• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

CB350 K4 Mufflers....bit the bullet.

GaryJames

GaryJames

Veteran Member
Joined
Jul 7, 2022
Total Posts
311
Total likes
110
Location
Auckland, New Zealand
After contemplating my exhaust headers unequal length for some time I have come to the conclusion the PO ( pre 1981 ) must have cut the right hand side down to fit some after market mufflers that were already in bad shape when I bought the bike as a commuter. I never noticed the different lengths at the time. I frequently patched the holes through the next 7 years of daily riding..... When I pulled the bike from storage August 2022 to begin the restoration the first thing into the bin was the mufflers that were just holding together.

So I have gone ahead and purchased the CB350 clubman ones from Common Motors. At least these ones look okay and they seem to have removabe baffles.
Internet searches ( Amazon, Ebay, Ali Express, Thailand and elsewhere) show a heap of universal mufflers for CB350, cheaper than from Common Motors, but the risk is the shapes and sizes will look odd, or will take too much fettling to fit.

Having got to this stage I wish I had thought more about the headers being of unequal length before getting the pair of headers re-chromed. I am going to have to get an extension pipe welded on the right hand one to match the left hand header pipe length then get it re-chromed again.. sigh... it is only money after all.

The rest of the bike is 99% finished and it is engine start time.
If I do it without mufflers I will be living in a tent on the back lawn.


cheers

Gary
Auckland
 
Would there be interference anywhere if you cut the longer pipe to match the shorter one? That would let you skip the welding and rechroming, and get you on the road.
 
fxray said:
Would there be interference anywhere if you cut the longer pipe to match the shorter one? That would let you skip the welding and rechroming, and get you on the road.
Click to expand...

If it wasn't a huge difference, I'd be inclined to do that and adjust the muffler brackets accordingly as a simpler (and less costly) solution.
 
The new Mufflers have arrived.
I purchased Clubman type for CB350 from Common Motors.

First one is one the bike.
IMG_2230.jpg

To my eye it looks far too short. This is the side with the correct length Header Pipe. The OEM Honda mufflers end way past the rear wheel spindle.
However since I have to do something anyway to the other side to lengthen the short header pipe I might get two extension pieces made in stainless steel ( which I will polish to chrome like ) for both sides.
I had to do a couple of angle bends on the hanger strap to miss the swing arm and arrive at the frame bracket.
I am a bit miffed about it as Common Motors don't give any dimensions on their web site.. I should have asked for them.

What do the members think?

Not so cheers

Gary
Auckland
 
Sorry, meant to add the Oil purifier cover is off waiting for 2 x O rings.
They did not come with the supposedly complete gasket set.
Gary
 
I prefer the stock length mufflers;just used to the exhaust going all the way back.
I find that the longer mufflers improve low-mid-range power compared to shorter length which seem best for high rpm power,imo.

The stock mufflers are difficult to find(HM344 stamped into the cases)although David Silver Spares does sell the reproduction mufflers which many have enjoyed owning.
 
To me, as one who appreciates authenticity, I think that given all the work you appear to have done on the bike, these shorter pipes detract from the overall restoration. I often say this is an 'each to their own' thing, but if the bike were mine, I'd be buying the David Silver reproductions and sell what's on there.

As you say: 'it is only money after all.';)
 
For what it's worth I agree with Hondaholic - when all's said and done it is entirely up to the individual but my personal preference is to keep these bikes as original as is practically possible.

My '72/73 CB175 had the original (but pitted) HM338 exhausts fitted when I bought her and it grieved me to remove them and replace with OEM "look a like" equivalents (from David Silver) but for the sake of a rust free appearance I had no choice. Non-standard exhausts were much cheaper but I couldn't bring myself to spoil the look of the bike. I still have the HM338 exhausts gathering dust - just can't bring myself to move them on :sad:.
 
It's unfortunate that most of these bikes' exhaust is the single-most visible appearance item while also being the part most susceptible to the decades of rust and deterioration. Unless I'm going custom/modified in some way, I prefer the look of stock exhaust myself but unfortunately most factory exhausts are the worst condition part on most of these bikes as bought simply due to the age and corrosive effects of exhaust on metal and the amount of time sitting idle in between. It makes for an expensive and difficult decision that affects the entire look of the bike unless you get lucky and find good used parts.
 
michaelgj said:
. . . I still have the HM338 exhausts gathering dust - just can't bring myself to move them on :sad:.
Click to expand...

