#14 Raceknuckle

Carb again ... using the two barrel Weber DCOE40 causes two problems with this bike: first it is a really fat carb and occupies lots of room on the right side. It's a problem while driving since the leg or knee is covering the stacks. Also it's a cosmetic problem because it gets crowded as the exhaust will be on the same side.
Attaching the DCOE40 on the left simply looks weird and the manifold is too short (loss of torque).
Given this I decided to use a standard upright assembly which in turn means, exchanging the DCOE40 for an IDF40 down draft carb.

Since there's no manifold for IDF40 and Knucklehead that has each barrel and tube separated up to the heads' inlet (they are all 2into1 manifolds that in the end merge both barrels) I had to design one:

I call it "TheTubes" and it cost me quite a while to create the final version. It is twisted in the lower part, because I wanted to have the inner diameter of 39mm over the complete length of the tubes (of cause right after the top flange it goes from 40mm to 39mm). The inlet port of the head is 39mm as well.

I had a polyamide prototype made by 3D printing for fitment tests:

Fits as desired, exactly between both heads:

First thought for the final manifold was to have it printed in metal, AlSi10Mg, too. But ... after some inquiries I soon dropped that idea (the most expensive offer was about the price of the complete KN93 engine!). Currently I'm searching a metal casting company that is able to sand cast or precision cast that part. Next challenge to come is machining the flanges to measure.

Cheers,
Axel

#5 Raceknuckle

DCOE 40 carb. Nice quality but the velocity stacks included look a little cheapish. So I decided to make some new ones. I usually start with a CAD design of my parts and then fabricate them using mill and lathe (and what else is needed).

Just want to point out that these are not CNC made, this was all done with a normal, conventional lathe (ok, and some sand paper / polish...).

Looks good on the carb!

Cheers,

pan51

#1 Raceknuckle

Well, how to start? This story is about building a new bike, based on a fake knucklehead that I bought some years ago. It sat unused in the garage for some time and after spending some time thinking about if I should burn it or use it for something fancy I decided to start a new project with it.

The good thing about it is the fact that it has a german license stating the year built is 1947 which in turn means that higher exhaust sound levels are possible, no turn lights and mirror are needed. I decided to keep only the frame and add some new parts:

Old fender is removed and a new, light one made of aluminum is fitted as well as a Mesinger racing seat. However the Mesinger doesn't fit right, looks good from side view but seen from the top it is too wide and disturbes the frames line:

Regarding the motor I'd always liked the S&S KN93 Knucklehead so this one will make it into the bike:

It will be equipped with a Weber two-throat DCOE40. The motor will be tuned a little bit, so in preparation of the tasks to come and to decide if the S&S cam is to be used the valve lift is measured:

Most parts of the motor are getting polished, heads and connecting rods for example:

Finally, to call a spade a spade I'll name it "Raceknuckle"...

pan51