UK Brat Build (Engine first)

[Paulrxs650]

Got the casings and barrels back today. The barrels are left bare aluminium and the casings and head have been power coated gun metal grey.

 

[Paulrxs650]

Working off the Christmas pud, a little work today, mainly preparatory. The powder coating process has let a little coating onto some areas, whilst not machined faces, definitely those need to be perfectly flat. For example the cylinder head stud facings.

So, I decided to machine all those surfaces flat and get the Dremel out and ensure that any excess or interfering coatings were removed.

A bit of time spent restoring the tappet cover studs was well spent. Years of abuse and the powder coating took their toll.
A bit of a before and after

Popped the rockers back in but not before a good clean on the wire wheel and some fresh oil to bed them in

While the Dremel was out, I gave the cylinder head a final clean and polish and a final valve lapping, ready to go back together tomorrow

.....and all the parts are starting to assemble

 

[Paulrxs650]

A bit more progress today. I started on the head and noticed that from the factory, there is a significant lip that is present on the inlet ports. So, with my new Dremel, I ground out some material to give the charge a smoother passage on its way in.

...and after

After a good clean out, I reinstalled the valves, springs and collets along with new valve stem oil seals

I’m waiting now for a new set of stainless bolts for the cases and head. So.... I thought I would put together the hydraulic clutch. It’s a slave cylinder from an Aprilia which has a mount that's almost the right dimensions to fit into the aperture left by the original worm gear.

First we have to remove its legs and machine it true

Then to mark up the holes, drill and tap to M6.

.... and we’re done for now. I’ll need to measure up for a new pushrod but I’ll do that once the engine is back together.

A little clean up and tidy for the cam chain adjuster mechanism too..

After.....

I noticed there was a little spacer / spring retainer missing, so I machined one up

 

[member28833]

Very Nice work! Really like that head intake passage cleaned up

 

[650trader]

The little spacer was once a copper washer 341-12232-02 then replaced by a special steel washer
sandwitched to rubber ( tensioner rod damper) 2H0-12232-00

 

[Paulrxs650]

Thanks Machine. Yeah, it just tidies up what is otherwise a well made intake. It only took 10 minutes but should have a positive impact

 

[Paulrxs650]

Thanks 650trader! I remembered one from a few years back was copper, so you’ll be right there. I had some aluminium in the lathe, so I thought I’d knock that out quick.

 

[Mailman]

You sure do nice work! This bike is going to be a looker!

 

[Paulrxs650]

Thanks Mailman! I could actually get stuck into a full build but I have no space. Never mind, the engine will do for now...
I will have quite a bit of machining work to do after the build, so there’s plenty to do. I noticed certain parts like the sump plugs, neutral indent, rocker caps etc are all steel. I am planning to machine all of these out of aluminium. I’ll have to remember to weigh everything before and after

 

[Bewarethemoon]

Hi Paul,

I’m really enjoying following your progress, especially all of the machining you’re doing!

I’m having a lot of parts on my build machined from Titanium.
So far front & rear axles and accompanying spacers, swing arm pivot tube, brake calliper pistons and rocker shaft plugs.

Daniel.

 

[Paulrxs650]

Hi,

Wow titanium! Taking it to the next level there. Sound great, would love to see it

 

[Bewarethemoon]

Hi,

Wow titanium! Taking it to the next level there. Sound great, would love to see it

I’ve not taken a photo of the pistons & rocker shaft plugs yet but then it wouldn’t be the most exciting so maybe we’re not missing much?

 

[Jan_P]

Thanks Mailman! I could actually get stuck into a full build but I have no space. Never mind, the engine will do for now...
I will have quite a bit of machining work to do after the build, so there’s plenty to do. I noticed certain parts like the sump plugs, neutral indent, rocker caps etc are all steel. I am planning to machine all of these out of aluminium. I’ll have to remember to weigh everything before and after

Sump plug in Aluminum I would Advice against that ---this is a rather large ( if it is the 2 I believe ) plug and needs a high torque if copper washer is there.
And the plug goes in and out every season
And when ( if ) the head gets round it can be difficult getting --- Out
Vice will only deform it more .. As will trying to cut a slot for a screwdriver.
I did this on a Honda Fireblade last summer.
Tried a torch.
It was close that i needed to take down the sump. To Drill it out
Which for XS650 perhaps is simpler.
I Managed to solve it drilling a perpendicular hole in . The damaged head.
Inserting a Philips Screwdriver in the hole and hitting on the screwdriver with a hammer.
So it popped loose.
At least those steel plugs can sit really hard.

 

[Paulrxs650]

I’ve not taken a photo of the pistons & rocker shaft plugs yet but then it wouldn’t be the most exciting so maybe we’re not missing much?

View attachment 181534

Very cool indeed! Unfortunately, I don't have access to any titanium, so I'll just have to make do with alluminium!

 

[Paulrxs650]

Sump plug in Aluminum I would Advice against that ---this is a rather large ( if it is the 2 I believe ) plug and needs a high torque if copper washer is there.
And the plug goes in and out every season
And when ( if ) the head gets round it can be difficult getting --- Out
Vice will only deform it more .. As will trying to cut a slot for a screwdriver.
I did this on a Honda Fireblade last summer.
Tried a torch.
It was close that i needed to take down the sump. To Drill it out
Which for XS650 perhaps is simpler.
I Managed to solve it drilling a perpendicular hole in . The damaged head.
Inserting a Philips Screwdriver in the hole and hitting on the screwdriver with a hammer.
So it popped loose.
At least those steel plugs can sit really hard.

Hi Jan P,

Yes, I know where you are coming from, with regards to the aluminium sump plugs. In this case, I plan to use fibre washers and the torque value won't be that high. I have changed to aluminium several times in the past and most race bikes I have had, were all fitted with aluminium sump plugs.

So, I'm confident all will be well.... there's only one way to find out

 

[Bewarethemoon]

Very cool indeed! Unfortunately, I don't have access to any titanium, so I'll just have to make do with alluminium!

I have quite a bit spare? I don’t want anything for it, if you fancy a play around, just postage?

 

[Raymond]

Enjoying watching this one. Huge progress already, given the state of the engine when you got it. Mole grip marks on the cylinder studs attest to the, uhm, mechanical abilities of POs.

 

[Paulrxs650]

I have quite a bit spare? I don’t want anything for it, if you fancy a play around, just postage?

That's very kind of you. I'll let you know

 

[Paulrxs650]

Enjoying watching this one. Huge progress already, given the state of the engine when you got it. Mole grip marks on the cylinder studs attest to the, uhm, mechanical abilities of POs.

Hi,

Thank you! Yes, very much so, I noticed that... along with everything else as I stripped the engine. A big fan of bathroom silicone too

 

[Raymond]

Hi,

Thank you! Yes, very much so, I noticed that... along with everything else as I stripped the engine. A big fan of bathroom silicone too

OMG Bathroom silicone! A few years ago, rebuilt a 1970 Triumph TR6 650 twin. QD rear hub. Except it wasn't quickly detachable because PO had practically filled it with white bathroom silicone. I could not believe how much I removed once I got the halves apart. An attempt to reduce free play, methinks?