The life and times of my 650

[Scotchmist]

Hi all,

I've had my bike for about three years and have been a long time lurker on this forum. I recently realised I have very few pictures that track her development during that time. Seems like a build thread would be a good way of going about it. I've also been prompted by a recent house move from Bristol to London. I've not yet managed to find storage for my bike in London so it's been left behind in Bristol. I thought that starting a thread could be a cathartic process and a good opportunity to get on with a few 'sub projects' that I've got in mind i.e. small assemblies that can be worked on away from the bike. More on that in a bit.

It's worth mentioning that the bike as it stands is a long way from my aspirations for her. When I bought it the PO was part-way through turning into a cheap bobber. It had bar risers, drag bars, a banana seat and the whole bike had been covered in rattle can matt black. I've since been trying to undo some of the worst changes that had been made and to make my own sensible modifications to improve handling and reliability. Unfortunately, my efforts were hampered when the bike blew a whole in the right hand piston after a month of ownership. Being fairly new to bikes at the time I wasn't aware that the PO had the ignition timing set way too advanced. Anyway, the rebuild gave me a chance to replace bearings, bore it out to 700cc and replace the cam chain and guides. This was the state of affairs a couple of years ago.

After the rebuild I took the bike on a celebratory tour of France and Spain clocking up 6000 miles over 5 weeks without a break down. Here are a couple of shots...

My brother and his 1979 Triumph T140 is on the right.

Since then, I've made a few more changes and generally tidied her up a bit. This is roughly how she stands at the moment.

I've made a few more changes recently that I'll upload when I get the chance. I'll also post up some photos of the sub-projects and what I've got planned for the future.

 

[Scotchmist]

Forgot a few things. About 100 miles are returning from my trip the charging system started playing up. After replacing the brushes and rectifier and breaking down a dozen times I gave up on the OEM setup. Instead I put together a homespun permanent magnet alternator conversion. I fabricated the conversion plate using a hacksaw and files out of 6082 T6 aluminium. It took absolutely ages. I helicoiled all the mounting holes for strength. The stator plate, stator and flywheel are all off a Yamaha RD350LC. I used an aftermarket 5 wire, 3 phase regulator/rectifier. The bike discharged at idle with the OEM alternator and now makes 14.1v at 800rpm and 14.6v at anything above about 2000rpm. No problems at all since then.

 

[Scotchmist]

Ever since I've had the bike I've been keen to change the cast wheels for spoked. I finally bit the bullet and got myself an (almost) pair. The cost of spoked wheels in the UK is mad so you can't be too picky. Managed to find myself a lovely NOS rear with a Takasago flanged rim.

My bike came with a rear disk so I needed to do a bit of chopping and welding to make the swap. I'm currently running a braced swingarm that has much larger diameter tubes than standard and is about an inch longer overall. Does anyone recognise what it could be from the pictures? Could it be a TX650 swingarm with aftermarket bracing? Interesting if so as the model never made it to England.

Relocating the torque arm mount from the top to the bottom of the swingarm was a little hairy as the entire swingarm is brazed together. I was a little fearful when welding close to the brazing that the whole thing would melt and fall apart. I made lots of effort to reduce heat build up which seemed to work fine.

Here's a picture of how the bike stands without a seat. You'll notice that my bike is often pictured without a seat. I'm in the middle of making a custom seat and can't stand looking at either the banana seat that she came with or the rotting custom seat I got for the European trip. The photo also shows the newly powder coated mudguards, Ramair filters (UK equivalent of UNIs) and rebuilt forks with boots).

Alas I wasn't able to find a decent front wheel with flanged rim. I'll probably put this on when I get the chance.

 

[nj1639]

Looks great!
Shame there's not a simple rear disc spoke setup that would be a direct swap for the mags. Nice that yer Bro has a trump as seeing the comparisons of the workings of the two different bikes whilst on a trip would be cool.

 

[rusty rocket]

Wow very kool! Sounds like a very fun trip you took.

