw-r100gs-fork-oil-change/
I also changed the diff oil at 68,500 miles.
Last weekend I rebalanced the idle and the carb cables, just by ear as I don’t have a manometer at the moment. The idle only smoothed out slightly but the low end throttle usage made quite a noticable difference at small throttle openings.
I stuck a borescope camera down one of the spark plug holes of my R100GS cylinder to check which pistons my bike has. It’s an ex California model so I presumed it has lower compression flat top pistons, and this confirmed it does.
At 70,000 miles/112,000km you can still see the original factory bore hatching marks on the cylinder walls.
That’s a good looking bike
I really like my R80GS same colour but not as original
The bike is in the shop today for a WOF, fingers crossed.
In typical bmw airhead fashion I stopped at the gas station on the way to work and when I unlocked the petrol cap lock the lock mechanism came out with the key!
Woohoo, she’s wof’d and rego’d!!!!
Wow working on an airhead os so easy after the DR650.
I had the seat, side panel and rear shock off, lubed the upper shock mount and reassembled in 20 minutes!
Nice.I remember when Gus used to look like that….
Took the GS out today for a nice loop South from Tauranga along Oropi Road, which while being a sealed road and hence not ‘adventure’ certainly deserves an honorable mention, the southern end south of Oropi Gorge Road is tight and VERY twisty with bush right up to the road edge.
Oropi Road comes out on SH36 so I followed that down to Rotorua and had a noisey around town for a bit then the return trip was back up SH33 and SH2 to Welcome Bay Road.
That ran the first tank of fuel through the bike and I went onto reserve at 168 miles/269 km.
The tank is 24 litres total with 4.7 litres of that as reserve. so 269km / 19.3 litres = 13.94 km/l. That seems shocking.
My tank does have this weird flap in it though that’s quite a long way down the filler neck and stops you from getting quite a bit of fuel in. I suspect that might have to come out if I can do it safely so that I can fill that tank fully.
I also ordered some lower footpegs and bar risers a few days ago.
That flappy thing is often removed.
Given the fuel economy, the carbs likely need a rebuild. That said, I’ve never managed too much more on Gus. 15kms/litre is average. Phil used to get 17km/litre which I thought was exceptional. The thirst is one of the few downsides of airheads.
There is a bit of variability on the reserve straws, & often a bit of dirt at the bottom of the tank.Also the straws deteriorate & split over time. So don’t fully rely on the reserve range until you have checked it. Probably wise to carry a small fuel bottle until you have. Mandy was not impressed when we ran out of gas just outside Otaki on a stinking hot day back when I was running the stock tank on the sidecar.
My economy figure is a bit of a guess based on the tank size rather than an actual refil, and given I can’t get the tank filled up it should be a bit better than that.
Bling TIME!
BMW R100GS Lower Footpegs.
I found these footpegs on Ebay Australia marketed as fitting the F650GS/F700gs/F800GS. After some enquiries indicating that BMW didn’t change footpeg mounts between generations of GS models I thought I’d risk it and give them a try. They were selling at $80AU a set from MCMotoParts Store, plus shipping of course.
They are also available in Black or natural alloy.
The pegs use a common mount with a short bar and then the footpeg, the bar can be rotated around the mount, and the footpeg around the bar 360 degrees through 8 keyed positions.
In the position I’ve set mine up the footpegs are about 15mm lower than the frame mount and probably 40mm lower than the stock pegs, but they are also the same distance back from the brake and gear levers meaning aside from lowering the levers no modifications have been required, particularly to the gear lever.
Took the bike out today to test the new footpegs and they are working great, my legs are much more comfortable.
As I’m relatively new to Tauranga I’ve just been randomly exploring, this is Taumata Road which loops off and back on to SH36 only a short distance out of Tauranga.
I filled the bike up and got a true economy figure which is much more around average for an airhead.
I had a go at the funny flap in the fuel tank, termed a ‘flapendectomy’ in GS circles. The easiest way to deal wit the flap is to wedge a screwdriver against it and bend the hinge so that it stays open.
Before
This allows almost 3 extra litres to be put in the tank bringing tank range up to 300km’s.
After
I also fitted some bar risers in a mostly matching red. These ones raise the bars by about 38mm and move the bars back by 18mm and have made a huge difference to comfort.
I’m on the hunt for 1 of these calipers for a front brake upgrade, they were fitted to the BMW K100, R1100, R1150 and other models and are 1 half of a pair
The bike is filthy at the moment due to house renovations, lots of dust.
While my bike came with a flash Works Performance shock, it was well past it’s best. @Paul Greenslade was good enough to hook me up with a stock shock which is performing much better than the flogged out Work Performance unit was.
