ULTIMATE RD: YAMAHA RD400 RESTOMOD

[Bwana]

Needs one of those gold anodised alloy heads with the radial fins you see on all the other RD specials these days.

DG? I've got a Daytona I picked up a few years back with one of them. It's still not running.

[KungFooBob]

Needs one of those gold anodised alloy heads with the radial fins you see on all the other RD specials these days.

DG? I've got a Daytona I picked up a few years back with one of them. It's still not running.

Yup.

[demographic]

So looking at those expansion chambers, I can't see that much mention of them in the blurb but they look like stainless steel to as its more yellowish colour than chromed expansion chambers.
They might even have been tig brazed but I know almost fuckall about that.

I've never seen any stainless expansion chambers before but they do look bloody nice.
Ive just hit search to see who makes stuff like it and it seems Higgspeed in Blackpool makes some for old bikes but they look like the standard pipes.
Tyga on the other hand made them for quite a few bikes, RGVs, Aprilia RS250s, Cagiva Mitos, Honda NSR 250s (various versions) 350 LCs and a few others.
https://www.tygaeurope.com/index.php/by ... s.html?p=1
This one is for a YZ250.


No idea how well they perform but they sure look good.

[Le_Fromage_Grande]

Everyone of those welds is going to put a ridge inside the expansion chamber, a pressed seam welded pipe would work better.

Though it must be cheaper to make them like this because I just had a look at Jim Lomas's web page and his downpipes now have a lot more welds in them than the set I bought in 1990.

[demographic]

Everyone of those welds is going to put a ridge inside the expansion chamber, a pressed seam welded pipe would work better.

Though it must be cheaper to make them like this because I just had a look at Jim Lomas's web page and his downpipes now have a lot more welds in them than the set I bought in 1990.

Dunno, I've done a very limited bit of pipe welding for a company called Press which ended up being used for BNFL yonks ago and done right the internal bead was virtually buggerall, plus you can dress it with a die grinder or even sander as you're not welding the whole thing up in massive sections.
It should be about as neat on the inside as the outside if the welder knows his (or her) stuff.
To have a massive hanging root weld is a fail for the inspection process on thicker wall pipes like I was doing and I can't see if being much different on thin wall.


Some of the other more production pipes are pressed (well, damn nearly all) then welded up and some are hydroformed with all the bends in one plane, then cut and then rotated so the corners conform to the shape of the bike and then welded up in that shape.
A plumbers hydro test pump is sometimes used to pump them to initial shape.

[Mr. Dazzle]

We used to do a fair bit of hydroforming for motorsport exhausts, as you say it's quite common to do a kind of 'cut and shut' where you form some funky sections on a straight pipe than cut it and stick it back together to get the corners.

Some of the stuff was a right mix of traditional bent, hydroformed, 3D printed, machined from solid and fabricated from flat sheet, all in one manifold.

[Taipan]

So looking at those expansion chambers, I can't see that much mention of them in the blurb but they look like stainless steel to as its more yellowish colour than chromed expansion chambers.
They might even have been tig brazed but I know almost fuckall about that.

I've never seen any stainless expansion chambers before but they do look bloody nice.
Ive just hit search to see who makes stuff like it and it seems Higgspeed in Blackpool makes some for old bikes but they look like the standard pipes.
Tyga on the other hand made them for quite a few bikes, RGVs, Aprilia RS250s, Cagiva Mitos, Honda NSR 250s (various versions) 350 LCs and a few others.
https://www.tygaeurope.com/index.php/by ... s.html?p=1
This one is for a YZ250.


No idea how well they perform but they sure look good.

Looks like my Fakerapovic!

[demographic]

Found a vid of a bloke hydroforming various shapes with a pressure washer, I know a lad who made some steel signage lettering in baloon shapes using this technique a few years ago, think I'd mentioned an article I'd seen in Performance Bikes and he took it from there.
Anyway, this makes for quite a good watch IMO.

[Mr. Dazzle]

Not watched the video, but that top left one ain't looking too clever

The expense in hydro forming comes from having a tool of course (a mould you blow into), that's what you need to get the really funky shapes. You need to take care you don't make a tool you get your bit stuck in though, but you won't be surprised to hear there's all sorts of CAD type stuff to help with that.

We messed around with 3D printing tools which seems to work.

[demographic]

Not watched the video, but that top left one ain't looking too clever

The expense in hydro forming comes from having a tool of course (a mould you blow into), that's what you need to get the really funky shapes. You need to take care you don't make a tool you get your bit stuck in though, but you won't be surprised to hear there's all sorts of CAD type stuff to help with that.

We messed around with 3D printing tools which seems to work.

Thing with it is you inflate it and if or when water escapes you drain it, heat it til the waters out and weld that bad seam up and maybe fill it with water, make sure theres no air in then continue inflating it til its hopefully the right shape.
Doing it into a die will be far more repeatable I guess and you wouldn't get me even close to anyone trying to pump it up with air.