Monday, 18 January 2021

The XV sidecar - start of making a sidecar subframe and a plethora of other things (pt. 5)

Let's start with the biggest morale booster aside from firing up a bike for the first time and that's being able to sit on it for the first time. 


Assembling the bike up to a certain point has definitely been necessary, but the fitting of the tank (when the picture was taken) was hopelessly premature. But then again it felt incredibly good to sit on the bike.

The sidecar-swingarm-wheel-axle is about the right length and also 20mm so the wheel went straight on.

Laying out the sidecar - I wanted to stay within a track width of 1200 - 1300mm, sidecar wheel lead of about 300mm and about 15-20mm of toe-in.

The numbers achievable without any incredible handstands are 1280mm track and a lead of about 320-330mm. Toe-in will be set once the actual bike is built, but I plan to build it with 0 frame-wise, so I can set it up as I please once it is done.

Next job was to tram my milling vise and make the first bits in the lathe and mill. 

Added some pads to have more contact-area between frame and subframe-mounts.

Obviously the roundstock needed some flats for the nuts to sit on.

The adapter installed on the front cylinderhead.

Originally I wanted my bends to follow my engine very tightly, but to be fair, it would probably have given me next to no benefits in rigidity and less more work and the problem areas with the exhaust would not have been addressed this way.

I said, I wouldn't TIG-weld the subframe and guess what... here I am happily TIG'ing away.

Just to give you an idea of the size of my workshop... that's a 3m bit of tube. Cutting stuff got a bit tricky at times.

And here's one of the two downtubes (test-)fitted to the adapter.

The lower mount will be included (boxed in) into the downtubes. Due to lockdown I had to turn down 35mm roundstock to 24 over a length of 130mm. Definitely not a fun job as due to the cold the belts in my lathe are rather slippy.

Then I realised that in order to work out where the rear lower sidecar mount would go, I would have to fit the mufflers as it feels like everything is fighting for the same spots on the bike.  

In the past, I would simply have cut off a bit of M8 all-thread, drilled and tapped my mufflers and then welded them in. But not this time. Now as you surely know, stainless has the nasty habit of eating taps for breakfast and my M8 tap is as dull as can be. So I drilled 6.5mm holes (after fruitlessly trying to tap into the exhaust) and turned the stubs to 6.55, so they would be a gentle press fit and then welded them in. 

And there you go. She's looking more and more like an actual motorcycle every time.  

So what's next?  I need another spacer for the lower front mount on the other side and then this section can be completed rather quickly. After that the sidecar frame will (for the first time) get attached to the bike and then I'll see what the lower rear mount has in store for me. Lower frame and center-stand will undoubtedly need a modification and now that I know how the lower front mount is supposed to work I know I will be able to fit an oil-pressure sensor to the engine case. (I dreaded it would get in the way of the spacer.) Unfortunately this means the engine has to come out once more and I have to do some aluminium welding to fit the bung.

Friday, 8 January 2021

Estimating horsepower via aerodynamic drag

I lately had some fun and felt in the mood for playing around with numbers a bit. The idea was that highest achievable top speed is relatively easy to measure and even though there's a series of factors at work, the main being aerodynamic drag. 

The idea is, when your bike achieves topspeed on level ground this is when its horsepower and the force working against it, even out. So with the topspeed v^2 being known, rho is generally assumed to be 1.2 for air and the only number I was able to find for Cd for a motorcycle was 1.8. You can play around with the cross-sectional area a bit, but a frontal shot of the bike with yourself on it should give you a pretty good idea. I ended up estimating it to around 1.3m2 for my TR1 with me on top of it. 

So I played around with a spreadsheet a bit entered the numbers as above and lo-and-behold got some numbers.

A whopping 71hp at the wheel (casually rounded up for bragging rights), which funnily enough is spot on with what the factory claimed for a TR1... Now I know that my calculation figures in 10 percent transmission losses, but no frictional losses, which at this point might be quite some, especially considering the skinny rear tyre, so the power-rating at the crank might be rather irrelevant. 

Really curious what the dyno will spit out and show whether this is a usable approximation or not.

Friday, 1 January 2021

Project outlook 2021

This is less of a new year's resolution and more an attempt to plan for what to do in the coming year. 

Let's start with my own bikes:

XV-sidecar (still unnamed)

Obviously finishing the XV sidecar will be a priority for the first one or two months of 2021. At the point of writing it's on its wheels and I plan to do a swan-dive into building a subframe and subsequently an exhaust for it. Geometry-wise (as some will ask surely): track-width is between 125 and 130cm, lead is spot on 30cm and toe in is 5cm on 250cm and yes the sidecar will be unbraked. Never needed it on the XS-Triple-sidecar anyway.

Bumblebee the Everyday-TR1

Will get a new exhaust, because the ever-so-social Mr. Nick has bought my current one. The new exhaust will be more or less be the same as the current one, but I will also build a second center section with t a bigger diameter in an attempt to increase top-end performance a bit more. Also I have a reground camshaft from Webcam coming in some time in January and I am currently rebuilding a set of XV750SE heads, which I want to weld up and modify to have a 3 degree angle on the squish-band. The idea behind that is, I could increase the compression a bit and still get away with regular fuel. Other than that just some maintenance like a new brake-pump and a fork service and obviously repainting the fuel tank.