The bike also came with matching Works Performance front fork springs which don’t seem flogged out but are very harsh. The Works Performance spring is 595mm long with no spacer whereas the stock springs are 445mm with a 159mm spacer for the standard R100GS and 169mm spacer for the larger tanked R100GS PD. Michael Dobson at Two Cats Garage sorted me some stock springs for the front with a set of PD spacers so they went in today.
A new WOF sticker was stuck on the back last week and I was happy top hear the bike passed it’s check with no issues or advisories. It will need a new rear tyre sometime in the near future though.
While in the shop for the WOF the mechanic also took a rattle gun to the gearbox oil filler cap, I suspect whoever last did it up also used a rattle gun. I’d tried WD-40, a long bar and impact wrench and hadn’t been able to budge it. Now that I can open the filler I can change the fluid as I have no record of when it was last done.
I changed the gearbox oil this weekend as I had no record of when it was last done, the old fluid looked pretty manky. I haven’t noticed any change in gearbox smoothness or anything with the new oil but at least I now when it was last done now. Like most other things it’s a very easy job, drain the old fluid, squirt new oil into the gearbox filler hole until it starts leaking out and your done.
I also pulled the spark plugs and they look like she’s running pretty good. This was after a week of city commuting and the bike idling for a minute before being shut off.
Sunday afternoon a small group headed over the Kaimais for some Waikato twisties and a stop of at Bikeshed in Okoroire.
Re: Okoroire. Stayed there a couple of nights earlier in the month. A nice and quiet place. Thoroughly enjoyed relaxing there!
So the R100GS is off the road at present as my Alternator failed at the 2023 BMW GS Rally.
I stopped at a gas station in Rotorua on the Friday afternoon and when I hit the starter button all I got was the solenoid clicking. A local battery shop behind the petrol station hooked up a test meter and diagnosed the fault as a failed battery but didn’t have a replacement they could sell me, BNT on the other side of town did however so I shot over there and $380 later I thought all was sorted.
The next day however 40km into the event and 30 meters before the first gravel the GS came to a halt, it would crash start but only run for 20-40 seconds.
Event organiser Vege had a trailer on call so he came out and picked me up and the rest few hours were spent picking up a V-Strom who rider had taken a tumble requiring an ambulance before heading back to camp.
A new alternator and the removal tool is currently making its way to me from Two Cats Garage.
I’ve been a bit slack with this thread.
I replaced the alternator that failed at the 2023 BMW GS Rally thanks to Two Cats Garage and the bike has been running sweet again.
I’m still slowly working through the bike to ensure I know what maintenance level everything is at so I pulled the jets from the carbs last week.
It’s generally recommended to replace the needles and needle jets at 60,000m/100,000km and the bike has done 77,000m/123,000km. Both needles show signs of wear in the idle to ~1/4 throttle opening range.
The bike runs great but I’ve always felt wasn’t quite as ‘responsive’ at low revs as my old R100GS PD. I’d put that down to geographic market differences as my old GS PD was a Euro spec model with 8.5:1 compression and 40mm carbs whereas this bike is a US spec with 8.3:1 compression and 32mm carbs, but maybe this has something to do with it as well.
Thanks again to Two Cats Garage down Wellington way I’ve got replacement needles, needle jets, and a few other bits I felt needed replacing while I’m in there ready to go in.
This week was new tyres week. Both the front and rear tyres had worn down to the ear markers.
The front was replaced with a partially worn Metzler Enduro 3 I already had in the garage and the rear is a new Dunlop K850A, Mileage at the time of change is 72,400 miles.
Over the last week I’ve put in the new needles and needle jets. Someone even more ham-fisted than me had been in there before me and knackered the top of the screw that holds the needle in the slide on one side so I had to replace the whole slide as well.
I’m still to get the carb balance and idle just right but it just feel better, just a little more willing at low revs.
What main jets are people running in their 32mm carbs fitted to R100GS? Mine has the stock 135s but I’ve seen quite a few comments online about 135 being lean for emissions and people running 145 and 150s. @Box.a.Bits?
First ride for just over a month due to being overseas, it was good to be back on the bike. The front tyre was flat when I wheeled it out of the garage but it held air when pumped up so not I’m sure what that’s about.
From Tauranga I headed over the hill to Matamata and stopped to check the tyre pressure and it was unchanged so on I went.
Just up the road from Matamata is a memorial to what was at the time NZ’s worst air accident.
A little further along the Old Te Aroha Road on is Thompsons Track so I headed up to the start to see what sort of condition it was in, and was surprised it was much better than the massive ruts last time I was here. I’m past riding GS’s up stuff like this so didn’t try to go any further.
There’s fantastic views from around here also back over the Waikato.
A little further towards Te Aroha is Wairongomai Valley, I used to tramp up here many years ago, there’s lots of old mine workings as you head up the mountain. It’s definately been discovered though, the carpark was twice the last it used to be and was full of cars.
