Sunday 7 August 2022

The SR500 sidecar - What needs to be done? ALL of it. (Part 2 of 2)

Procrastination is a term, which describes behaviour or more specifically a set of actions undertaken to avoid doing something else. I knew, I had to make some reinforcement plates for the steering head, yet I also dreaded the thought of making them and/or welding them on. (Not sure, which aspect I thought was worse, but they both were rather scary for me.)

So I started with a bit of cardboard and a rather basic shape. (Top tip: if you need a round hole of a certain size, take a small hammer and a nut and just tap the cardboard, that'll cut a perfect hole into it.)

That's the position determined and from here onwards just slowly add all the shapes and cutouts.

I left an about 3-4mm gap to my upper sidecar mount as I wanted to have some room for welding.

The fabrication side of things wasn't too challenging and in order to produce two (close to) identical plates, I welded both future headstock plates (3mm thickness) together and started to machine them.

Welding time - warning these are no Instagram/weld channel welds and admittedly I am not very happy with the way they look. BUT they are definitely functional and to be honest that's what counts. 

Admittedly these pictures were taken before I did even the slightest bit of cleanup on those welds, not even a wirewheel and at least the spot welds and the seam between the two plates was later ground flat.

Not only because it made welding on the inside a lot easier, but also because the engine needed some attention as well, the engine came out. I didn't know it at the time, but the biggest f*ck-up of the whole build is already documented in this picture - when I cut off the hanger for the coil, I got a bit too deep and gauged the frame's backbone. 

And as it's usually mostly hidden - the star of the show, when it comes to holding the sidecar in place, the lower front mount.

Not sure what sort of impulse hit me, but I decided to attack the in-frame filter with a one-meter-breaker bar and guess what... the filter came out. And it was completely clogged with all sorts of old schmoo. So after roughly one can of brake cleaner, it looked like this again.

And *just because* I had the wire wheel out anyway, all the mounting plates got some fresh paint.

I've heard that watching paint dry is supposed to be very meditative, but I had this SR500 engine as an alternative. Even though piston and cylinder came fresh from the machine shop, the oil-consumption was QUITE in excess of one litre per 1000km, more like two or three and as such I expected some carnage. A lot of carnage. 

So I started to go through the engine with the proverbial fine toothed comb.

At this point I was pretty sure that the valve stem seal of the inlet valve was the culprit.

The oil-caked inlet valve would have been quite a good indicator to be honest. But no, all tight and sealing well.

Hmm, cylinder not looking too good. Which is a bit bizarre as that's  a genuine 0km item bored to 88.50mm . (I am so sure about that not only because I double checked it, but also because I got a special deal from a machine shop, which said they had a bunch of 88.50 pistons sitting on the shelf and thus got a very good price on this one...)

... so why does it say 1.25mm (88.25mm) on the piston? 😮 In other words, I know have the answer to a question no one asked. "What's the side-effects of a piston with 0.33mm play in a big four-stroke single?" To give credit, where credit is due, nothing broke or shattered and as the new cylinder and piston setup is already at 88mm and this piston has only done about 400-500km, I am willing to give it a second chance at a later date.

... at which point everything could have been just sooo easy. Also that little piston support was something I made for my very first XT and it makes installing pistons so easy, because the whole piston is supported from underneath and you just have to concentrate on getting the piston and the rings into the cylinder.

Also: Polished valves are awesome - about 3 minutes with a brush and they are clean again.

Unfortunately the camchain came off the lower sprocket, so I had to open the clutch cover and completely forgot that about 1.5 litres of oil were still hiding inside... 

My welding plate will definitely not get rusty any time soon.

Bit of assembly lube goes a long way.

Also completely forgot just how simple the whole top end is on the old 2V XT500 and SR500 engines.

Quickly knocked up a new bracket for the ignition coil. 

And then there was this oil-line, which had this really bad idea of attempting to fight me... turns out I must have bent it somehow, when I took the engine out.

The first start went something like this - smokey, but that's something to be expected, because I am a strong believer in assembly oil. But it also showed that the bushing was REALLY dead by now.

Nothing a bit of POM-plastic can't solve...

And there you go, essentially looks like before and I suspect the engine that 88mm piston and cylinder came out of where taken apart, because of excessive oil-consumption, but hey, at least I tried and with less than 10km on the clock there's still a good chance that the rings will come around again once they've gone through a good few heatcycles. Oh and she's pretty. 😍

Also with all those mods I had to dial in the sidecar almost from scratch. She never handled this well before. So at least the chassis mods and suspension dial-in were a big success.

So, I have two stock cylinders and an almost new 87.25mm piston and an (installed) 88mm cylinder and piston combo with a spare 88.25 piston. Life could be a whole lot worse. 

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