This will be a bit of a bigger project. I am starting to lean towards installing the old 500 4-valve for now to make it usable again as overall the performance of the 600 left a lot to be desired even with all the new components. I fully expect the Wiseco 96mm piston to be kaput, I really just hope it's not the crank that has taken a hit. Aside form that I have all the tubing to make a proper pannier rack for it and most likely I'll switch the harder Tenere shock back for a softer (lower-mileage) XT shock.


On the penultimate day of 2020 I received a parcel, which said "Hydraulic Press 12T" on the outside, so I guess, I'll have to make some tooling and finally get that crank done and then throw the bike together and see how it goes. I might actually consider selling this one or convert it to be at least theoretically usable on the road.

Turbo TR1

I bought an AMR500 for it and I still have enough parts to make a new Turbo-Kit. I guess this will be a Summer project, unfortunately I have to admit this has to take a bit of a backseat compared to some other stuff.

XS Triple Sidecar

Once the new XV-side is up and running this one will be for sale including a lot of the parts that I have for it. (Some interchange with XV and RD stuff, those parts will obviously stay.) The engine needs a bit of a cleanup and the bike some cosmetics before being sold off, but other than that she was a good girl for the time being.

And then there's a shorter list of my dad's stuff that I want to take care of, which is a bit shorter in the number of items, but the actual work is probably not to be underestimated.


My dad's Bandit 1200 is due a proper service incl. adjusting all of the valves and I secretly hope we can get away with not overhauling the 6-piston Tokicos for another year, because the bill for all the parts required would be rather hefty. 

Goldwing 1200

This needs assembly and then an exhaust by yours truly. It's really more a case of "get your arse up 'n' do it" kind of jobs. One of the bigger tasks will be to get rid of the integral brakes as neither my dad nor me kind of like those a lot. 


I have to get a set of VM34s and make a decent stainless exhaust for it. The suspension is a lot better than I initially gave it credit for, but the engine is massively strangled by its stock components at the moment. The ignitech helped a little with the power curve and as such I somehow foresee, I'll daily this for a few weeks at some point to dial it in with the new carbs. (It's a fun little bike, once you simply accept the fact that you absolutely have to thrash it, like it is going out of style, it's even rightfully considered quick.)

Moto 6.5

Should be good apart from sorting out the battery drain issue.

Pretty one (XT 500 4 valve)

Could probably do with a service, but other than that I consider this one to be in perfectly usable shape with little to do in terms aside from a bit of regular maintenance.

Other projects on the list:

A new workbench

My current setup is cobbled together from my old workbench (good) and a folding table (terrible), which doesn't lock very well and is wobbly as sh*t. Also there's about one extra meter of workbench I can fit in there and that's a world's difference, if you only have around three meters in total at the moment.

A new mill

I have set my eye on the ZX7045's little brother, which is mostly identical except for a MT3 spindle, which would allow me to re-use my tooling. As it has the same footprint and mounting hole pattern it should simply fit on my current stand. Admittedly I am also constantly on the lookout for some 626-type mill or something a bit older and less home-owner but the small and clever stuff rarely comes up for sale. 

Rhino lathe

Needs two new spindles for the cross slide. One is bent and both are imperial. You get used to it, but it's no fun working this way. Still debating with myself, if I shouldn't throw some paint on the old girl. 

Re-organize my spare part storage

When I moved in into my new workshop over a year ago, my dad donated quite a few storage trays. Unfortunately they are too small and too flimsy and the parts have to be grouped better as during the sidecar build I noticed that I have so far spent about five to six hours in total looking for parts that I absolutely knew I had.

So that's it for 2021 - should be plenty to keep me entertained. 😉

Wednesday, 30 December 2020

Ever heard of ... BMW R86?

Attention, here comes a bit of smart kit - a BMW R86. This isn't a typo, but a bit of clever mix 'n' match game. So what we started out with here was a BMW R45, which in its first stages of life grew to a much more healthy R65. As you surely know, a R65 runs a 82 x 61.5 mm bore and stroke combination. Now there isn't much wrong with that. It's a bit bland in stock configuration, the phrase "not quite a powerhouse" springs to mind, but it's a very decent commuter.

Let's just say there's no replacement for displacement and we have a little gander at what else BMW has got on the shelves. A BMW R100S runs a bore and stroke combo of 94 x 70.6 mm. I say I wonder if that could be made to fit... (As this is a blog post on the conversion you obviously know the answer already!)

To be fair, there's a German company who sells it as a kit for such a compelling price that I haven't even bothered putting the same kit together myself. 

Four nuts holding the rockers on plus two more holding the cylinders to the heads.

The pushrod-tube-seals were well and true past their prime. They hadn't started leaking (yet), but honestly it would only have been a matter of time.

Splitting heads and cylinders is easy as there are studs poking out, which only take a gentle tap and then release the lot.

