Dot 3 and 4 are basically the same but 4 has a higher temp rating.
There won't be any detectable functional difference between the two.
You could use dot 5 if all the brake system is fresh with no trace of old fluid as it is silicone based and cannot be mixed with the others.

Rob, I just checked mine and it's exactly the same as yours. Fancy making up another spacer in exchange for beer vouchers? I have hardly run the thing hence not noticing any charging issues (battery lives on a Lithium Optimiser). I have a Moto Gadget speedo on the Moto Martin. It was great but when...

Electrex strikes again :( With my increased vigilance on the charging system after the Lithium battery failure and subsequent 1/2 mile push home i noticed the current battery read only an average of 10 volts after the good run out to the Squires meet on sunday. On closer inspection of the Electrex ...

Gs1000s 28mm carbs are a different design to the z1a carbs.
They are similar to the later Z1R 28mm carbs but have a superior pilot circuit with additional fuel mixture screw.
They will work with your 900 engine but will not be original in appearance.

Whereabouts in Lincolnshire are you ?

NONE.
You can use a small bob of grease to hold them in place if needed to stop them going awol when fitting the head.

A pic would help.
The early number pads with no lip were shorter in length than the later ones.

Early engines have no lip.

There are 3 small ball bearings that prevent the gear from sliding along its shaft and they only release under centrifugal force, hence the need for the bike to be rolling before second can be engaged.
They can be removed but the engine needs to be split to disassemble the cluster.

Hope to give the Zed café a decent run out if it stays dry.

You want 1.92 to 1 to equal the original ratio you had with the 18"s.
If you have a chunkier modern swinger then somewhere around 19t front and 38t to 40t rear will help the chain clear the top run.

They will rock on the lobes and the marks only line up with the head once bolted down .
Don't be too worried if the marks sit a mill or so above or below the head as deck height and gasket thicknesses will have an effect.

Looks like the rotor has spun in the past.
Doesn't look too bad though.
A light lapping of the rotor on the taper with fine grinding paste will neaten it up and provide a closer fit.

It is your coils that are the cause.
Those grey coils are only 2.2 ohms.
You need a minimum of 3.0 ohms (Green dyna coils) if you are using a Dyna 'S'.
Going higher than 3 ohms is ok but not lower.

Pigford wrote:Rob - you're fast becoming a LEGEND

Why do I have the sneaking suspicion you are pronouncing that LEG - END