Exhaust part 2

My dad finished the exhaust yesterday, front mount is welded to the pipe and the silencer was made to fit into the back of the megaphone without it being visible from the outside. There is even a reverse cone on the end, which is one piece with the the megaphone, just like the original honda racing mufflers. The silencer has a smaller diameter to fit thru the reverse cone and is mounted with a bracket and 1 bolt from the underside of the muffler.



Also note the paddockstand, it is made to look like the originals from honda, and just a little bit different from the stand I have for my 50. When looking at old pictures, allmost no 2 stands are the same.

The complete bike as it stands now, front fender is aftermarket SS50, just to see how my front brake cable could be fitted, will be replaced by an aluminium fender.
But it is really starting to look like a complete bike.

dirt style 90

Neil sent me a picture of his 90's. He is turning 2 of them into dirt style bikes. The one on the left is a CD90 that he might turn into a racebike later. Nice project that I would like to see more of in the future. Wished I had this much parts to build with.

Spark plugs

My spark plugs came in the mail today.
Don't know if they even make these anymore, but these NOS ones were dirt-cheap on ebay.
20 plugs might look a bit much for the S90, but my dad also uses these in his CB72's, and the cool old display case is worth it to buy in bulk.

Exhaust

My dad did some more work on the exhaust, rear bracket is made and welded to the muffler, front bracket is being built and the pipe aligns with the muffler and the exhaustport. Brackets are made in the style honda used to make them, with a doubling plate on the thinwall muffler where the bracket is welded to with big "ugly" welds.
Pretty hard to make ugly welds when you're used to making things look slick.

Also in the picture, the C320 frame cover I picked up today from Ralph Who is helping me out a lot in sourcing parts and knowledge of the S90.



Front bracket is modeled after a CYB72 megaphone bracket.


and another great help to my project that Ralph had laying around
the engine that will solve all my problems, like a cracked clutch, stripped threads and.....

Ignition

The opening in the S90 frame to get a battery into is pretty small, so I have been searching what possible batteries could fit in there. It was either a 6V-7ah or a 12V-3ah unit. Then I had to make a choice on ignition coils, 6v or 12v and take into consideration that my rev-counter uses 12 volts.
In some old stuff from my dad's CB72's I found some original coils and brackets that looked like the coil on a CS90RSC that must have been raced with factory assistance. And so the choice was made to run a 12V system with battery-ignition without charging system.

Original CB72 Denso coils and brackets


Mounted on the frame, not on top of the engine.


Holes drilled from the inside to clear the internals of the frame. Bolts will be replaced with hex bolts.


Painted in the correct colours the shape of the bracket stands out better, and now I can even recognise the shape of the top of the bracket in the old RSC pictures. I would be surprised if honda used something else then CB72 coils for their RSC.

Front brakestay

As seen in older pictures, my front brakestay was a triangle with some parts blacked out with a waterproof marker. The brakestay was made a long time ago for a project that changed so this wouldn't fit anymore, but now it came in handy for the S90. It was still a triangle as would be made for european bikes with grimeca or ceriani brakes, but I wanted it to look more like an original honda brakestay.
Old honda Racers had steel lower legs, with the brakestay mounted to one bolt, that was mostly on the rear in the middle of the lower leg, like the early CB72 also has it. Later bikes had aluminium lower legs like the S90 with 2 bolts for the fender, in that case the brakestay would be mounted to the rear bolt which was M8 instead of M6 for the fender.
As S90 lower legs are aluminium with 2 bolts, I decided to copy the later style of brakestay, only the S90 has only M6 bolts, so both will be used for strength, but the stay is cut away at the front to make it look like it is only going to the rear bolt.


Allways use the longest bolts possible for the brakestay, if you don't, the thin castings of the legs can break. I had this happen with my CB50 racer because there were helicoils in the holes, therefore only 9mm of the threads were used, luckaly this happened at 10km/h, otherwise I might not have lived to tell the tail.

Exhaust

The day is coming closer that I have to get the bike admitted to the club, so I'm making all the parts that have a major influence on the appearance of the bike. Now that is the exhaust.
At a swapmeat I picked up a header from some italian bike that will be altered for the S90. Nice diameter so the exhaustgasses can flow out freely.

A while back I bought some raw megaphones for the 50 racers and this project, I hung one of them on the bike with some wire to get the position figured out.
A bit too long, so it will be cut at the black line.

And with the tank and seat on there (still not mounted) it is really starting to look like a complete bike. I don't think I will have problems getting it admitted.

rear sprocket

The rear sprocket on the lathe to make it fit the s90 sprocketcarrier, notice the little strips of aluminium between the teeth and the jaws.

fitted, with a chain and front sprocket
Have to get some original locking washers for the nuts, which are extra thin. and still want to make some holes in it to make it look good and save some more weight.

BMW new seat

Today my dad and I went to a swapmeat, we picked up some nice seats for his BMW sidecar racer.
Now you can better see the lines of the fender. much nicer then a big buddyseat.

new parts

Went to my local honda 4stroke specialist this evening to pick up some parts I ordered. I didn't even expect this to still be available, but it was, an original S90 exhaust flange:

The exhaustpipe will be homemade, same as the muffler that will be looking like the original megaphone, but will have some dampening as we are only allowed to produce 105db.

Also ordered some real racing parts:

Offcourse it is possible to drill a hole in a standard drain bolt, but these are worth it, if only for the funny label on the back saying that it is not legal to use this racing part on a roadbike.


More news later, as I ran into Ralph from http://chalopy.blogspot.com/ who had some nice parts leftover that will come in real handy for my RSC project.