 

[fredintoon]

Hi Scotchmist,
now you've moved to the big smoke you'll have to learn Cockney and what with already speaking English and Bristolian you'll be trilingual.
And they say Brits are insular?
Nice bike BTW, I like a work in progress. Did you swap in the XS11 front disk or did it come like that?
FWIW, I gave my son a set of wire wheels that I'd swapped onto my Heritage for looks and swapped back for practicality.
He had to go from rear disk to rear drum on his '80 Special and so we had to make and weld on a mounting for the drum brake's torque stay.
We left the disk brake torque stay mount in place so he can swap right back again after he gets sick of keeping the wire wheels polished up nice and scared of having to patch an inner tube at the roadside because he ain't got tubeless tires no more.

 

[Scotchmist]

Thanks for the comments. I think the most interesting comparison between the XS650 and the Trump on that trip was oil consumption! Otherwise, they're really evenly matched. They're also both '79 models. Off the line they're both absolutely neck and neck.

I didn't mind making the disk/drum conversion permanent. I don't see myself going back. Even considering the extra maintenance, flanged rims are a winner. Just gotta get round to building up the front wheel with something matching.

The xs1100 front disk was added by me but will be replaced shortly. I've acquired an FZR600 (3HE) front end that's destined for the XS. I'll keep the stock front wheel, probably modifying the FZR lowers to accept the larger XS axle. I'll run a single Yamaha blue spot caliper with Ducati Monster 320mm disk. Just working out how to make the new front end as subtle as possible. Not really keen on the modern front end look. Other than the brake (which can be painted a nice shade of black), the front end should look fine. The stantions are only 3mm larger diameter than standard and I'm looking into alternatives to the standard FZR top yoke. Pictures to follow...

 

[scabber]

Like the bike. Nice job on the transformation. Good to see your having great fun with it. Enjoyed the pictures of your tour. keep posting your build pictures as you progress.

 

[weekendrider]

Yeah what scabber said. If you want a measurements of the TX750 tube to compare with what ya got. iirc it is about 1/8 inch larger

 

[marp68]

Beautiful transformation.

Regarding the images of the trip you made with the bike, where were the photos of the lake and the mountain road taken?

And it seems you're running longer rear shocks. Are they even more than 34"? Looks great.

Good luck with the rest

/M

 

[Scotchmist]

Thanks again for the comments.

Next time I'm in the shed I'll measure the diameter of the swingarm tubes. It's either a modified TX swingarm or a bespoke item. Does anyone know whether TX swingarms were welded or brazed?

Marp68, I'm afraid I can't remember exactly where the mountain road picture was taken. It's somewhere near the border on the French side of the Pyrenees. Pretty sure it's towards the western end of the National Park. The photo by the lake is just off the N240 between Pamplona and Jaca in northern Spain.

IIRC the rear shocks are just over 13".


So, as I said in the last post I'm looking to swap my forks for FZR items. £45 later...

I'm planning on stripping the paint from the lower legs, shaving the calliper mounts off the left leg and polishing them both. I'm keen on trying to modify the lower legs to accept the 17mm XS spindle so that I don't need stepped spacers (I got the idea from someone on this forum). Seems like a neater solution to me.

I don't plan on running clip ons and have heard that drilling the top yoke is a bit dodgy so I've found myself a Yamaha Diversion 600 top yoke. The two bikes used nearly identical forks and the stantion size, spacing and offset are the same. Looks to me like they're a straight swap. I'll remove the ignition switch mount and casting marks, strip the paint and give them a quick polish. Hopefully, that'll make them look a little less modern.

I haven't got myself a calliper yet but they're cheap and freely available. I'm hoping that I'll be able to find clearance between the back of the four pot calliper and the spokes of XS wheel. Just because I think it looks great, here's a shot of the Ducati disk which has the same bolt pattern as the XS hub.

