1974 XS/TX650 rebuild

[IntheGroove]

Very nice. Works perfectly...

[hemmjo]

Well that sure did take a bit thoughtful creative thinking!!

[mbshop]

Wow, such a simple thingie ! I assume that just popped into your head and was made in an hour.

[th62]

Some single use thingies: A cam chain holder to stop the chain dropping into the sump all the time. Better than string or wire because the motor will turn over.

A TDC finder. Made of an old plug which I threaded M10 internally, screwe a bolt in place, drilled and tapped that and screwed in a long M6 bolt.

The degree wheel is held in place by three rare earth magnets, it has marking for TDC and other markings 5 degrees apart up to 40 degrees. The short piece of tube, fits in the central hole and is a tight fit around the socket for centering. Once centred, it's removed to give the socket a little wriggle room.

[th62]

When I got the bike the cases had been damaged (read - rooted) by an errant chain. Along with that, the alternator cables had also been cut by the chain and the chain deflector, or whatever you call that thing residing over the gear lever pivot, was also stuffed.
Rather than stick with the original design, I turned up a one piece Delrin bush which slides over the gear lever shaft. Rather than hide the alternator cabling behind the chain deflector, I rerouted the alternator cabling so it is underneath the gear lever shaft and held in place by a P clamp on the starter gear cover.
You may also be interested in making rubber grommets. In the pic you can see the rubber grommet through which the alternator cabling is routed. These, and other grommets, are super easy to make: A fibre cut off wheel and belt sander being all you need. Plus a good set of eyes, or in my case - glasses! The fibre cut off disks are good for cutting the slot, and either the cut off disk or belt sander to shape the outer circumference. Spinning rubber on a lathe does not work well, trust me!
After shaping the grommet, the groove or slot in the grommet is best made by mounting it on a piece of round stock and rotating it against the cut off wheel. Cut of wheels are generally available in two thicknesses 3mm and the much thinner ones used on small angle grinders. Obviously a good, solid rotating base will result in a better groove or slot. With a bit of practice , they are easy to make and come out as good as a bought one. In Oz, blocks of rubber are available from Clarks Rubber. I'm sure in whatever country you live there will be similar stores.
Never buy what you can make.

[th62]

Coil bracket.
When I converted to a single,points system I had to install a dual output coil. I opted for a Honda 750 coil and welded tabs on the frame on which to mount it.

The coil lasted all of two weeks, so I ordered another the same and installed it. It's still ok, but I have heard this particular coil is known for a short life. With this in mind, I found another type, still for a Honda 750, and ordered one. When It turned up, I discovered it was about 20mm longer than the other, so, the tabs I welded on the frame were too close to allow fitment.

So, I cut the rearmost tab off the frame, jumped on the mill and machined this bracket. The bracket clamps around the short frame tube under the main top tube and can be slid forward or backward to fit either coil.

[th62]

When I converted to a single,points system I had to install a dual output coil. I opted for a Honda 750 coil and welded tabs on the frame on which to mount it.


The coil lasted all of two weeks, so I ordered another the same and installed it. It's still ok, but I have heard this particular coil is known for a short life. With this in mind, I found another type, still for a Honda 750, and ordered one. When It turned up, I discovered it was about 20mm longer than the other, so, the tabs I welded on the frame were too close to allow fitment.


So, I cut the rearmost tab off the frame, jumped on the mill and machined this bracket. The bracket clamps around the short frame tube under the main top tube and can be slid forward or backward to fit either coil.

[th62]

I've been ruminating on fitting the TX650.with a hydraulic clutch actuator for some time. Originally a plastic screw type actuator was fitted. The clutch action is a little heavy for my arthritic fingers and difficult to operate as my fingers are fused. At first I modified a spare screw actuator by lengthening the lever, it worked ok, but I'm not a fan of screw type actuators, so, I set about making a hydraulic actuator. I worked out I could fit a hydraulic slave to the inside of the side over with a max piston size of 25mm, requiring a master with a piston of around 10mm. That being the sticking point.

I finally found a master cylinder that 'should' do the job: Its for a KTM and has a 9.5mm piston. Its on order and should be here in a a couple of weeks, along with a couple of banjo fittings. Fitting the slave behind the cover seemed the best idea, as it provided a good solid stop against the clutch spring pressure and would be unobtrusive.

Unfortunately, I couldn't find a clutch master that matches the brake master of the right size, so I've decided to make a feature of having non matching masters. To that end, when the clutch master arrives, I'll polish the body, and then order a radial brake master and polish that, you can't get much different than these two masters.

So, the last couple of days I've spent on the lathe and mill building a slave cylinder and modifying the side cover to fit it: Lots and lots of setting up to ensure the holes are in the right place and everything fits. Lots and lots of swearing and cursing as well.

The piston is phosphor bronze, 25mm diameter and 28mm long, drilled 8mm to a depth of 20mm to take an 8mm ball and the 8mm push rod. Turning and milling the slave was a barrel of fun: I started with a small block of 50 mm 6061, faced it and bored it out to 25mm to a depth of 26mm, then enlarged the first 6mm to 33mm to take a hydraulic ram seal. The seal has a locating lip, so, I had to grind a tool to the ssame shape as the lip to turn a locating groove. And wouldn't you know it, in a moment of senility I turned the groove at the bottom of the 25mm bore, instead of the 33mm seal bore. Oh well, I fitted an O ring to the mistake groove and I'll tell anyone that doesn't know any better the O ring is to soften the rebound.

After the bore was done, I turned the slave around, chucked it and turned down the other end to 29mm for 18mm, drilled and tapped to 10 x 1.25mm, then faced the end.
I had to mill 3mm off the 50 mm diameter end so it would fit in the side cover. Once that was done, the side cover was mounted on the mill and the 26.5mm screw actuating hole was bored out to 29 mm to fit the slave cylinder. The slave was fitted and the two mounting holes marked on the slave, then the slave mounting holes drilled and tapped to 6mm x 1.00 to a depth of 10mm, a mm or two short of the ram seal bore . The slave mounting holes on the the front of the side cover were then milled for clearance to take the allen screw heads.

The slave is mounted where the original screw actuator sat, so space was tight. It's a rather dirty environment behind the cover, so I may have to fit a cover over the seal end to keep it clear of dirt and grease. I'll also have to turn up two half circle Delrin spacers to fill the gap between the slave and the cover to make it look a little neater.

Here's lots of pics of the build.

[tonyfoale]

Very neat installation. Those Japanese screw clutch actuators are horrible, especially after a bit of wear from use. Hydraulic actuation wastes much less of your hand effort.
I get those "moments of senility" quite often.

[nova_robotics]

Very neat installation. Those Japanese screw clutch actuators are horrible, especially after a bit of wear from use. Hydraulic actuation wastes much less of your hand effort.
I get those "moments of senility" quite often.

I had a YZ250 from the early 80s that had to be adjusted about every week. It was brutal. I got really good at removing and reinstalling the clutch cover.