|06-02-2012, 12:11 PM||#166|
Joined: Mar 2005
Location: San Jose, CA
I spent the long holiday weekend finishing up a lot of the small miscellaneous work. All those small jobs ended up taking a lot of time.
To get a 12mm socket on the final drive mounting nuts I needed to grind some of the weld off the lower swingarm stiffener I added.
The longer swingarm would need more oil, so I looked at the specs for the SWB and LWB /5's. The LWB has a 50mm longer swingarm and takes 25cc more oil, so for my arm I added:
orgs oil = 150cc + 125mm * 25cc / 50mm = 212cc
I swapped out the bean can I had overhauled before for another that needed service. I wanted to find a replacement oil seal. The one in the can was marked 12.5 x 20 x 5. After some searching I found that there is a distributor seal kit (part number 969330K) for 1988-1991 Volvo 780 Turbos that has a 12.5 x 20 x 5 seal in it. I ordered a kit to have on hand, but just lubed up and reassembled this can with the old seal.
I wanted to use some LED turn signals because of their longer 'bulb' life and reduced power, but the GS flasher unit cannot drive the higher impedance LEDs properly. Also, the later model R100GS uses the K-bike controls which use momentary switches to engage the signal and a single momentary switch to cancel. The controller unit is not just a simple thermal flasher relay, but has some more circuitry for the logic needed.
It was a little pricey, but as an easy way to get things to work I bought a Kisan Electronics Signal Minder model SM-6. This unit can drive LED signals, and has some other added features.
I was a little disappointed that it wasn't a direct replacement. I wrapped it in tape to insulate the connectors from grounding against the frame and used a tie wrap to attach it. I'll work on a permanent mount for it if I decide to use it, but I may just convert to a simpler system that doesn't use the GS controls.
I bought some Lockhart Phillips short stalk signals and made these slots in my tail light bracket for them. The wires come out the center of the signal mounting bolt, so with a slot I can remove the signals easier.
For a clean look I routed the harness under the back of the fender. It comes out from a hole near the rear rack, then up to the front of the sub-frame.
I put the front signals on the side of the dash.
I had a trashed R100GS SupperTrapp exhaust that with some encouragement and bailing wire I got to fit with my swingarm and subframe.
Its been a long time since I've had the bike out of the garage, but after checking all the wiring, hooking up the fuel lines, filling the final drive, mounting the battery, etc. I couldn't think of any reason not to bring it out. I used this differential manometer to get the carbs balanced.
I don't have a side stand yet so use this step to prop the bike up.
|06-02-2012, 02:01 PM||#167|
Joined: Feb 2004
Location: Bakersfield CA
2004 BMW 1150 GS-1993 BMW R100GSPD-2009 Yamaha TW200 1961 Sunbeam Alpine
Some people try to turn back their odometers. Not me, I want people to know 'why' I look this way. I've traveled a long way and some of the roads weren't paved. Hell, some of the places I’ve been there weren’t even roads!
|06-03-2012, 10:16 AM||#171|
Joined: Jan 2004
Location: ... I was born a ramblin' man
Nice to see the bike mobile, especially after the great build report ...
The perverse must persevere
|06-03-2012, 12:41 PM||#172|
Joined: Apr 2011
I'm proud of myself after changing my own brake pads. I might even brag to my girlfriend. But this? This is just ridiculous.
'02 BMW F650GS Dakar
'09 Honda CBF1000
'93 Yamaha DT50
'93 Dnepr MT-11
'83 Vespa Primavera ET3
|06-23-2012, 01:41 PM||#173|
Joined: Mar 2005
Location: San Jose, CA
Equal Length Tubes
The exhaust system is one of the things that really makes a bike's character, and I figured I'd like to have one that was distinctive. I'd need something that would work with my repositioned foot pegs and custom sub-frame. The idea of custom stainless sounded cool, but I was a bit unsure if I could make that happen; two tubes snaking around the bike, close to the frame, fitting into the head, no leaks, ground clearance, coming together, welded stainless, what to buy.
The info I found on exhaust system design was mainly for cars. Some of it was useful, but some was clearly incorrect. A good one on welding is here at Burns Stainless.
For my use I want good low and mid-range power so I decided to make some long primary tubes close to the 38 mm outside diameter of the stock GS. I studied the catalog at Columbia River Mandrel Bending and found a selection of 1.5" OD 16 gage 304 stainless bends. 1.5" equals 38.1 mm, and I though I could do something to get that to fit into the 38 mm exhaust port. To get an idea of what would work I made up some paper patterns. This one is based on a 2.25" radius 180 degree bend mated to a 3.0" radius 45 degree.
After a lot of thought and mockups I put in an order for a selection of bends. I ended up not using the big U bends seen. Once I received the bends I thought the 16 gage was a little heavy, but indestructible. Maybe 18 gage would be better.
I used the solid sealing ring as a guide and filed the tube until it fit into the exhaust port.
Here's a stock R100GS exhaust header. I wanted to not make mine any more vulnerable, but saw no reason to match the shape of this one.
I used this setup to make sure the upper end of the 45 degree bend intersected the U bend at a tangent. The larger board in back extends out parallel to the plane of the U bend.
