Another CB50 racer almost done

My dad and I have been building another CB50 racebike, as our old ones have been sold, now being raced by friends. Even a third had been built for someone else, who also races it at the CRT. Now we've built a fourth one for my dad to race, mostly from leftovers scattered around the workshop from years of racing CB50's and plans to turn them into CR110 replicas.








Custom Tacho face, original brake and clutch levers, sand cast alloy top yoke, Chrome Honda flip-up cap


Larger 140mm rear hub


140mm SLS front hub

clip-on's

Just finished a batch of clip-ons
Needed a set for the SS50 racebike and another for one of the CB50's that has been sold, but included in that deal was a front end swap.

A bunch of steel pipes


Some more small parts added, almost ready for brazing



after brazing, cleaning and painting


The observant viewer would notice one set missing, that was already mounted to a bike.

Some details not found in modern clip-ons are the closed ends, not with a plastic or alloy bung, but full steel construction, so that after painting, it is almost invisible how the ends were closed.
Just a single 8mm bolt, instead of 2 6mm bolts, just like original CR110 clip-ons, and other Honda's from that era.





Took a lot of work, but the result are some clip-ons that look deceptively simple and yet sophisticated at the same time.

hand made front mudguard

Working on the SS50 racebike again, as my CB50 was sold.

It needed a front mudguard for several reasons
- it looks good and old Honda race bikes had mudguards
- rules say you need to have one if you don't have a fairing (fairing is for the future)
- it can function as a fork stabiliser, needed because of the single sided front brake.

For the fork stabiliser bit, the supports are made out of steel and run over the top of the mudguard as one piece, not the prettiest, but I've seen this on original (race) bikes and it is very functional. And I like things that look functional even if they are "ugly"

The start, a piece of steel bent and cut to fit between the forks and 2 pieces of tube with the ends flattened with a special tool to get those ends just like Honda used to make them. Clamped together for braising.


Braised together and 2 cable loops added, just because, if this were original, Honda might have supplied a 4LS in the RSC kit and the mudguard would have been prepared for it. I will only be using one loop with my 2LS for now.


Parts primed and screwed together in preparation for riveting.


riveted and painted silver with a little bit of clear just for a little shine, to imitate that original look and not to go overboard on the clearcoat as so many replicas these days.

tachometers

Since I've built a new tacho for my 50 this year I got annoyed by the quality of the old prints for the tacho face. So I asked a friend who is good with graphics and has his own company in printing if he could help with new tacho faces, not only the CR110 / CR93 replica, but also an RSC and two different smiths faces, like the ATRC tacho's.
Today I mounted the first test print into an old housing to see what it would look like and how it would fit. Just a few tweaks and then it will be ready for a small production run.



also available will be:
smiths from 1 to 14
RSC from 3 to 15
CR110 CR93 replica 3 to 16

all to fit in original honda 1:7 tacho's as used on most models up to 500cc

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.

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.

Lots of racing this weekend

Yesterday we had a race in Nunspeet, I had a lot of trouble getting the RSC running correctly, fiddeling with main jets, but at the end of the day I found the right one. All the symptoms directed me to a bigger jetsize, but smaller was the answer.
I did have a lot of issues with the gearbox though, after the clutch exploded, the gearselector arm was bent.
Pictures can be found thru the Nunspeet bike club website (click "classic race")
What do you know, If you click the 2nd link, the first thing you see is me....

picture thanx to: www.naomischolten.nl
More great photo's can be found on her website.

My dad rode his CB50 with 75cc engine, also having gearbox trouble, first time an original honda 5speed doesn't work the way it should, they are normally pretty indestructible.

My RSC engine was opened up today to fix the gears and it seems to work a little bit better now.
So the RSC is allready on the trailer again for races tomorrow in Varsseveld.
I didn't want to ride the 250 or 500 there, so we got my CB50 out and put it back together again, as some parts were "lent" to other bikes.

I hope tomorrow all goes well, the 90 gearbox should show improvement and the 50 has an experimental camshaft setup.

line-up

The weather was nice, all the bikes were at the workshop and I had a camera with me...just felt like a "kodak moment"

all my honda's lined up, and in the background you can spot the Beemer.

Long stroke experiment

Sadly the experiment didn't turn out to have a big effect.
After a lot of fine tuning it might give a little bit more then the current short stroke motor, but not enough to make a real impact in the 2stroke dominated 50cc class. So I'm thinking of quitting the 50cc altogether to focus on my RSC90 and maybe a CB72 that I've been trying for the last two events.

For now the 50cc has been converted back into a short stroke, with some minor adjustments to the head, valves and camtiming to get power at higher revs.
Next weekend is the Honda-day with a dyno, lets see what the little 50 has to give.

Long stroke experiment

A new experiment to get some more torque out of the 50cc engine, as it is originally a short stroke, at 35,6mm with a 42mm bore.
Now a test using an XR75 cranck wich has a 41,4mm stroke, just like an SS50.

Cylinder is sleeved to get to a 39mm bore, combined with a GB2 piston, originally of an engine with horizontal cylinder.

Tomorrow its first run....

First event of the year

Last friday was the first event of this year, in Nieuw Vennep there was a section of industrial area where they created a track. In the morning we had some rain in training, but in the afternoon for the first heat the sun began to shine, with the second heat the track had almost completely dried up. I had to get used to the CB50 again, as this was the first ride since last season, but I've got the hang of it again. Some pictures with thanks to Lea Langezaal.

Me (75) chasing Cor on his sachs (57)




more pictures of this event found on the CRT website

Racing at Enter

Last saturday I raced my Honda CB50 racer at Enter in Holland.

Had some problems with the clutch, just like the week before in Veenendaal, I hope I can get new clutchplates this week for the races in Basse and Purmerend.

Otherwise I will have to ride like it is now, not to big of a problem, only when we have a red flag and have to do a restart.

My bike:

Me at enter and the kreidler I just passed