Michael, if the need arises, check Castle Chroming in Dudley: https://castlechrome.co.uk/

They fixed a pitted silencer of mine by cutting out and replacing a section. Job came out better than surgery on Katie Price and after plating one wouldn't know the difference.(y)
 
Hondaholic said:
Michael, if the need arises, check Castle Chroming in Dudley: https://castlechrome.co.uk/

They fixed a pitted silencer of mine by cutting out and replacing a section. Job came out better than surgery on Katie Price and after plating one wouldn't know the difference.(y)
Click to expand...

Thanks for that. I am planning to re-chrome my handlebars and a few other bits and pieces so will certainly ask the question about the original exhausts - I just assumed these were a "no no" due to the carbon etc. I did email Walkinshaw's at Hinckley asking for a ball park quote but they don't seem very forthcoming so not sure if they are still in business - I have heard good reports about Castle Chroming so will certainly try them instead.

Cheers
 
Personally I think they look OK on the bike. I am one that likes things to restore to authentic, but sometimes parts can not be found, or are so crazy expensive I opt for a decent looking alternative. I was not aware that anyone made a reproduction. I just looked at David Silver spares and saw them. Probably $500 for the pair after you tack on tax and shipping. Thats not a bad price actually for a set. I see reproductions for other bikes go for over $1000.

Again, It all really depends what your project goals are and what your budget is.

You sound like you have a similar problem that I do, and I will look at it over and over and it just does not seem right. Just to let you know, they do look nice, so don't let that bother you. If your project goal was to make it completely authentic, (or to make a show class or world class bike) then buy the reproduction ones Otherise enjoy it knowing they look nice as compared to a bike nice bike with original ones with holes, rust, or repainted black or something.

Your bike in the picture looks Great BTW!!
 
michaelgj said:
. . .will certainly ask the question about the original exhausts - I just assumed these were a "no no" due to the carbon etc. . .
Click to expand...

They, like most other platers, will insist that exhausts are cleaned/flushed with barbeque cleaner or similar.(y)
 
Thanks to all for advice and comments…
I will cogitate on it for a bit.
first thing if I go the extension way is to find some SS pipe of suitable size.
at this stage my idea is to add say 6” of extension between Header and Muffler joint.

Cheers
Gary
 
It's the sound that would bother me, I expect those Dunstall style exhausts ( can't call them 'silencers' ) will be unpleasantly loud.
 
I’m not sure what your muffler support bracket setup is, but a much simpler setup is to run the chrome hanger strap to the backside of the passenger footpeg mount and use that bolt (use a longer bolt if necessary) to secure it. You may have to drill another hole in the muffler strap to line up with the footpeg bolt and possibly shorten the strap. My hanger strap is black, but I think you can see it in this photo.

BTW, it’s too late now, but pretty much all the chrome mufflers sold by Common Motor are made by Emgo, and can be found cheaper elsewhere. You can also access the Emgo catalog on line and they provide all the measurements. The mufflers in my photo are also made by Emgo, they are replica Dunstall reverse cone mufflers, and are about the closest thing to looking like the originals that I found in cheaper aftermarket mufflers.

A460BBD4-6FC8-44D9-BB78-C7CC0A8C74E9.jpg
 
These are the repro mufflers I had made in the UK. I just didn't like the look of the David Silver ones. Horridly wide seams and some dodgy form of welding on those seams. So I went to the guy who owns the tooling and commissioned my own set to be made to Honda spec. seam widths and continuously TIG welding to the seams. Like the D.S. ones they have HM344 style baffling ( as fited to K4) models and clamp directly onto the headers (i.e. no insulator ring). The good thing is that I had another three sets made and you couldn't tell them apart in terms of quality and finish.

Mufflers.jpg
 
Hi .... Actually cheaper than David Silver £105 + 20% VAT tax each but that was early lasy year. He is just quoting me for another six sets.

The thing is although he's a great guy D.S. is a businessman and really screws his suppliers hard on price .. I know this because I have also dealt with the guy who makes his seat covers and the same there. So they have to make repro. parts down to a price and I suspect that with the mufflers the seams have to be wide to allow some kind of continuous kind of spot welding ...which IMHO looks awful.
 
ashimotoK0 said:
Hi .... Actually cheaper than David Silver £105 + 20% VAT tax each but that was early lasy year. He is just quoting me for another six sets.

The thing is although he's a great guy D.S. is a businessman and really screws his suppliers hard on price .. I know this because I have also dealt with the guy who makes his seat covers and the same there. So they have to make repro. parts down to a price and I suspect that with the mufflers the seams have to be wide to allow some kind of continuous kind of spot welding ...which IMHO looks awful.
Click to expand...

