What have you done today, Zephyr-wise?

[Freddy]

Bled the front brakes using Dot 5.1. Half the viscosity of DOT 3 or 4, higher boiling point, fully compatible so the only thing I use car or bike these days.

Replaced the steering head bearings, again. The Motion Pro steering head bearing puller is a gem. Much MUCH easier than anything else I've used.

In the process of adjusting the steering head bearings found a bit the freeplay was actually in the suspension between the inner and outer fork tubes. So replaced the bushes and seals in the fork legs.

[Richard]

Been busy I see, guess it took you more time this time as pulling the carbs...

[Richard]

Did some preparation work for the upside downs. Cleaned up the original triple clamp (is this the proper English word?), removed the bearings and dé-greased the lot. Next is a visit to my local tech goto person to see what can be done...

[750four]

its been a brakes day here today - been sorting out the twin front disks/calipers. They work fine, but nothing wrong with keeping them in good order, is there? Did notice there's the very beginnings of a slight warp on the RHS disk, so had a look to see how much/how easy to obtain replacements - still sitting down with a stiff drink recovering from the shock!

[andye]

I went for a ride. It was a surprisingly Mild & surprisingly nice day.

Richard, or anyone else who's done it themselves. I need to change my steering head bearings. Is it reasonably OK getting the old ones off without the special tools. ?

[Freddy]

Richard, or anyone else who's done it themselves. I need to change my steering head bearings. Is it reasonably OK getting the old ones off without the special tools. ?

Getting the old bearing cups races out of the frame steering head housing is to put it mildly a total BITCH without the correct tool. So difficult you may as well say near impossible.

The problem is you can't get a straight punch through the steering head housing onto the back of the cup due to the angle and minimal exposed lip. The first time I did them I made up a 'curved' punch out of an old brickies chisel. Managed to get them out, put what a pain. Next time bought a cheap made in China 'two haves with a threaded screw to spread them' type tool. You wedge it in the cup, them punch it out. Good theory, doesn't work very well.

Finally bought the Motion Pro steering head bearing puller tool. Piece of cake, works perfectly, and had them pulled out in about 1 minute each cup. Whoever manufacturers the tool has got their dimensions out a tiny bit as I needed to remove a tiny fraction off the bottom blue bit of the tool for it to fit through smaller cup. Just a fraction using the bench grinder.

https://www.motionpro.com/product/08-0545

I have heard of people running a bead of weld around the cups and then punching them out. Never tried it myself, and you'd want to be very accurate. I'd also remove completely from the bike anything with electronic components in it e.g. Igniter, fuse block, etc. Reckon the puller would be way easier and less risky.

P.S. No special tool is necessary to get the old race of the steering stem, or refit the new cups. Just punch the old bearing off (easy access behind the bearing from one angle), brass punch to knock the new cups in, and a suitable small diameter pin punch to knock the new lower race back onto the steering stem (or a suitable size piece of pipe if you have it).

[Freddy]

Been busy I see, guess it took you more time this time as pulling the carbs...

Yep, didn't help that I didn't start to near lunchtime. Would have rebuilt the front calipers as well if I'd hadn't run out of time. That's today's task, together with fitting 0.85 kg/mm front springs to replace the 0.90 kg/mm that are currently fitted. After rebuilding the front forks it is a little 'stiff', but were loosening up after a good run on the public racetrack (a National Park near where I live). Heavily policed on weekends but not on week-days. I'll check out if there is some excess friction in the front end anywhere after the rebuild. I know previously there was less than 10 mm of stiction, so I've got a baseline to compare against.

But regardless have been thinking about fitting the 0.85's for a while with a quite high oil level just to compare (make for a more progressive spring action). Plus it might be a bit easier on the steering head bearings, get sick of changing em. I've had sets of 0.80, 0.85, 0.90, and 0.95 kg springs sitting around for ages from when I was playing around setting up the cartridge emulators in the front forks.

[Freddy]

Would have rebuilt the front calipers as well if I'd hadn't run out of time. That's today's task, together with fitting 0.85 kg/mm front springs to replace the 0.90 kg/mm that are currently fitted.

Done.

One thing I noticed after fitting the 0.85 kg/mm front springs is the turn in to a corner is WAY SHARPER. Rider sag was set identical as previously i.e 40 mm so it can only be because the suspension is more compressed reducing rake, wheel base etc.

Which leads to the interesting question of 'progressive' springs. Just to throw a cat among the pigeons, while the D1 was manufactured with true progressive front spring, I don't even know where you'd buy a set of progressive front springs these days. What are being marketed as 'progressive' springs are not progressive springs at all. They are 'dual-rate' springs. Effectively two linear springs of a different spring rate manufactured as one unit.



Point being, the spring rate of each section of a dual rate is important (a true progressive spring has no rate as no two coils are the same). Just out of curiosity I recently checked with Wilbers to see what dual rate springs they had for a Zephyr. Soft section was 0.70 kg/mm and the stiff section was 1.1 kg/mm.
A 1.1 kg/mm is a VERY STRONG motorcycle spring for a typical weight rider. Expect to have only part of the front suspension travel working if someone fits springs like that.

[Freddy]

Changed the front fork oil from about a 22.5W (mixed by volume) to a straight out the bottle 20W.

After changing the front springs from 0.90's to 0.85's found the rebound damping to be a bit slow with the heavier oil.

[750four]

just noticed a big cube of rubber missing from the centre of the rear tyre ... no surprises for guessing what the job tomorrow will be!