The last stop was the Te Poi Tavern, my current favorite watering hole while out on the bike, less pretentious than the Okoroire and I find the riders there tend to be more open to a chat.
While there a couple of young un’s came in and parked next to their grand daddy.
Then it was back over the hill again, just under 18okm all up.
I got out for a few hours today and headed over the hill into the Waikato, up to Te Aroha, over to Waitoa were I found a neat little 100 meter track from the rest area on the East side of town, down to Te Poi pub and back over the hill again, about 180km all up.
The bike is running sweet and it was good to be out, though the temperature has definately shifted from summer to Autumn.
I’ve been having issues with the front tyre going flat. 1 day after pumping it up it will be ok, Day 2 maybe down 3-4 psi, Day 3 down 6-10 psi, Day 4 and the tyre is as flat as a flat thing.
The tyre was only fitted 3 months ago and I couldn’t see anything obviously wrong but it is a used tyre I supplied, even though it still has 90% tread.
A bit of googling indicated slow leaks are not uncommon with these rims, but fast ones are not. It turns out a few people have had issues with 30 years of soapy water residue from tyre fitting building up on the inside of the rim bead causing the bead not to seal properly. My bike is 32 years old this year so I pulled the tyre off the rim to have a look and sure enough there’s a significant buildup of gunk all the way round.
This is after one go around with some tar and bug remover I had handy which took off a visible layer of think gunk. I think the next go with be with a brillo pad or similar to smooth things out a bit as the loose stuff is gone but there’s another solid layer to go.
While out of a ride yesterday I stopped to adjust the rear shock and when I tried to get going again all I got was a loud click when hitting the starter button.
I’d done about 250km today with half a dozen stops and up until what was fortunately going to be the last stop before home anyway and the starter had worked flawlessly. I was in a rest area when it failed and a guy had one of those battery jumpstart packs which we tried and that made no difference. He gave me a short push and away the bike went.
Once home I tested the battery, its only 10 months old and when tested at the terminals after the ignition had been on for a minute or 2 with the headlight running it was still 13.02v.
I was hoping it was going to be the starter relay as they are cheap and easy to replace but after some testing it sounds like the magnets in the starter motor have come loose. This is a known problem in the Valeo starters and seems is why they fail 99% of the time..
The starter button issue turned out to be a dead starter motor so a new one was sourced from the US as my usual supplier of BMW airhead bits didn’t have any in stock. That took the better part of a month to come in so it was back to riding the Zero for a bit.
My choke cable splitter/junction box had also died, the internal slider that holds the cables had broken so I ordered a nice aluminium one of those that should outlast me, and a pair of 145 main jets.
I’ve read a few reports of people changing the 135 jets in the 32mm Bings carbs fitted to US R100GS models and getting much better upper revs performance as the US R100GS has the same jetting as the R80GS from the factory. So far I’m not convinced.
I had a good test run on it anyway on roads out the back of Putaruru.
I attended the 2024 BMW GS Rally a few weeks back and one of the other airheads has this cool sidestand extension.
For those that don’t know, on the airhead GS models its virtually impossible to put the sidestand down while seated on the bike without having a hinge in the middle of your shin, or delicately balancing the bike with the sidestand just barely touching the ground and leaning it over with the very real risk of it all going rapidly wrong.
I will keep my eye out for a suitable length of rod with a view to doing this mod in the future.
The Dunlop K850A installed at 72,400 miles has come off the bike as it was done at 75,400 miles. That gave 3000 miles or 5000kms of use and was a good tyre for the $100 I paid for it new. I never had any traction issues with it and it would happily go right over to the edge of the tyre. The R100GS is a hefty beast at 210kg wet so on a lighter bike you might get more life out of it.
The Dunlop K850A’s replacement is a Shinko SR244.
The partially worn Metzler Enduro 3 I installed at the same time as the Dunlop K850A probably has another couple of months left in it.
I got away last weekend down to Pureora Foret for an overnight camp. I chose Piropiro Flat campsite as its one of the few DOC campsites in the area you don’t have to book in advance.
There’s some great roads and country down that way.
I got set up at PiroPiro Flat
I had most of the campground to myself with just a group of hunters at the far end and a family group behind some trees about halfway down. Talking to some people there and that morning the site had been packed out but 95% of the people left during the day.
A few kms up the road is Endeans Mill which I’d been wanting to see for a while.
Endeans Mill is a closed timber mill with numerous old buildings and vehicles scattered across a large area on both sides of the public road. If you are a keen photographer and just want a closer look there are signs nearby to contact the owners who will take you through fore a $20 donation towards upkeep of the site. It is private land so entry is only possible with the owners permission. Everything here was visible from the road.