Wednesday, August 27, 2014

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.

Thursday, August 21, 2014


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.

Tuesday, August 19, 2014

and another day of casting

I'ts been a long time ago, so I made some mistakes, but most of this casting session worked out pretty well.

MT125R top yoke, JRP engine covers, CR110 pegs and some CB500f carb covers in CR look.

Tuesday, August 12, 2014

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.

Monday, August 11, 2014

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:

Monday, August 4, 2014


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

Sunday, August 3, 2014

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.