1974 XS/TX650 rebuild

[IntheGroove]

Lookin good. Keep going...

[th62]

Well, I finally got around to finishing off the right side filter, and damn it looks good. It gives a nice unobstructed air flows, much better than pods. My plan on heating and cooling didn't work too well, much to hard to handle all the bits and pieces and tooling trying to press them together, so, I ended up pressing together cold.

Same with the sizing, .020mm press fit was much too much, so after a few tries I got a good fit by decreasing it to about .04mm. And of course my day wouldn't be complete without misplacing parts, I lost the idle mixture screw spring, no idea where I'm going to get one of them from.

All I have to do now is make an identical one for the left carb from that great slab of aluminium I spent yesterday tracking down, and beat up a rear plate. But first I'll make another fuel distributor block to keep the hosing neat and simple.

If I can remember, I'll take lots of pics of the machining and fabrication process and bore you all to tears with them.

[tonyfoale]

Nice work.

[olderdan]

Nice job, looks much better.

[th62]

I did warn you: Here's loads of pictures taken while making a new fuel distributor block. It's little smaller than the first one I made and routes the hoses from petcock to carb nice and neatly, it also levels the fuel on both sides of the tank so one carb doesn't run dry when the fuel level gets low.

The block is drilled through left to right 5.5mm and has barbs machined on the end to take the 8mm hose going to the carbs. Two 6mm brass barbs are pressed in place on the front which take the hoses from the petcock via a couple of inline filters.

[th62]

Here’s the process used making the air filters. I took sizes of the first filter I made and replicated them to the second. This time I took lots of pictures to outline the steps in making them. I cut a 15mm slice off the 101.6mm lump of ally and turned down one end to 97.4mm, then cut a piece of 1.7mm sheet to around 111-mm in diameter, stuck them together and bashed the overhang until there wasn’t one. I have to use my left hand now, as the right elbow complains. Sound easy, but it’s not, out of every 10 strikes, I think I miss about nine.
Once formed, I mounted it in the four jaw, and turned the overhang down to 3mm, then smoothed out all the scratches and what not with sand paper, finishing off with the random orbital sander with 240 grit.
Next, I mounted the 15mm slab in the three jaw using the turned down area and drilled through with a 25mm bit, machined the outer diameter to 101.4mm, machined out the centre leaving a 2mm wide lip on the periphery, 3mm deep, then bored out the 25mm centre hole to 57.3mm to fit the 57.4 mm carb bell mouth. .10 mm proved a little tight, .07 would have been better I think.
I flipped the slab over and mounted it in the four jaw, then spent a couple of hours trying to centre the damn thing, then turned down the inner mounting ring so its 8mm wide and the flat body of the filter 2mm thick. Final step, turn down the inner mounting ring so its 9.8mm deep.
The cutting tool was then centred., spot on, and used to scribe a line across the back of the centre mounting ring. After removing from the chuck I found the centre point using a calliper, centre popped it, mounted it on the mill and drilled the centre pops with a 4mm bit, then mounted it on the pedestal drill, centred the holes and tapped the 4mm holes with a 5mm x .8 tap. The plate was then turned on its side, and drilled and tapped in the centre of the centre ring at 90degrees to the other two holes on the face.
The piece was mounted in the three jaw again and using 240 grit any cutting ridges were smoothed over, then both plates were polished.
The knurled securing nuts were turned up from a piece of 20mm stock, tapped 5mm and then knurled using the scissor knurler. These were mostly done by eye, so won’t be absolutely identical. You’d need a calliper to pick up the difference though, so good are my four eyes.
The carb body was mounted in the three jaw and a file used to remove the ridge at the beginning of the bell mouth. The face of the bell mouth was pretty rough, so I took the time to smooth that with some emery. The turned piece was located over the bell mouth, the assembly was then stuck in the vice and pressed into place.
The lead into the bell mouth is flat, so not a perfect shape for induction. You can recess the filter lower on the bell mouth, creating a bit of a lip on the outer periphery of the bell mouth to improve induction, but realistically the improvement in induction wouldn’t be worth the time.
Both filters fit well and the hoses from the fuel distributor block lead over the filters nice and neatly. Happy with the outcome, except the inner knurled nuts are a little difficult to get to, probably due more to the fact my fingers are fused, but I can turn them with a little bit of messing around, better still, use the wife, her fingers aren’t fused. I’ve yet to get some perforated sheet metal to replace the stainless crap I used to keep the foam in place.

[th62]

Slaved away today - making a clutch slave cylinder. I made it so it sits in the left cover, protruding through the clutch screw actuatorr hole. I managed to get the tolerances better than the caliper tolerances: The bore is dead on 25mm, the piston dead on 24.97, a really nice fit.

I couldn't find any seals similar to the caliper seals, but found a hydraulic pressure seal and dust seal, but I have to find a 25 mm internal circlip before cutting the circlip groove. I also,have to drill a couple of holes in the collar to suit the holes in the side cover, then bore out the hole in the cover to 30mm and drill out the M5 securing threads. Once done two M5 Allen's will bolt through the outside of the cover, holding the slave cylinder in place.

I did make one mistake, got carried away on the lathe and cut the collar down to 18mm, that only leaves a 6 mm threaded hole in the collar of the slave cylinder. Hopefully this may work as the screws are really on locating pegs.

Before modifying the side cover I'll order a hydraulic hose. Not sure what size master cylinder to get, but I'll try the slave out on the 17mm braker master cylinder first, that should give a clue, unless of course, someone here knows what size master to go with the 25mm slave for a nice light clutch pull: Fused fingers so grip isn't the best.

I'm hoping to find a pair of matching radial clutch/brake master cylinders.

[tonyfoale]

I have seen matched pairs of clutch/brake master cylinders advertised on Aliexpress if you do not mind getting stuff from there.

I think that you will need to get the smallest master cylinder piston that you can find. 25 mm slave is not very large so you need a small master to get a light feel, but if you go too light then you will not have enough movement to free the clutch. Fortunately, swapping those horrible Yamaha scroll release mechanisms for hydraulics means that you have much less lost motion, and so it becomes easier to combine a light feel with sufficient movement.
To put some numbers to it. 12 mm is a common master cyl. size. That is near 1/2 of your slave so the force and distance ratios will be near 4. The release force will be 4 times that on the master piston. I do not know if 10 mm masters are available but that would increase the ratios to 6.25. Of course the hand lever ratio will reduce the hand force further.
I once sleeved a master cylinder to get a smaller piston, I found seals from a GoKart brake.

[th62]

Nothing against Chinese here, they make some exceptional stuff, my stator and rotor are made in China. Most of the stuff you buy in your local, thinking its locally made, is made in China, it just has the locals sticker on it. People are so easilly fooled, very difficult to avoid Chinese made.

But, I may not get to use the slave. After looking around for master cylinders, I couldn't find matching clutch/brake masters of the size I'll need (12/17mm), so it'll be either non matching masters, or, an easy pull for the stock cable

[NeiljohnUK]

Nothing against Chinese here, they make some exceptional stuff, my stator and rotor are made in China.

I use Chinese stators in my bikes, at one tenth the cost of 'factory' Honda, and a three times that for 'factory' BMW, it's a no brainer, and just like the factory stators full vacuum impregnation with good epoxy to stop magnetically induced 'fretting' rubbing through the insulation is worthwhile, still looking for a pump to do that.