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Old 03-27-2010, 04:33 PM   #16
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Joined: Oct 2004
Location: Shawangunks
Oddometer: 26,893

That is pretty amazing. Savage is an excellent word.

Unintentional psychokinesis.
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Old 03-27-2010, 04:47 PM   #17
Dare to be Stupid
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Joined: Jul 2008
Location: Washington, DC, USA
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holy crap man. I've seen plenty of fork swaps but nothing like that.
'85 BMW r80G/S--Another G/S on the road--Central America on a Shoestring--Nova Scotia on a Shoestring--Never Leave a Man's Behind

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Old 04-03-2010, 11:01 AM   #18
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Fitting Tanks

Given the will, there is a savage way!

I've been pushing to get all the frame welding done so I can move on to other things. I added two gussets to the shock mount to give it a better connection to the frame.

A big box arrived by air freight from Germany.

I really liked having the big tank on the PD. I've done 1000 mile days with it where I just needed to fill-up a few times. A big tank is really nice when you go off into the mountains for a day or two and don't need to carry extra cans. I'll have this big tank for trips, and use the R65 tank for local riding.

I got the more expensive nylon tank that can be painted. I figured it would be a better investment, as I can repaint it when it gets scratched-up or when I want to change the color scheme.

I made up this pattern in the lower right for the front tank mount bracket.

I don't have a photo of the unmounted bracket. I fabricated it out of 1/8" flat stock and drilled a big hole in it.

I used a piece of welding rod and a bubble level to align the two brackets on the frame, then tacked the brackets.

The welded brackets look a little flimsy. I'll add another support running from the inside of the down tube to the bracket, but I don't have any stock of that size. I'm thinking 1/8 x 1/2 will work good. Here's how it looks with the tank.

For the rear mount I made up these bungs with a M8 x 1.25 threaded hole.

I bolted the bungs up to the tank to get the alignment for welding.

As seen in the photo, the tank mounting tangs are not quite even. I thought the reason for the difference was that the two gussets were not aligned, but after welding I checked it and it was the tank. I should have done the check before welding it up. I can fix the tank by shaving some material off the the one side, or gluing a spacer on the other. I can fix the frame by either welding a washer on the low side, or grinding the high side.

I used some thin sheet aluminum to make a heat shield between the bung and the nylon tank, but the tank got hot enough for the nylon to melt a little when I did the tack weld. After welding up the bung I chased the threads with a tap.

As I mentioned in an earlier post, I got this black R65 tank off ebay. I really like the shape.

I like the lines of the tank and this GS long seat.

The R65 tank is longer than the HPN tank so I made up this adapter plate. Whenever I want to use the R65 tank I'll need to bolt on this adapter.

The R65 uses a hanging swing type of mount in the rear, but there was just no way to get that working with this modified GS frame, so I took the old mounting hardware off the tank and made up a new mounting plate from 1/16" flat stock that will bolt to the frame adapter plate. Here I have the new mounting plate clamped to the tank and ready for tack welding.

Once, when I was a kid, I was working on the tank of my Hodaka Super Rat and the fumes in the tank ignited. It was a minor explosion, but scared the hell out of me. Since then every time I work on a gas tank with heat I do this check.

Here's the plate tacked to the back of the tank.

Here is the modified tank bolted to the adapter plate. I just have some spacers that were handy in there to check the fit. I'm thinking to make another smaller set of M6 bungs to weld to the adapter plate.

The fitted R65 tank.


x3300 screwed with this post 07-29-2010 at 06:46 PM Reason: Fix broken URL.
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Old 04-03-2010, 06:52 PM   #19
Gnarly Adventurer
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Joined: Jan 2006
Location: Los Angeles
Oddometer: 282
Damn fine work! and good tank check
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Old 04-03-2010, 07:33 PM   #20
Plated and screwed
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Joined: Sep 2008
Location: Lenoir City TN.
Oddometer: 1,522
On the subject of welding gas tanks, a guy i know welds on motorcycle gas tanks quite often, one day while he was doing one i ask him how did he get them clean and free of fumes, he said he did not worry about it, he just emptied the tank and ran a Argonne gas line into the tank while welding and that would prevent any fumes from igniting.
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Old 04-03-2010, 08:44 PM   #21
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Joined: Oct 2004
Location: Shawangunks
Oddometer: 26,893
120 ppm @ 120degF i think is the flash point of 87 octane gasoline.