I've done some calculations and it looks like the Yamaha blue spot calliper will work best with an 11mm master cylinder. After speaking to Pekka on this forum I opted for a master cylinder from an Aprilia SR50 moped. They're dirt cheap (£15 second hand) and made by a reputable manufacturer. I've also got a matching left hand master cylinder which is the rear brake from the same model of moped. This will be the master cylinder for a hydraulic clutch setup that's in the pipeline.
Ignore the bars in the picture below, they're just for the mock up.

 

[XSLeo]

34" rear shocks, wow.
On your swing arm, the TX750 has one very simular to the TX/XS 650. It bolts right into the XS650, was the same length, just built with larger tubing.
As far as being longer, it's not hard to extend, probably done when it was braced.
I like your tour pics.
Leo

 

[marp68]

jajaja... mm it is then

 

[fredintoon]

jajaja... mm it is then

Hi marp,
caption from a cartoon from the day Canada officially went metric.
"That's so we can install these 400mm cupboards on those 16" studs."
BTW, 34 cm = ~13-3/8". 34mm = ~1-11/32"

 

[marp68]

Not my day today it seems...

 

[Scotchmist]

 

[Scotchmist]

As anticipated, I've done very little in the last few months. I do have more time on my hands now so should make a little more progress.

I have managed to make a bit of progress on the forks. There are three main areas that needed consideration; firstly, the headstock bearings; secondly, the wheel bearings/spacers and thirdly, the brake/disk.

So far I've ticked off the first two things. The stem is identical between the FRZ and XS and just requires a swap to the XS tapered bearings. The only other problem I encountered was the depth of the XS frame lower bearing cup. With the tapered bearings pressed to the bottom of the stem the bearing cup and fork bottom yoke fouled. I ended up making a 3.5mm spacer for the bottom bearing. The small size means that the top bearing remains in line with the specific machined area on the fork stem.

In order to mount the XS front wheel I pressed in new bearings with a 15mm ID to match the orginal FZR spindle. I then machined spacers to centre the wheel. The speedo side was machined with a protruding spigot to take up the space between the FZR spindle and the larger 17mm XS speedo drive. I now need to extend the speedo drive housing to mate with the lug on the inside of the fork lowers. As the speedo body is steel I'll probably just build it up with weld and cut a new slot to accept the lug.

Sorry for the grubby picture of the spacers!

Other bits and pieces. I've been working on the top yoke to make it a bit more 70s and fit for purpose. As the ignition is mounted elsewhere I removed the igntion ring and set to work removing the paint and rough cast finish (which took hours!). I haven't gotten round to polishing it yet.

I've also shaved the brake bosses off one of the fork legs and sanded and polished them both. Hopefully should make them look a bit less sport bike and a bit more 'period'.

Still need to extend the steering stops on the bottom yoke, machine a disk spacer and make a mounting plate for the caliper. The caliper itself is off an early FZR 600. I'm using it instead of the ubiquitous 'blue spot' calipers as I think they suit the bike a bit better. The mockup of the parts suggest that a small stepped mounting plate and a c.15mm disk spacer should give enough clearance between the wheel spokes and the rear of the four pot caliper.

Here's a quick final photo of the bike as it stands with the forks mocked up. As you can see I've acquired an early TX650 tank which I prefer the shape of and a roadster seat which may not be used.

Any comments would be welcome especially anything concerning the safety of my proposed wheel spacers as it's the first time of done that kind of machining.

 

[5twins]

Amazing that the two stems match up so closely. The bottom tree is most likely cast and welding that can be very tricky. It might be a better idea to build up the steering stops on the frame. That's just plain steel and would be much easier to weld.

 

[Scotchmist]

Ahhh, that makes sense. I ground the mounting bosses off the front and welded up the holes. It did seem to respond a little strangely to welding. Now I know!

 

[Scotchmist]

Here's the next part of the plan, securing the speedo drive to the fork leg. Here's my first attempt at using a milling machine. Tis a little bit rough but fits well.

I've machined a tapered lug to match the slot in the speedo drive.

This is roughly what it'll look like in position. A friend of mine will TIG it onto the fork leg.