I understand what you mean. That is a great price for that level of quality, too bad shipping to the US would make it so much more in the end.
 
ashimotoK0 said:
. . . So I went to the guy who owns the tooling and commissioned my own set to be made to Honda spec. seam widths and continuously TIG welding to the seams. Like the D.S. ones they have HM344 style baffling ( as fited to K4) models and clamp directly onto the headers (i.e. no insulator ring). The good thing is that I had another three sets made and you couldn't tell them apart in terms of quality and finish.

View attachment 20180
Click to expand...
Those are beautiful. I have never heard of someone doing what you describe here. If you could do that for CL350 high pipes, I think there would be a good market!

One of the things that boggle my mind about a visit to the Barber Museum is that every bike on display seems to have perfect, original exhaust systems.
 
I have decided that the short clubman style mufflers don’t do it for me.
so I have listed them for sale, as new, on local NZ web site to recoup some of the expense.
I have placed a back order with David Silver for the repro type he sells.
I also tried contacting his manufacturer direct but no response from them to my email enquiry
meantime I have found longer set of aftermarket mufflers on eBay.
https://www.ebay.com/itm/3047460758...YfjTW+GCEQIaq8709srfYchZ/SbQ|tkp:BFBMlJGdq9Nh
these measure just over 700mm total length so okay there.
closeup on the welding shows bad welding but being made in Thailand I don’t suppose any standards are adhered to!

might get them so I can at least start the bike. since DS can give me no shipping date although they advise they are in weekly contact with the manufacturer.

Dissed Gary
Auckland
NZ
 
Those look pretty good, but don’t appear to have any clamping slots on the small end.
 
Yep, I noticed that but careful hacksawing should remedy.
The slot needs to be about 1/8 of an inch wide so two cuts close together at hacksaw blade thickness will do. Then wiggle the centre waste until it breaks and clean up the throat with a small file.
I have done this before when modifying car exhausts in my go-faster days..!
Gary
 
If you cut them make sure to paint the cuts with a good SILVER High Temp Paint or it will be a Rust Starting point.
 
Good spotting Ashimoto, however the end on pictures show no slots so we will wait and see what arrives !!

Yendor , yes of course to painting the bare metal with Hi temp silver....

Gary
 
GaryJames said:
Good spotting Ashimoto, however the end on pictures show no slots so we will wait and see what arrives !!.

Gary
Click to expand...

Yep, there are none in the photo I looked at.

D65616C7-6B01-4B9C-A6FD-086B56A52E77.jpg

I bought some mufflers with no slots or clamps a couple years ago. It was a chore to find some 1-5/8” chrome exhaust clamps, and I had to cut slots in the mufflers, too.

00C3DAEA-744B-425E-B7FE-26DB2086E8FE.jpeg
 
Just before I was about to buy the longer made in Thailand mufflers David Silver advised they had shipped my back order.
So, he now has a few CB350 Honda Pattern left and right mufflers back in stock.

I am glad I cogitated over but the others now.!

Cheers

Gary

I checked his web site and this morning and it shows he has 20 sets of left and right.
 
Last edited:
5 days from UK to Auckland NZ, not too bad !!
Trial fitted the right hand side to measure up for the hanger plate.
IMG_2267.jpg

Excuse the cardboard template.
This looks much better...
I will need to get the left hand Header pipe extended by 4" as the PO cut it to fit some other after market mufflers.
I will then get it re chromed..

This is the fish tail on my 1946 Ariel VB600
IMG_2268.jpg

Which one looks better?

Now a confession.
It would seem I suffered from the late night ( after a few beers ) buying spree inadvertently of course.
I thought I had just left my shopping cart with the Thailand mufflers to actually decide later.
I must have pushed buy as they are on their way...
Oh well, a bloke can't have too many mufflers now can he !!!

Cheers

Gary
 
Yes indeed. The buy button does see more action during a session! Few regrets though.
 
GaryJames said:
5 days from UK to Auckland NZ, not too bad !!
Trial fitted the right hand side to measure up for the hanger plate.
Click to expand...

Those DSS mufflers do look good.

I have an observation that has nothing to do with mufflers - why does your later CB350 have the earlier kickstart lever on it? Why don't you have the one that pivots at the bottom and folds out of the way so much better?

GaryJames said:
This is the fish tail on my 1946 Ariel VB600
Click to expand...

