first turnover

Today, the S90 had its first turnover, with thanks to the gastank lent to me by Ralph.
It was strapped at the back, with an SS50 tankmount rubber, but atleast it fitted at the front, as the frame is wider then the SS50 tanks I have.

Of course it didn't start right away, I didn't have spark.
After checking just about everything, it turned out to be dirt and/or conservation between the points that needed some sandpaper instead of the normal filing with a nail file.
After that was done, It started reluctantly, telling me that it wants some work done to the carb to get it running properly. But it sounds potent, a little too potent for a sunday afternoon in a rural area, so we took it back inside again to continue with jetting another day, after I took some pictures.

Next to my moped it is just a small bike.

tough choice

Yesterday (saturday) I had to work until 2, but after that I felt like taking a ride on the BMW. but when I came back to the workshop to change back to another bike to take home, I had a difficult decision to make... which one should I take home:

I decided on the SS50 (middle) and It will bring me to the workshop again today, so I will have the same "problem" today.

swapmeat today

Today, my dad and I went to a swapmeat called "vehikel" and found some nice parts, mostly small things, like a couple of bolts I needed for one of my SS50's, a BMW R50 headlight holder and a length of rubber profile for the Oudshoorn BMW seat.
At one of the BMW stands, I found a footrest in a bin, one of maybe only 20 made for the Oudshoorn BMW's, my dad only had one with his bike, but what are the odds of finding a second one?
He probably won't use it as they are very low, but it is just nice to have the complete set.


And I bought a set of tyres for the C110. Front tyre mounted on a rim just to see what it would look like, as it is a cheap rimprotector until the bridgestone 2.00X18 is back in stock.
Yes I will change the wheelsize to 18" with 1.2 shouldered alloy rims and skinny tyres, not original, but looks damn good, I've seen it on a japanese bike.

rocker trouble....solved

This weekend I was at my local honda shop, again... and picked up some original rockers and small parts in case mine couldn't be rescued anymore.
But after some grinding and machining, the old lightened ones are saved, let's just hope they don't break.
Compared to the originals you can clearly see the weightloss, about 5 grams per rocker.

And then of course I also had to lighten the rest of the parts for the real racing feeling. lightened the valves by about 2 grams and valve spring retainers also lost 2 grams each.

Installed in a nice clean head:

The cylinder it will go on, 45mm bigbore, I suspect it to be a modified CD125 piston in 4th oversize, I bought the kit as is.

Headgasket needed to be changed because of the bigger bore, so the inner diameter is a bit bigger then the one that was in the gasketkit, but also the thickness was increased to lower compression to about 10,3:1
With the bigbore kit, the original compression of 9,5:1 would have been raised to 11,5:1 when using an original headgasket, this is a bit much with modern 95 octane fuels at the pump.

This is the result of today, a finished engine, so far.
All bolts have been replced with original cross heads, and all parts I had are mounted. Still need some oilseals and a few bolts for the headcover to complete this, and would like an ignition with cover, but I could take that off my other engine for now.

The oil-line goes directly from the engine to the head, not through the carb, as I might mount a different style carb to this motor at some point.

rocker trouble

I took the rockers out of their cover for the first time, as you can see from the picture, someone has done some work on them with a grinder, probably to lighten them.

But it doesn't look real professional, and when looking at the adjusternuts, you would really say it was a crappy job.
both nuts didn't fall flat to the rockers, but grind in the corner, exhaust being the worst:

So I will have some work to undo this, I will have to lighten the rockers some more, but in ways I am not so sure about, so I hope they will not break when I'm finished with them and doing 11.000RPM.

more valve covers

Found these at my local honda shop this weekend:

To ad to my collection of valve covers:

If someone needs covers like the last ones in this picture, they still had a box full of them, on the bottom of that box I found these chromed covers and some strange red anodised alloy cap that I plan to modify with a small window, so I can see my lightened valve spring retainers rotating. Just for fun.

C110 engine build

The gasket set is in from the UK, thanks to ebay, so the engine could be put together again, and that is what I've been doing this weekend.
As said before, the 5speed gearbox wouldn't fit, so the original 4 speed has gone back in, it was in great shape, so no work needed there, only some new bearings. The same applied for the crankshaft, new bearings and a cleaning to get rid of the old castrol racing oil.
As this engine was used for racing, there was no kickstart shaft, I didn't find a complete new unit (yet), so I've decided to keep the racing pedigree alive and block off the hole with a nice alloy plug.
The alloy clutchplate had some bad grooves in it, so I replced it with a new one I had laying around, together with new steel and lined plates, this should work fine again.
Also mounted the breather unit to the clutch cover, together with the blocked kickstarthole, this gives a nice racing-look.


After this I mounted the 45mm cylinder and piston, so I'm ready for some head-work.

To complete this motor I will need to find some more parts, because I'd rather not cannibalize the running C110 engine that is now under the bike. Enyone who can help me with a clutch adjuster cover, ignition and ignition cover? And if possible an intake manifold and carburetor?
Although I'm thinking of putting on a bigger carb, should be 1960's kei-hin, with a racing look, something like a CB160 powerjet carb, if I can find it.

And don't mind the allenbolts, they will be replaced with original crossheads, will be ordered together with oilseals and some other parts still needed.

Beemer out of the corner

the weather is getting better, and sometimes I really feel like riding, but the beemer needs work, so "let's get to it" I thought.
I cut some material from the rear fender, looks a lot sportier then the original.

And hung the fairing on the bike, to get an idea of what it should look like.

Will need stiffer front fork springs before I can fit the fairing, or it will hit the front fender when I mount it where I want it to be.

breather

The S90 has a nice breather with labirynth dipstick, but the rules say I also have to have a bottle to catch any oil coming out, if anything were to go wrong.
I couldn't decide what to do, it should look a bit retro, maybe an old oilcan, but what I found was too big. This is a small bike, it should have a small bottle that does not interfear too much with the lines of the bike.
When holding some bottle's upto the bike, this is what I came up with:

Generic plastic bottle hold by a honda inletrubber-clamp off a cb450, resting on the brakelightswitchmount (anyone for scrable?)

Also the electrics are finished,
might be running them inside the frame, but for now this works, I've seen less pretty solutions on original old RSC pictures.

It is a racebike, it should be functional, this can mean it will be a bit raw, but I like that on old racebikes.
I'd rather see a bike, fresh from the track with ducktape and lockwire repaires then an over-restored one.

This is how my bike looks now, just need to make a tank.... like it's nothing.
Then fit the seat and a fairing.
Or number plates, as it would be a shame to hide the mechanics.

electrics

To get the 90 running, at least for a testride to see if the engine works, I need to do the electrics of the bike.
Not really much to do, but I want to do it right, so it will be easy to work on in the future, if I have to take out the engine, or remove the rev-counter.
As I will be running a battery-ignition system, I need an on/off switch. I was thinking of a toggle-switch, but I couldn't find one, but I did find an old SS50 ignitionswitch, so I decided to make a bracket for that, so it could be mounted somewhere in sight and accessible when sitting on the bike.
So the original S90 igniotionswitch-hole was not an option, I want to see if I have the ignition on when I am waiting on the startline for the flag to drop.
Once I pushed the CB72 for about 20 meters before I remembered the ignition.......

This is what I came up with for the RSC90:

The key will be secured with safety-wire so nobody steals it in the paddock, and also to prevent it from falling out, as this was a very old switch, the key can be taken out even when it is turned on...oops

The reason why I replaced it on my SS50.