BMW gudgeon pin clips are probably made from the toughest and most springy steel known to man, but other than that, there's not much to installing those pistons and cylinders.

Only a smear of sealant around the two top studs is required, the rest relies on the o-ring. Let's see if this is going to leak.

Nice thing about this job, there's only one actual special tool required and that's a special spanner for the exhaust nut.

Fire the old girl up...

... and run her in gently. 😏

A bit of rejetting and some other carb-work might be due, as it originally had fouled one plug, because of a certain lack of synchronization.

And another shot of the bike as I am actually quite fond of it, but don't let Chris now or he'll take the piss of me forever for that statement.


So what's my verdict: if you already have a high-mileage R45/65 said kit is well smart and if the pushrod tubes are leaking, well not that much extra work to do. I admit with the engine being rather short stroked, it would benefit tremendously from a free flowing exhaust and different carbs and if you wanted it a bit more sporty, you'd probably throw in the right kind of cam and then end up with a nasty backroad-scratcher until the cylinders touch the ground. I admit I have just been checking ebay and some other sites for one of those unloved Dutch army R65 GSes... luckily there aren't any for a reasonable price at the moment.

Monday, 28 December 2020

Turbo TR1 - if it ain't blown it sucks

Let's be fair, the last thing I need is another project. But this little gem fell into my lap without asking me for permission.

What you see here is Aisin's finest, an AMR500, named so because it displaces 500cc of air per revolution.

And here it is next to the local standardized gauge vessel for liquids, also holding 500cc.

As the department of motor vehicles only excluded draw-turbo charging, I might just give it another shot with a supercharger and get the old girl on the road this way. Should be good fun either way.

Monday, 21 December 2020

The XV sidecar - building the rest of the engine (pt.4)

Last time we left off with me hoping that the courier service wouldn't let me down. Well, it was more than a week, so probably some things happened. Even without immediately having all the parts at my disposal there was a lot more that could still be done. 

First was to assemble the rotor and mark out the correct position on the teeth (you basically do this blind).

Then clean out the oil-pickup on my oil-pump (Gears were fine, yet still...) and install it

As the 750 clutch was missing some parts, it was about time to overhaul that one as well. Springs were overly compressed and the clutch disks completely worn.

As the center bolt on v-star cylinders is longer (M6x100mm to be precise), I had to get a set of those

The other thing was to clean the pistons, as unlike last time on Bumblebee, these were in very good condition, except for the oil-scrapers, which had failed prematurely. A bit of spray-on gasket remover softens the baked on carbon and makes it easier to clean.

But these are just the cosmetics, not pointless, but mostly cosmetics. The important part are the ring-grooves. In order to clean them, you need an old set of rings, of which you clip off a piece or two and then scrape the grooves until they are free of carbon buildup.

Before scraping, after just a light brush with a SOFT brass brush.

And after an hour of thorough cleaning. As a result now the rings move freely in their grooves again.

With the pistons good to go, it was time to focus my attention on the heads. In general the ports on these heads need a mild touchup and not much more, at least not for road use.

I am fully aware, that polishing valves is more or less pointless... but they look too good AND it slows down carbon buildup on them. 

In order to reduce the seat pressure, I mix and match harder and softer valve springs in the hope of getting a bit more life out of the rockers. 

I know these are somewhat debated amongst SR/XT-users, but I love swivelhead valve adjusters as the grant much longer life to the valve stems due to the greater contact patch. Downsides? Heavier and at some point the ball will wear down resulting in the adjuster screw touching the valve and thus resulting in the adjuster breaking. (Ask me how I know...)


6205-Z single sided, metal-shielded ball bearing instead of the stock ally journal. 


Plenty of assembly lube on the cam.

All assembled. The blue line on the bolt means, it's loctited in. If you can't build an engine in a single go, you have to have some signs for yourself which of the jobs have been tackled and which haven't. (Another one would be my habit of painting the alignment dots on the cam-gear with white paint, so I know the corresponding cylinder has been timed up.)

Tapping the spark-plug thread, because there's not a lot like screwing a spark-plug in a freshly cut and oiled thread.

The camchain adjusters needed some attention too. In stock form the v-star adjusters are too short to work in an older Gen1 engine case with the correct tensioner blades. 

The new buttons have a 16mm head diameter, which is 7mm tall (compared to the stock 2mm) and the bit that goes into the tensioner is 8.6 in diameter and you can basically make it as long as you like, but I went with 6mm. Material was slightly better grade mild-steel (St.52), because that's what I had on hand and it machines lovely.

As I plan to run VM38 carbs on the sidecar and the VM38-200 inlet rubbers don't have any provision for vacuum ports I installed them right in the cylinder heads. The tubing used is 6mm ally tube with 1mm wall-thickness.

And one last tip: if you ever want to use your oil-filler cap again, you will have to trim the bottom most cooling fin of the front cylinder. 

And there you have it: a XV and XVS1100 hybrid.

Not going as far as to say it's ready to be bolted in, but it's quite a bit closer now.