And I had no idea you had a 1946 Ariel... wow, very nice. I've never been a big fish tail fan though.
 
Hadn’t thought about the KS lever AD. It came fitted with the bike when I bought it in 1981.
The peg folds in at the top and didn’t cause me any worry back in the day that I can recall.
since you raise the question I will look around for the correct one!

I built the VB up from literally a pile of rusty parts over a couple of years. I had never seen it together so it was in part a detective story with a steep learning curve.

cheers
Gary
 
GaryJames said:
I built the VB up from literally a pile of rusty parts over a couple of years. I had never seen it together so it was in part a detective story with a steep learning curve.
Click to expand...

Well, I think you passed the course with flying colors, it looks fabulous.
 
AD, checking the exploded diagrams on cmsnl the CB350 K4 Australian export model lists both types of kick starter.
I use the Australian K4 model as they don’t list a NZ one.

If the top knuckle item was cheaper back in the day then that is what a NZ Honda importer would have specified.
importing cars machinery motorcycles and the like was strictly controlled by the Govt. based on imported value.

Don’t like the price to buy one from cmsnl though!

Gary
 
I'm not sure that Honda would have offered both with an option of one or the other, they typically made changes as improvements came along and I suspect it might have been a mid-year improvement. The later CB/CL450 used the same kickstart lever so that widens the field of models you can search for on eBay to find one affordable.
 
I got my DSS mufflers in.

Pros: they sound so much better than Emgos. Very nice.

Con: The didn’t exactly fit right. Like they are a bit short. With the rear bracket aligned, there was only about 1.5” on the header. Which left a bit of the slots exposed.

I widened them enough to fit one of those spacer and it covered the gaps. Feels secure. Doesn’t seem to leak.

OP, was it different for you? Mine is a K1.


‘69 CB350
‘68 CB450K0
 
It was a bit chilly out. But I took it for a spin.

Wow. I could actually hear my engine at road speed. First for me. And I didn’t feel so conspicuous going through the neighborhood. Very nice.

I bet I can put my stock jets back in though.


‘69 CB350
‘68 CB450K0
 
Teebo,
my trail fit seems to fit okay, the muffler goes onto the header by about 1.75 inches. This depth is enough so the slots cover all the header pipe with no gaps.
mind you I had to make my own hangers, triangular shape with exactly 9 cm between each hole centre.
The muffler input pipe is quite a close fit so no need for any sleeve gasket as discussed elsewhere on VHT.
I plan to use some hi temp red silicon from Permatex, but there are plenty of other brands about.
I have used it before on my Fraser Clubman 4 into 1 exhaust system with good success.
Cheers
Gary
 
Header came back from the Chromers in a week which is good.
So offered up to the engine and fitted the off side ( left ) DSS muffler and its new bracket all fits as advertised.

Now since the Thailand ones arrived ( the ones I inadvertently purchased one night after a few beers !) I decided to fit dry fit those as well.

The header pipe tail ends are now both at what I think is the correct length since the DSS items fit pretty good with the Honda look alike brackets I made.
However the Thailand ones despite them stating they will fit a CB250/350/400 they don't go on far enough so I modified a couple of straps to install and mounted them using only one muffler attachment stud.
The end of the muffler extends to about the right distance so I am happy with that. I might make a another bracket to suit theses mufflers that has the normal three point attachment.
Also these came without any relief slots in the input end to allow a clamp to tighten on to the header pipe. But the joint is tight and I will use some hi temp silicon to seal.
There is plenty of header/muffler overlap at the joint.
If I don't put slots in them and use a clamp I will need the three point bracket to firm everything up.
They don't look too bad except they have stamped a logo on the outside which is so so.
Some pics:

IMG_2295.jpg IMG_2294.jpg IMG_2296.jpg IMG_2297.jpg

I think they are sort of reverse cone type .

For those sports car petrol heads here I put up a post in the misc section with some Pics of my Fraser Clubman with the bonnet off and some comments.

cheers
Gary
Auckland
 
Last edited by a moderator:
I will of course report back on the sound after I get it started and running okay.
meantime I am having second thoughts on the Thailand Mufflers input pipe.
Since I only have one rear mounting bolt on the Muffler in play presently I think I will cut some slots and put a couple of clamps on.
I am worried that with just one good anchor point toward the rear is not enough and the front pipe over pipe joint will quickly break any silicone seal I apply. Even though it is a relatively tight coupling there is some movement side to side when pressure is applied by hand.
Gary
 
You must log in or register to reply here.
Back
Top Bottom