Thats all that matters.
Unintentional psychokinesis.
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Old 04-03-2010, 09:03 PM   #22
Beemerguru...G/S guy
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Joined: Nov 2006
Location: Foster City, CA
Oddometer: 998
Great job and wonderful when the frame is ARE going to send it off to the Frame Man to straighten it out aren't you?
Greg Hutchinson
BMW Club of Northern California, Ambassador, BMW MOA, Vice President Vintage BMW Club
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Old 04-11-2010, 09:57 AM   #23
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Tank Mounts

Beemerguru, I aligned the steering head when welding it on, and it looked OK after I was done, so shouldn't need any further alignment.

If some frame alignment was needed, well, this project is not about sending things out. It is about creation, about taking an idea, forming a concept, and realizing it in metal, rubber and plastic. A sturdy fixture to bend the frame into alignment would just be one of the many fixtues and jigs that will be made for this project.

I found some thin sheet stock and cut two shims from it to set the steering stop to just before where the steering damper hits its limit.

The Applied Racing triple clamp I bought mounts the damper in the reverse direction, so I needed to buy a stepped arm that drops down to clear the damper body. I made this puller to pull the old arm off.

As I mentioned in my last post, the front HPN tank mounts I made up seemed too flimsy, so I added a brace to the inside of the existing bracket. I found some rusty stock that I cut to fit.

Then welded it on. It is amazing how the triangle makes it really strong, I guess the whole bike could be picked up by just one mount.

To fix the botched rear HPN tank mount I cut the welds of the miss placed bung with an abrasive cut-off wheel, ground off all the old weld, then re-welded the bung at the correct hight.

I made up this set of smaller bungs with M6x1.0 threads for the R65 tank adapter.

I needed to set the bungs up so that the bottom of the tank will clear the heads of the bolts that mount the adapter to the frame.

After I figure out what I'll do with the front seat mount, etc., I might simplify things here by cutting up this adapter such that I can just weld it to the frame.


x3300 screwed with this post 05-09-2010 at 08:28 AM Reason: Update URLs.
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Old 04-13-2010, 07:48 PM   #24
Joined: Apr 2010
Location: NorCal
Oddometer: 44
Something wicked this way comes!
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Old 04-13-2010, 08:59 PM   #25
What could go wrong?
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Joined: Mar 2007
Location: Beautiful Revelstoke BC
Oddometer: 5,664

Cool build
I'm in
Kawasaki H1 build thread

71- 450 Honda CL re & re

Just another pathetic sheep following the herd

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Old 04-24-2010, 02:58 PM   #26
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Front Wheel

I've been busy on a lot of different things since my last post, and could finally get something together worth reporting. Just to let you know where I am going here is a cardboard box 'studio' photo of the result.

These are adapters I found I needed to get all the front wheel related parts I wanted to use mounted up to work together.

Here is a list of the parts:

fork		Honda CRF250R
wheel		BMW R100GS
axle		Honda CRF250R
brake disk	Ducati snowflake (320mm)
brake caliper	BMW R1200RT (4 piston)
I really like the convenience of the stock GS tubeless wheel. It seems really strong, and I can repair a puncture without removing the wheel from the bike. Plus, I just need to carry a small tire plug set and an MTB bicycle pump to do repairs.

The GS axle is bigger than the CRF's. Here is what I measured:

		R100GS 			CRF250R		difference 
axle diameter	25.0 mm			20.0 mm		-5.0 mm
I didn't want to bore out the CRF fork ends to accept the GS axle since that would need to be done again if the fork ever needed to be replaced. I looked into fitting a bearing that would have the OD of the GS wheel and the ID of the CRF axle. The GS uses a number 6005 bearing with dimensions 25x47x12. The closest standard bearing with the proper ID and OD is a 6204, with dimensions 20x47x14. The GS wheel bearing bore is really just deep enough for the 12mm bearing, and I didn't think it the good to use the thicker 14mm 6204.

I did find that some Suzuki motorcycles use a 20x47x12 bearing in the transmission, but those wouldn't be sealed, so wouldn't be appropriate for wheel bearings.

I would need to make some custom axle spacers to fit the GS wheel between the CRF fork, so in the end, the solution I came up with to fit the bearings was to make a set of stepped spacers that extend into the wheel bearing to adapt the GS wheel bearing to the CRF axle.

