1974 XS/TX650 rebuild

[th62]

I managed to drop the seat, so had to strip and straighten it, the calipers crinkled in a couple of spots, must had dropped some brake fluid on them, so I also stripped and repainted them. 2k paint, so I'll wait a couple of weeks before taking it in to get covered.

[th62]

Catch can build.

I was going to plumb the read valve engine breather into the pancake filters, but didn't like the idea of breathing sump gasses into the inlet, so, I made this catch can.

Not quite finished yet, I rushed it toward the end to see what it'd look like, happy with the result, So I'll probably build a neater one, with a few changes of course.

Matches the pancake filters, but almost unnoticeable

[th62]

So, I finally settled on a catch can design and built it. The first one was simply too big, creating mounting problems, so that was binned. The final one is made of 42mm tube with four baffles. Instead of welding the baffles inside of the tube, I fixed them together with a 4mm screwed and peened the end so it wouldn’t come apart, the baffle cartridge was then pressed into place resting on top of the intake tube so it won’t float around. The intake tube stretches across the diameter of the 42mm tube and has three exit holes underneath. For the blowby gas to escape it has to exit via the four baffles and finally through some stainless mesh before exiting through the air filter on top, set between the two carb filters.

I’ve gone with a remote empty point via a tap connected to the catch can by a rubber hose. The filtering medium inside the can is replaceable via the top plate secured on top by four 4mm stainless allens. The can is mounted to an aluminium bracket by two rubber gromets and two threaded T nuts to stop the gromet from being squished too far, then fixed to the right, rear engine bracket.

Mounting the can proved a little troublesome: behind the motor over top of the swing arm pivot is the only place I could find to mount it. To make it less noticeable I painted it black and welded an outlet on the side so I could mount the final filter between the two carb filters. It is only a small catch can with around 220ml capacity, that’s in total of course, realistically only around 100mm under the baffles. If it proves too small, I can fit a larger container under the swingarm connected to the catch can outlet by a rubber hose.

It’s very busy in this are area now, two carbs, three filters, catch can, fuel distributor block, making it a little difficult to remove the air filter caps.

[th62]

Here it is, another fuel distributor block - number four. Just couldn't help myself.

I moved the inlet spigots closer together, milled a step at the front, round off the edge either side and mounted the block in the battery clamp holes, so it sits further back than it used to, thus giving more room to get at the air filters.

But, the old mounting holes are now visible, I'll address that later on.

Fuel filters are easy to get at, and a bit more obvious than I'd like, but, they are the only 90 degree filters I could find.

No more fuel distributoer blocks though, everywhere I look in my workshop, there seems to be an unused one sitting around looking for a home.

Happy with results now: Looks good, I can get to everything reasonably easy and I have somewhere for the engine blowby gasses to go, and I'm not feeding blowby particulates into the intakes.

[th62]

A little neatening up under the tank.
I had the cable splitter between the top engine mounts, difficult to get at and it was a little busy in there with two wiring looms, throttle cable splitter and clutch cable. So, I made a small bracket to hold the splitter on the outside of the left engine mount. It is now held securely in place, instead of just flopping around.
While I was at it, I attached the clutch cable to the right side, top engine mount via two small P clamps.
The cables that came with the VM34s had a curved stell tube which locates inside the top adjuster. This puts the cable in the way of the petcocks when removing/replacing the tank. To remedy, I made two new cables, minus the curved tubes and routed them,over the backbone of the frame.
The cables clear the petcocks now and have just a slight curve to the carbs.

[tonyfoale]

You could junk the splitter completely if you used the 1970s TZ yamaha dual throttle control. The throttle action is smoother than you get with a splitter. Genuine ones will be hard to find at a reasonable price but new "clones" are available, but you easily have the skills to make one. If you become interested in making one I can take detailed internal photos.

Click for full size
Original TZ Yamaha


Modern clone.

[th62]

The 74 TX650 came with a dual cable throttle, nothing but a PITA, so I 'junked' it using a splitter I made for the BS38s. Post 149 here:

1974 XS/TX650 rebuild

This system was far, far superier to the dual throttle, easy to sync, neat and tidy and only one cable to worry about

[th62]

Chain guard build. I’ve been working on this for a couple of days, made a couple I didn’t like, but this is the final product. The bends were done with a bloody big hammer and a length of heavy steel on which to bang – keeps the material straight and flat! Bloody difficult to bend by hand though.
Unsure of what to do with the tail end, I did consider curving it around same shape as the sprocket, but with a new chain, it’d stick out the rear a few inches looking a bit odd, didn’t like that idea, so I decided to just angle it up from the rear mounting point
I might drill some lightning holes on the side, should make the bike go faster.
I’ve also entertained the idea of removing the angled up extension on the left side cover, that bit looks really odd.
On another note, I picked up my seat from the auto trimmers. He’s had it for five weeks and not touched it. Took it to another auto trimmer who quoted $600. Not bloody likely, I’ll visit a few other trimmers tomorrow, at this point though, it’s looking like I might have to cover the seat myself.
Haven’t heard from the tyre shop, if they haven’t got back to me by end of next week I’ll go elsewhere. I’m fitting Shinko 712s, which I’ve read good reports on.
Not having much luck lately.

[th62]

I've just built this centrestand for the shop. No chance of this one breaking. Made of 22mm tube with 2.5mm walls, it's a heavy little sucker. I've made it so it bolts where the original stand was mounted and best of all, even my feeble old body can get the bike up on it by just lightly stepping on the side lever.
The lever is on the right, so if I lose control and the bike topples over, the side stand will stop it. Damn these XS650s are heavy

I've got the tyres on, the seat should be finished this week sometime, then I just have to wait for a speedo to turn up so I can mount that. I've bought a magnetic sensor speedo so I don't have a great heavy cable running down beside the fork. Not the best looking speedo, but all I could find without having to see the bank manager first.

Last pic is of the original centre stand.

[Frank S]

I have watched this thread with interest from the very beginning. A pity that you say you will never be able to ride it. I can see it has been a labor of love and a love of labor, put into this most excellent build.