Once I got the lower end of the 45 to follow the frame where I wanted it and the upper end to be in the same plane and touching the U bend I marked where the cuts were needed. I used the geometry of my setup to get the cut point of the 45. The tubes are 1.5" diameter, and at a tangent to the U bend, which has an outside radius of 3" (2.25 + 1.5 / 2 = 3), so I figured to move the 45 bend back along the axis of its lower end until it mated with the U bend I would need to move the cut up by 1.5", the green mark shown.
I used this setup with the 3" side of some 1-2-3 blocks to make a mark the was perpendicular to the bend. The tubes have a 2.25" centerline bend and 1.5" OD, so any centerline radius would be 3" (2.25 + 1.5 / 2 = 3) above an outside tangent.
Here's how I got the inside.
I tried using a hacksaw, but I guess the stainless would work harden and it was really tough going. I ended up using this abrasive cut off tool then finishing with some grinding and filing as needed to get the joint fitted without gaps.
Even though I still had a huge amount ahead of me I was really happy to get this far.
On the right I needed to route around the oil cooler lines. It seems equal length header tubes have desirable performance properties, and I read they are a source of pride for header builders, so I figured I needed them too.
I measured that the right cylinder is 40 mm in front of the left, but in my design I wanted the muffler on the left, so the right tube would need to cross over to the left side in back of the trans. That cross over adds more than the 80 mm gained from cylinder offset, so I made the right tube as short I could while clearing the oil lines. To get the tight route I decided I would arrange it so that to change the filter I could remove the rear muffler section, loosen the exhaust port nut and swing the right header tube out enough to access the filter.
To fit the right side I used the cut part of the left hand U bend and a new 2.25" U bend with one end cut down to a minimum. If the mating ends were in the same plane a straight edge touching both would naturally be at tangents, so it was easy to mark the cuts and measure the length of tube needed to connect the bends.
Stainless steel oxidizes at welding temperatures, so special care should be taken to avoid oxidation of the back side of the weld. The standard methods are to either back purge while welding by sealing the tube ends and filling the tubes with welding gas, or use a stainless welding flux. I used this Type B Solar Flux. I found that a contact lens case makes a nice mixing container. The methyl alcohol that it needs to be mixed with evaporates quickly and this case can be closed up while working.
The flux seems like a vitreous enamel that melts and forms a liquid seal that crystallizes when it cools. Here's the back side after a weld.
To mock up the tubes I used these sleeves made from plastic drink bottles and hose clamps. They didn't make super solid joints, but it made things a lot easier. With the clear plastic I could center the hose clamp over the joint.
I wanted to route the tubes in close to the frame, but there are just a few bends available in the catalog to work with, and that really complicates the process. I spent a lot of time fitting the rear parts, getting a nice route where both tubes would come together in the back where I wanted them to.
I used this piece of larger tube to mark straight tubes for cutting.
I chiseled out a few threads in this hose clamp to help tack weld in tight places.
At first it was hard accept that it was welded together, but it just didn't work. After breaking a dozen joints or so I found I would do it without hesitation just to try a minor adjustment.
I laid the bike over like this while working. I had a stool positioned on each side so I could flip it back and forth as needed.
I used some wide boards against the rear tire to get the tube ends parallel to the bike's centerline and positioned to clear the tire. To check the tube length I laid a piece of string over the centerline of the tubes.
To make it easy to get the left tube out of the cylinder head I wanted to route the left tube such that it would clear the foot peg when swung out.
Once I had the tube routing done and all joints tacked I measured the tube lengths and found I needed to add 28 mm to the left tube. I had planned on needing this adjustment and arranged for the left tube to be positioned such that I could add 14 mm to the tube where it fits into the exhaust port and add another 14 mm to a straight section under the cylinder to make up for the 28 mm difference but leave the rear routing of the tube unchanged. The photo of the melted flux shows the 14 mm end extension.
As received, the tubes have a lot of tooling marks from the bending process. Once I got the tubes tack welded together I spent some time polishing before doing the final welds. Here's the setup I used to do the final welds. With the round profile of the tubes I found I needed to be very careful to keep the torch near perpendicular to the tube to get proper gas coverage to avoid oxidation.
The finished equal length tubes.
To do a final more accurate check I taped up the front ends and filled each tube with water using this graduated cylinder. I was really surprised to find that the difference was within the accuracy of the cylinder, so within about 1 ml. The volume was 1100 ml each, just over two displacements of the engine's 490 cc cylinder.
I used this expander on the right tube to get a good seal at the exhaust port. The short tube end was drawn smaller near the bend.
Here are a few views of the finished tubes installed.
Stainless steel is cool to work with, its really nice to get it polished up.
At the start I didn't know what the outcome would be, and it was a lot of work, much more than I thought, but when I look at the result I am very satisfied with my exhaust so far.
|06-23-2012, 03:05 PM||#175|
Joined: Apr 2010
Location: Orange County, CA
now all you need to do is take them to a tubing place like advanced tube in huntington beach and they can bend that up on a computer inside mandrel bender.
im sure people would love to have a set of pipes like that
|06-23-2012, 03:29 PM||#176|
Joined: Apr 2008
Location: Road Island
|06-24-2012, 03:27 AM||#177|
Joined: Oct 2009
Location: London, United Kingdom
That's a serious amount of work, and fascinating to follow along with the process. This bike really is going to be a complete one-off labour of love.
|06-25-2012, 02:28 PM||#179|
Joined: Oct 2007
Location: Shenandoah Valley
"If you hold a cat by the tail, you learn things you cannot learn any other way."
|Thread Tools||Search this Thread|