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Discussion Starter · #62 ·
The amount of hours that go into a full build such as this are adding up. That said so far it's a fun project. One of the aims is for the completed bike to still maintain a period 70's/80's look to the casual observer. Colour scheme will play a part here to divert attention away from the modern wheels and suspension. Typical headlight is of course a must too!

Simple bracket - ultimately epoxied into place with two very short screws tapped 5mm into the lower tree.

Auto part Pipe Suspension Vehicle Metal


Entire lower tree filed smooth and bracket blended in. I also ended up with two different height mounting positions for the headlight to get the lines right.

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I also wanted a steering damper, and managed to tap one of the original bosses under the tree and weld a bracket to the frame to tuck it in nicely with the correct ratio. Again this is factory GSXR.

Auto part Tire Pipe Vehicle Suspension part


And lastly smoothing the top triple tree after removing the factory ignition key and mount. This is a bit fiddly as I need to keep the detail in the shape on the leading edge. The top tree is very visible so I want this part correct. Idiot lights will go into the recess on the right.

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Cheers,

Earlysport
 

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Discussion Starter · #63 ·
More detail / refurb stuff and a little more fabrication this week.

First up an internal medium wall reinforcing tube fitted into the lower shock pivot tube ( originally centre stand tube and frame cross tube ). A bit of thin fibreglass and resin used to fill any voids as the pipe was knocked into place. The factory tube is thick wall so this is really just for security.

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I intend to run minimal instrumentation and will probably use an iphone or small bicycle speedo, but I wanted a decent tach. Not many two cylinder electronic tachs out there that have a scale to 10K rpm. This glowshift was the best option for me, as I needed a small size. This mount is made from some PVC tube epoxied into place and then filled. The tach is a perfect fit just in front of the tank and under the top triple.

Auto part Suspension Suspension part Engine Pipe


Also started cleaning up the engine ready for paint, and decided I don't need yamaha logos on it. Some metal filler followed by a skim coat of bondo took care of them.

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And lastly I recieved my carb rebuild kits so have now gone through the carbs and cleaned them up, and hit them with some high temp paint and re-assembled. Color on diaphragm tops will probably change - I have a color scheme in mind now.

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Cheers

Earlysport
 

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Bondo on triple clamp? Bondo on frame? Tubes bashed through and secured with resin?

I'm glad I've never been near any car you've built.

I've seen crashed old Porsches owned by gentlemen in your league. Bits of GRP wrapped around trees, and the motor/trans hiding in the bushes.

" Hey, you're a CAR guy, right? "

Tripebuns, is awaiting your email, with barely contained eagerness.
 

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I would consider a different front bracket for that headlight. The bond from the bracket onto the lower yoke would make me nervous as it could part company when in service. You could consider welding a tube from your headstock to mount the lamp onto and then also engineer something to line up with those alloy tabs for a steering lock while your at it.

Not sure about bonding plastic pipe with filler on the frame or your reinforcement tube. If you are worried about the existing section not being up to the job, it would be better to remove that tube and replace it with a heavier gauge piece, rather than lining the existing with a sleeve and resin.
 

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I would consider a different front bracket for that headlight. The bond from the bracket onto the lower yoke would make me nervous as it could part company when in service. You could consider welding a tube from your headstock to mount the lamp onto and then also engineer something to line up with those alloy tabs for a steering lock while your at it.

Not sure about bonding plastic pipe with filler on the frame or your reinforcement tube. If you are worried about the existing section not being up to the job, it would be better to remove that tube and replace it with a heavier gauge piece, rather than lining the existing with a sleeve and resin.
The headlight bracket really needs 8.0mm bolts, 5.0mm ones are a bit on the weak side.
 

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Fibreglass filled steel frame tubing and a bondo reinforced steering head :|
That's some pretty interesting composite technology being explored there … would fibreglass filled tubing be about 20% as strong as a solid steel bar and half the weight, or would it be 10% stronger then a hollow tube and twice the weight ? … and are we going for torsional strength here, or strengthening the welds and making the tubes harder to bend ?:I


:I have a trials bike speedometer you could have for free, but the shipping charges to Australia would probably make it very expensive. I think it registers up to 120kph, how fast do you think you need it to go ?
 

