and the season is already over

End of racing season, it went so fast, I forgot to post about it...

so a quick summary of pictures, courtesy of the CRT website. and JanAw as found on the internet.

The SS50(85) behaved pretty well for a new build, some teething problems, but very quick.

The RSC90 got a fairing half way through the season, because I had a complaint of not having numbers on the side...that I didn't have for all the time I rode it. But it was the push I needed to finally start on the fairing as was planned. needs finishing, but the beginning is there.

The C110 gave some trouble too, but at the end of season I found the issue, fixed it and it was running quicker then ever.

another batch

And yet another batch of brand new vintage parts.
Including two of the newest project, a rear backing plate for 110mm Honda hubs, SLS but also in the future I plan on making a 2LS out of it, some preparations for that are already in the mold.
Planning the 2LS for my RSC90, will make the rear hub fit more with the 4LS front CB125RSC hub.



the line-up:
160mm front brake plate, Honda RC styled
110mm rear brake plate, Honda RC styled
CR110 footpegs
CR750 clutch perch
Honda RC styled brake pedal
JRP breather covers
S-monkey oil cooler adaptors
RSC engine cover, meant for a Honda 50, but going towards a 750

the last event this season

Last weekend was already the last event for this year, Giessen, for me the first time here and I like the track a lot. So hopefully we can ride here again next year.

We took a lot of bikes with us, left to right:
-the C110 racer for the oldtimer class.
-CB50 racebike we overhauled for someone to do a couple of test laps in the oldtimer class, luckaly it behaved all good so I could jump on my C110 after 2 laps en do the rest of training with that.
-My dad's old CB50 racer that we had a friend ride in the 50 class.
-My own CB50 that didn't run very well in this experimental phase, took a little getting used to again to rev between 12.500 and 14.500.
-and last but not least, my RSC90, reliable and quick, might just open up the engine this winter to see why it is as quick as this, because I can't really believe how it's doing so well.

after Den Helder

Den Helder went pretty well, the RSC90 ran like a top but once back in the workshop I discovered the cilinder base gasket is leaking some oil, so sadly I will have to open up the engine.


picture from the CRT website
Note the 4LS front brake is back in there and this time it worked.


The longer brake lever on the C110 front hub didn't do what I hoped it would, still pretty much no front brakes and they became really hot, so I decided on making some cooling holes in the hub.



Angled so the rotation of the wheel will create a vacuum to draw out the hot air.


Maybe I want to create some sort of small air scoop on the brake plate just above the lever, but I'll have to put the wheel back in the bike to see if that wouldn't look horrible, and this is now how the bike stands:


Rear brake was terrible also, so swapped some brakeshoes and having everything skimmed to fit again.

On the bench also a bigger front hub, replica CR110 built to match the forks in the past, but I want to try and keep the original C110 hub, it looks nicer.

tachometer

Okay, last weekend was another event, and again I forgot to take pictures, the day is pretty full when riding 3 classes and doing repairs in between.

The RSC90 had a brake problem in training, so I swapped the 4LS wheel for the spare 2LS with homebuilt brakeplate, which performed perfectly.


(picture from the CRT website)

The C110 did really well, only the brakes leave a little to be desired, might be they are too small, or that I can't get enough force into them, so I swapped the brake lever for a longer one to see if that will help for next weekend.

And then there was the CB50, took a little getting used to, as it revs much higher then the other bikes, and now found it annoying that the tachometer wasn't accurate anymore since I had fallen some time ago where the tach had some damage afterwards.
So finally I decided on making another tachometer that would be accurate even in those high revs. and the old one from the 50 went onto a CB72 where it is no problem if the accuracy goes down above 13.000rpm.

Step one, take a standard Honda tachometer and open it up.
Step two, make a little bracket that stops the needle at 3, or whatever you make your custom face start at.


Step three, replace the face, and paint up all the outside bits to the colour of your choosing. In my case black, like the original CR110 tachometers where my face is modelled after.


Step four, put the tachometer back together again, seen here still resting in the cilinder liner that has been modified to become a tach-pressing-tool to crimp the original ring closed again.


and in between, check if it still works okay, these things are delicate, I'm glad this one went well, and also like the completely white needle and black surrounds, the first ones I did were different, but I like this better. Less fuss, more pure racing use.

spare wheel

The spare wheel is pretty much done, just a screen to make in front of the scoop, tested it in my SS50 motorcycle and everything seems to work just as it should.
Testfitted to the RSC90 and the brake anchor fits as it should to both the S90 and CY50 forks that I have in these two bikes.



not a bad look either, but as it only a 2LS, there will be torsion in the forks, which I don't want.

New front brake for the RSC90

With the S90 forks I've had the issue that under braking, the forks twist with the single sided brake. It's not a big problem, but it just doesn't feel that confident.
So what I wanted to do about that, was to create a double sided drum brake. As a test for that I started the homemade 160mm single sided brakeplate to see if a homemade brake could be up to my standards as for rigidity of the plate and so on.

But then I found something online in Japan: an original CB125RSC front brake

It took some time and effort to get it over here, with thanks to the great service of Masato But I got it, a real original NOS Honda 4LS front brake. Dreams come true.

