XS400 to 450 Project (part 3) - a boring job

No really. Boring the cylinder block for the liners has got to be one of the most annoyingly boring jobs in this whole build. Each pass was 0.25mm on the diameter, because of the long boring bar and the resulting tool-chatter I had to endure.

Let's start with the aftermath: Looks like a lot of swarf after boring ? Check the last picture...

Now you know, you did a good job, when both holes are within 0.01mm. (At least that's what the internal mic said, i.e. it's below the instrument's accuracy, I presume!)

So this job starts, where the last one left off. And the it's a lot of iterations of the same really...

Bored and chamfered.

 Now that's what I call swarf... and I cleaned it up half way through the job!

Bore for the liner is now bigger than the case mouths. So that's the next job to do. 

Oh and as I said, it was a rather boring job...

XS400 to 450 Project (part 2) - Removing cylinder liners

Now this is my very personal recipe for crepe á la performance: Take a well aged cylinder block, put it on some stands and gently heat it in the oven to two-hundred degrees for thirty minutes.

Some weight atop the liners does speed up the process.

Wait for the noise...

The press-fit of the liners in the block is just a mere 0.05 to 0.10mm. (This will become quite important later.)
 

XS400 to 450 Project (part 1) - Introduction

In classic bike racing 400cc is a nasty displacement: Too big for the 350cc class and just not beefy enough for the 500cc.

So what's the most logical thing? Go big. Unfortunately the XS400 series started out as an XS360 and was bored out to be more competitive. That said, a 15mm gudgeon pin is definitely lightweight, but not exactly durable and the conrod's small end is a bit flimsy to put it mildly and has a distinct tendency towards deformation.

Luckily a bit of research yielded some very, very interesting results. Now Suzuki's GS500 E is a pretty awesome parts donor, its 74mm diameter pistons being a nice upgrade over the stock 69mm items. With bore and stroke being rather close 52.4mm on the XS and 56.6mm on the GS500 E the pistons are actually pretty close in their overall dimensions.

Now a bit more internet research yielded an interesting result in the shape of FJ1100/1200 and XJR1200/1300 conrods to lower the pistons as the compression height of GS500 pistons is a tad higher than the stock XS400 items.

XS400 cylinders in the back, GS500 in the front.

An otherwise stock XS400 crank and two XJR1200 conrods in the front.

The money shot: The new piston is almost bigger than the bore in the cylinder, with the sleeve removed!

The XJR1200 conrod on the crank.

... and installed.