I found some kind of stainless round stock at the scrap yard that I though I could use. I made the OD of the new spacers the same as that of the stock GS spacers so I could use the GS bearing protectors on the new spacers. This shows the stock GS axle and spacers on the right, and the CRF axle and custom spacers with the GS bearing protectors switched over on the left.

To get the correct width for each of the new spacers I mounted the GS wheel in the fork with the CRF axle nut screwed on the axle until the outside of the nut was flush with the end of the axle, then positioned the wheel so that the rim was centered between the fork legs. Careful measurement gave me 15.5mm on the right, and 27.0mm on the left for the spacers.

This shows the CRF axle with my new spacers and GS wheel bearings.

I had done a 320mm disk conversion on my PD earlier, so had a good idea of what I needed to get the disk mounted. You can read my write-up of the PD conversion here:

The Ducati snowflake disk has an offset of 9.67mm, but an additional spacer is needed to get the disk far enough over so that the spokes won't hit the inside of the caliper. Also, it seems to me that if the disk is closer to the fork leg there will be less stress in the caliper mount.

I took the springs out of the fork so I could compress it down the check how thick a spacer I needed to get 2mm clearance between the widest part of the fork upper and the outer surface of the brake disk buttons. I measured that about 11mm would work.

I was lucky and found a 1/2"x4"x4" aluminum cutoff at the scrap yard. I didn't have any proper lathe mandrels so I drilled a hole in the stock and pressed in a piece of scrap steel that I turned down and center drilled. That big square spinning around was a little intimidating at first, but I showed it who as in charge, and quickly got it turned down to its 100mm OD.

These photos show how the axle spacers and disk spacer work together to position the wheel centered in the fork, and the disk as far to the left as possible.

To get the brake caliper setup I just positioned the caliper on the disk to where it looked good. It seems a little high in this photo, I thought it would put too much stress on the upper mount.

The geometry of the adapter needed is not simple. I took some measurements, but mainly made the finished piece from a template.

At first I was trying to make templates from thick card stock, but that turned out to be difficult because of the irregularly shaped parts. I hit on this idea to use a thin piece of clear PETE plastic and a sharpie marker.

Once I got the template and knew the size of the adapter I scrounged around at the scrap yard and found a block of aluminum I could use.

The adapter needed two reliefs on the outside for the fork mounts, and one big one on the inside for the caliper. I just sketched the reliefs onto the template to give about 2mm clearance between the adapter and other parts, then just transfered the sketchings to the piece when doing the layout.

This shows the caliper and inside relief, along with some of my fabrication notes.

I plan at some time to make a proper mechanical drawing of the adapter for use by anyone interested.

The three big holes on the side are to reduce weight and give a better appearance. I didn't plan on those at first, but once I got it machined and mounted up it looked like a big bulky hunk of metal sitting there so I added the holes. I think it looks a lot better, and is significantly lighter. The holes are not quite lined up because I positioned them in the center of the thickest parts to give maximum strength.

This adapter ties together a Honda fork, a Ducati disk, and a BMW caliper...

Here is a top view. The 2mm relief gap between the adapter and caliper is in the shadows of this photo, but looks narrow and gives a really good effect.

It was a lot of work to design and machine the parts, but I am very happy with the result. The axle spacers are stainless, which won't rust, and the caliper adapter has a really cool 'one-off' look to it.


x3300 screwed with this post 05-09-2010 at 08:29 AM Reason: Update URLs.
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Old 04-25-2010, 02:47 AM   #27
Studly Adventurer
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Joined: Jan 2004
Location: ... I was born a ramblin' man
Oddometer: 833
Nice work

The perverse must persevere
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Old 04-25-2010, 03:12 AM   #28
90S on the bench
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Joined: Aug 2005
Location: Tasmania, Australia
Oddometer: 436
Wow, Fantastiic work.
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Old 04-27-2010, 08:24 PM   #29
Mr. Vintage
Family Dude
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Joined: Jan 2007
Location: The Palouse
Oddometer: 867
Nice job!
- Jeff (Mr. Vintage) -
Quota, SL350, MW250, MT250, CT90
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Old 04-27-2010, 08:33 PM   #30
Solo Lobo
airhead or nothing
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Joined: Mar 2004
Location: Shoreline, WA
Oddometer: 9,000
Really nice stuff going on here
"punk rocks what it's all about" - J. Strummer

Originally Posted by Stagehand
your bike is suitably dirty. Well done.
So I sold my GS and went shopping for a G/S!
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