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Exactly.

That motor does not have fragile engine/head cases, it was designed from the start for extreme stressed member service.

FreE wIne : hic.
Take a close look at the mounting point in the top rear of this engine, and the lack of material around it, do you still think that engine casing was designed for "extreme stressed member service" ?

 

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Take a close look at the mounting point in the top rear of this engine, and the lack of material around it, do you still think that engine casing was designed for "extreme stressed member service" ?
Absolutely. That 2nd gen XS250/400 motor, was designed from the very start to be held by the back of the motor, and by the head studs and therefore to the head steady to the frame. They were never fitted to any full loop frames, as far as I know.

Like FZ750s , big Viragos and even XT/SR250s, they were never fitted to "full frame loop" bikes. They all had stressed member engine cases from the very start, with a pencil from the designers head.

Danger, is my business.
 

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Absolutely. That 2nd gen XS250/400 motor, was designed from the very start to be held by the back of the motor, and by the head studs and therefore to the head steady to the frame. They were never fitted to any full loop frames, as far as I know.

Like FZ750s , big Viragos and even XT/SR250s, they were never fitted to "full frame loop" bikes. They all had stressed member engine cases from the very start, with a pencil from the designers head.

Danger, is my business.

Look again, there is barely enough meat there to hang that motor from.
 

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Look again, there is barely enough meat there to hang that motor from.
A CBX1000 has about three times the power, and the motor weighs about 110kg. It is mounted on a very similar casting, at the rear on two bolts, to the XS400. I'd guess the XS400 motor weights about half the CBX.

I've never heard of a CBX, XS400 or any other stressed member motored bike ever having the rear mounts break. I've heard of Ducatis breaking the frame on stressed member motor bikes, but that figures with the cheap Italian junk.

Danger, is my business.
 

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Discussion Starter · #72 · (Edited)
Bondo on triple clamp? Bondo on frame? Tubes bashed through and secured with resin?

I'm glad I've never been near any car you've built.

I've seen crashed old Porsches owned by gentlemen in your league. Bits of GRP wrapped around trees, and the motor/trans hiding in the bushes.

" Hey, you're a CAR guy, right? "

Tripebuns, is awaiting your email, with barely contained eagerness.
I kinda gather you don't like cars Witworth? That's ok - each to his own. I've done a reasonable amount of Porsche club racing, but the tracks we race on don't have trees or bushes, but I'd imagine it is possible to crash a porsche bad enough to tear the car in two. I've also used plenty of fibreglass body parts on Porsches too - one of mine is 940 kgs ( about 2040 lbs ) because the front and rear lids, bumpers, and guards are all glass. Of course none of that is structural, and I've never heard of anyone bullding a fibreglass tub ( the structure in a 911 ) but maybe that's what was done in the one you saw crashed?

And yeah, I use bondo. Almost 3mm thick too right next to my headlight bracket. That triple is real visible so I thought I'd spend 30 minutes file finishing it after cutting off the unwanted brackets and then smooth in the headlight bracket so it looks good to me. I could have made an aluminium bracket and tig welded it on and then file finished the lot, but I didn't want to spend 2 hours making it look good, and it'd probably need a skim of bondo anyway before paint.

And hey if Bondo's good enough for Chip Foose it's good enough for me! :)

You may not like it either but I'm actually going to paint this thing, and use some bondo on the tank and rear cowl and waste all this time laying down paint and making it look pretty. I'm even going to paint the engine and frame and wheels. Making it look good will make me happy too :)

On a serious note to the other poster, I did consider cutting out the lower tube and replacing it, but the tube has a bend in it and is pretty thick wall. I cut it apart and widened it prior with an insert. It's also not dead round. The tube I fitted inside it is a neat fit overall but still left some voids, hence the resin and glass. Do I need it? I don't think so, but it makes me feel a little safer knowing it's there inside the 30 year old factory tube.