This would become my new brake for the RSC90, a fork brace would have been a lot cheaper to stiffen up the forks but no way as cool as this.
So I started on making all the other little things needed to fit the hub, like the cable splitter:


machined it from billet aluminium, from pictures of the original CB125RSC and RC166 splitters, I just kept it a little bit smaller to match the tiny build of the S90.

I had spokes made to fit my 18x1,50 DID rim so the hub could be laced up.

ah look how beautifully tiny the hub is, only a 130mm but 4LS, making it cute and tough at the same time.

Making brake anchors out of aircraft grade aluminium


And as always, the last step is to make the cables, made from 2 original grey ss50 brake cables that were discoloured just a bit so they match the other cables.


and the endresult, including my newly built bigbore stroker motor:

Brakeplate

A while ago I found a new brake for my RSC90, that I'm now in the process of fitting (pictures will follow) but the old brake has come out and I've also started machining my self cast brakeplate to fit that hub, so I can have this as a spare wheel.



Already starting to look like a real Honda racing front brake :D

bigend trouble

During the last event at Gramsbergen, I blew up the S90, The bigend totally expired causing damage to the piston, cylinder, valves and of course the crankshaft itself.
This is what was left of the bigend bearing, the rest of the aluminium cage could be found all over the insides of the engine.


As I was running a 53mm bigbore kit, I can't just go for a different crank and an oversize piston, so I decided on getting plan B out and building me a stroker/bigbore engine as I had planned a long time ago.
Now built with an ATC110 crank and cylinder that is bored out for an ATC110 56mm bigbore piston, combined with a ported and modified C90 head to fit all S90 internals from the other engine that wouldn't fit in the ATC110 head.
Also in different cases that where bored to except the ATC110 cylinder but still with the same 4speed close ratio gearbox that I ran in the other engine.



Note the extra bolts in the right cylinder head cover, these are for the oilcooler that also has been added this season.

Two bikes running

The C110 came back from upholstry so I fitted the repaired motor and got all the cables and bits hooked up again.
So this one is pretty much ready for the CRT event in Varsseveld





In the meantime the motor for the RSC90 is all put back together again and fitted to the frame, fired it up and it looks like there is a lot less vibrations with this other crank, which I now will be running without any rotor on the crank to reduce weight.
Stole the front fender back from my SS50 motorcycle.
Gave the exhaust a fresh coat of paint to hide some big scratches.
And my dad built me a new paddock stand to go with the new foot pegs.





Just a few little bits to do, like putting my startnumber on the front.

close ratio gearbox, finally complete

My RSC90 is also on the workbench again, hopefully to have it up and running for next weekend in Varsseveld.
The last time I rode it, there were two things that bothered me:
- the footpegs / groundclearance
- the gearbox

As seen before the footpegs had already been changed, but the gearbox was still an issue.
It had problems shifting from first to second gear, ending up somewhere in between, halfway in neutral but totally stuck until you would kick it up and down a few times and finally end up in second.
And besides that, the gearbox had been changed into a close ratio box, except for first, what meant I had a huge gap between first and second.

So now, I opened up the motor, to finally have first gear altered to achieve a full 4-speed close ratio gearbox as near as I could get it to the original RSC90 gear ratios. While in the meantime altering the shift forks hopefully getting a smooth transition from first to second.

I had already found some gears that could become a first gear in the S90 after grafting them onto S90 parts and my dad made it a reality.
My gearbox now has an SS50 second gear made into an S90 first.
Together with the SS50 3rd/RSC90 2nd as a second gear,
original S90 3rd
and CT200 4th gear
it makes the following close ratio gearbox:

1: 17/31
2: 20/27
3: 22/24
4: 24/23

compared to original S90:

1: 13/33
2: 19/29
3: 22/24
4: 25/22

and original RSC90:

1: 18/30
2: 21/27
3: 22/24
4: 24/23

clearly visible, the difference between the stock 1st gear on top and the diameter of the modified shaft.

Also swapped the crank for a different one, because this motor had terrible vibrations, maybe this could be the solution.


Now to finish the motor and get it back in the frame and I'll have to check everything as a lot of parts had been taken out or used for other bikes in the meantime.

home made brakeplate

The latest casting project I've been working on for a while just came out of the molds.

It started as a big chunk of MDF slid over an old front axle.


Then adding some parts cut out of an old front brake plate, kindly donated to the casting process by a friend. And the beginnings of a scoop on the front.


Even though they are still loose parts, it is starting to look like something, and a lot more race inspired then an original 160mm brakeplate.


Smoothing and painting.


allmost ready for casting.


and the inside, made with original parts so the standard brake shoes will fit.


Broke the mold open, first impressions look good, fully formed, although it has some little flaws, but that is the charm of sandcasting.


Fully uncovered, it looks good, just like the original old racing brakes, but made to fit a normal 160mm Honda hub as found in many street bikes, and in my RSC90.


Now to harden it and then machining, what will probably take some time for this first one. But then I will have a plan for the next ones I might just make.

and some other stuff that was cast in the same session:

CR750, CR110 and JRP, more rare stuff from my hands, how funny is that.