Dream exhaust options.

[Muddy]

By the way, when I clicked on your website, there appeared to be some sort of a virus telling me to call a number because my Apple account was violated. I could not get out of the loop.

Thanks, this is probably some sort of website bug.

[Gene1000]

Thank you, Muddy.
I appreciate your time you spent with me on this issue.
With the help you have provided, today I think I’ve made some progress. But first, I need to confirm one thing:

First, when everything is assembled and installed, the “joint” does not directly come into contact with the engine exhaust port (see photo). Instead, it is about a quarter of an inch away. Is this correct? Was this the intended design?


Second, you were right about the exhaust headers being somewhat different. The exhaust headers are different in overall size and as a result, the “joints” on both sides of the bike are different in diameter, thickness and overall size. It therefore follows that the collars on both sides of the bike are also different in size.
The collar-halves with the raised flanges are installed on the left side of the bike. The collar-halves that do not have the stepped flanges are on the right side. Otherwise, they will not fit. This is the case with my 1965 CA 77 Dream. I don’t know about other years.

[Muddy]

G'day Again Gene1000

That is great that you are making progress.

The joints do not usually tighten right up to the head. What you've shown in the last photo is normal and the intended design.

From the photos you have provided, it is now easy to see you have parts from 2 different serial number bikes. Both joints should be the same and all 4 split collars should be the same if all from the same bike. Because of this, it is possible that the headers and mufflers are also different. That may not be a problem is you are not looking for "authentic" and can get both sides to work.

The joint with the larger internal diameter should be fitted with the 2 split collars with the flanges. The joint with the smaller internal diameter should be fitted with the 2 split collars with no flanges.

Good luck and keep going.

Muddy

[Muddy]

On reflection and re-examination of your photos, I am concerned about the large internal diameter of the larger joint. The internal diameter looks way too big. Anyway see how you go.

[Gene1000]

Thanks for all of your guidance, Muddy. Very much appreciated.

I had no idea that the bike has parts from two different serial number bikes. Now the schematics make sense.

I bought the bike from a police officer in January 1966 and as such it was literally brand new. Minimal mileage. It is very strange that components of the exhaust system are from different bikes. I never made any changes in all the years that I owned it and the police officer that I bought it from only owned it for a few months. Perhaps an exhaust header was damaged and the previous owner ordered an incorrect header that had to be retrofitted with parts made specifically for it.

I’ve been restoring this.bike on and off for three years. Attached is a current photo. The only things it needs are new exhaust pipes. Finding originals is next to impossible.

[Muddy]

Hey Gene1000

Congratulations - nice looking bike.

I thought you might like some very interesting and relevant information from Mr. Honda, Bill Silver, on this topic. I noticed Bill Silver says, "These changes necessitated some new mounting hardware for the Dreams, on the left side only."

This is an excerpt:

Exhaust Pipes – Mufflers

"Silencers of the Lambs," a Honda "Techknuckle Page" by Bill Silver.

With few exceptions, standard-equipment Honda motorcycles are very quiet ("Quiet as a Lamb"), during normal operation. Little 50cc “Cub” versions are almost electric, in comparison to the two-stroke competition of the day.

… the Dream and Super Hawk (C/CA & CB72/77), often had their mufflers left intact, although there was the temptation of removing the "diffusers"(baffles), which were held in with a single 6mm bolt. Most Super Hawks and Dreams appear to have used the same mufflers from beginning to end, but that is hardly the case. As with almost all Honda models, there were modifications and product improvements, throughout the production run, on all of them; and it is important to know this when restoring your bike.

The original chromed steel Dream mufflers, from '61-62, used a "sleeve-type" sealing gasket between the header pipe and muffler, which had a lip securing it to the sharp edge of the inlet side. The engineering upgrade for this design was the O-ring-type gasket, commonly seen on most "two-piece" (separate header pipes) mufflers. These mufflers were usually chromed-steel, on both models.

In the period of 1962-63, however, many Dreams could be found with stainless steel mufflers, which carried their own unique part number. These were substantially lighter than the chrome-steel versions and were generally corrosion-proof. The appearance was a bit duller than chrome, but a good polishing job would narrow the difference to next-to-nothing. Stainless versions gave way to chrome steel again, from around 1963-4 onwards, and they suffered the inevitable rust out.
In their quest to maintain peace and quiet, Honda decided to create single-piece (aka the "1-piece") muffler systems, incorporating the header pipe into the muffler, as a unit. The forward muffler flanges were modified to make an outward flare and the inside diameter was reduced to a snug fit. A collar was welded to the header pipe, adjacent to the muffler connection and malleable steel "donut" was swaged over the connection of the two pieces. Originally, the header flange (exhaust pipe joint) was slipped over the outlet end of the header pipe, the hole being slightly larger diameter than the pipe. Two straight-sided (half circle) collars were used to retain the header pipe flange into the cylinder head.

With the new "one-piece" system, the pipe joints were too small to fit over the header pipe inlet flange, so new joints were cast, with a larger inside diameter hole, to facilitate slipping over the header flange. This meant that the collars had to have a 90-degree flare at one end to make up the difference in size. Originally, both the Dream and Super Hawk used a -259- pipe joint and collar. With the changes, the pipe joints acquired a –268-000 part number (apparently Super Hawks got the change first) and then used the -273- (Scrambler) 90 degree, flared split collars to secure the header pipe. These changes necessitated some new mounting hardware for the Dreams, on the left side only. The exhaust studs usually have to be changed for the next longer length, as well, when converting from 2-piece to 1-piece systems on either model.

The part numbers changed, of course, to an 18300 and 18400 prefix, for the one-piece units vs. the 18130 and 18330 (right and left) for the two-piece designs. Early one-piece CA/CB designs used the original continuous-curved shaped headers, attached to the new mufflers (18300/18400-272-000). Inexplicably, Honda began to build Dream and Super Hawk replacement header pipes with a "double-bend" shape, (crude example = __7 vs __) shapes, which is the best I can do here) which was often incompatible with the bike's chassis and often fouled the starter motor, because of the poorly-formed shape.

The -259- two piece Dream mufflers were given a -272 (CIIIA72) product code designation, when sold as the one-piece part. EPA/DOT-stamped Dream and Benly SS (and other) two-piece mufflers usually carry a -017-suffix code. Mysteriously, while the last replacement mufflers for Super Hawks were all one-piece versions, Honda discontinued the -272- Dream units and went back to supplying 2-piece mufflers (usually the -017 version), until they were discontinued altogether.
Here are some sequences of the part number changes for all 250-305 Dreams:
RT. 18310 (LT. 18330)-259-020/-027/-030/-315/-017(EPA) 2-piece Dream muffler
RT. 18300 (LT. 18400)-272-000 1-piece Dream muffler

Enjoy your Dream!

Regards

Muddy