Cheers,

Earlysport
 

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Yep, I'm a bit anti-car.

(he says trying to keeps a straight face). I was thinking of getting BRZ last month and going full silly, with all the factory bits, 18" wheels and a big stupid carbon wing. I couldn't work out how to build a safe bolt-in roll cage for it and I thought I'd get bored with the power, and have to fit a supercharger. I've been in the drivers seat of one, they are pretty sweet, to drive.

I was thinking of getting new WRX or EVO, but the EVOs look like cheap scary junk, and the new model WRX has pov-pack brakes and same old dorky styling.

I saw an idiot racing around in a crusty red 911 one day, and the next day there was a big chunk out of a tree and bits of glas and stuff everywhere. I found out the ding-dong lived, but the car grenaded
and ended in three pieces.

Danger, is my business.
 

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A CBX1000 has about three times the power, and the motor weighs about 110kg. It is mounted on a very similar casting, at the rear on two bolts, to the XS400. I'd guess the XS400 motor weights about half the CBX.

I've never heard of a CBX, XS400 or any other stressed member motored bike ever having the rear mounts break. I've heard of Ducatis breaking the frame on stressed member motor bikes, but that figures with the cheap Italian junk.

Danger, is my business.



… there that looks better now :|
 

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Here is a motorcycle engine that has been designed as a stressed frame member:


The bikes you think qualify are not even close, they have engine mounts designed to hang the engine in a frame.

If need be, I can explain to you why you would not want to use an aluminum cylinder head and your standard compliment of head bolts to hold a motorcycle together.
 

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Here is a motorcycle engine that has been designed as a stressed frame member:


The bikes you think qualify are not even close, they have engine mounts designed to hang the engine in a frame.

If need be, I can explain to you why you would not want to use an aluminum cylinder head and your standard compliment of head bolts to hold a motorcycle together.
Here is a motorcycle engine that has been designed as a stressed frame member:


The bikes you think qualify are not even close, they have engine mounts designed to hang the engine in a frame.

If need be, I can explain to you why you would not want to use an aluminum cylinder head and your standard compliment of head bolts to hold a motorcycle together.
I guess Irmajiri San was wrong. "Suspended from the frame and acting as a stressed member, the 1,047cc, inline-six on the Honda CBX was a double-overhead cam unit with four valves per cylinder."

Hailwood's GP bike had exactly the same concept, that worked O.K. The RC motorcycle sure looks like it has a stressed member frame from the start. You could hang a helicopter from 18 cylinder studs on that pair of motors.

They are "your standard compliment of head bolts to hold a motorcycle together" , as they are standard, and were chosen to bear the stresses of the application from the drawing board. The next thing you're going to say, is a Vincent hasn't got a stressed member frame that is all held together by it's cylinder studs.

Danger, is my business.

Land vehicle Vehicle Motor vehicle Motorcycle Car
 

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Irmajiri San:/
... what's with all the name dropping and motorcycle spectator history references ?
It's not like you were there or shared a beer with any of these people, so fuck all the nonsense.


stick with bicycles.
 

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Irmajiri San:/
... what's with all the name dropping and motorcycle spectator history references ?
It's not like you were there or shared a beer with any of these people, so fuck all the nonsense.


stick with bicycles.
I'll admit I've not met Irmajiri. Known plenty of other movers though. I don't drop the names I've associated with, sorry.

Danger, is my business.
 

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movers … "I'll admit I've not met Irmajiri. Known plenty of other movers though"
What does that even fucking mean, movers ?
… sounds a little like something a groupie who hangs out at race tracks in bicycle spandex hoping to service somebody famous might say, stop doing that, it oogs me out.

Anyone who thinks a motorcycle engine was designed to be a stressed frame member, simply because it is not sitting in the middle of a hoop frame, is clueless about this shit.


 
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