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General Category => General Discussion => Topic started by: moto on October 07, 2025, 10:58:58 AM

Title: Fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 07, 2025, 10:58:58 AM
I bought a V50 recently that came with a second set of mufflers that turned out to be the OEM V50 iii version built for 35mm exhaust pipes instead of the 32mm on the V50.

Any tips on mounting them? I can make new hangers, but am not finding 32x35mm reducing sleeves.
A simple sleeve would be just right, allowing the full length of the 32mm pipe to fit inside the muffler as intended.

I bought 32x35 aluminum pipe before thinking about the difference in the expansion coefficient compared to steel.

32mm is about 1 1/4 inch (1.260 vs. 1.25) and 35mm is 1 3/8 (1.375 vs. 1.378) but so far no luck with inch-sized sleeves that small.

I could buy Mistrals but the price is getting near $1000 with the tariff, I believe. The V50 iii ones I got look very nice.

Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: jcctx on October 07, 2025, 11:10:38 AM
Muffler shop can "swell" the pipes up size needed??
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Antietam Classic Cycle on October 07, 2025, 11:22:14 AM
Maybe a set like this and trim the ends so that they work with small I.D. pipes?
https://www.partzilla.com/product/aftermarket/2154-EMGO-80-47310
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 07, 2025, 11:37:18 AM
Maybe a set like this and trim the ends so that they work with small I.D. pipes?
https://www.partzilla.com/product/aftermarket/2154-EMGO-80-47310
That is exactly what I was thinking of :thumb: (I've just been searching Aliexpress for them for you). Alternatively, go cheapskate with some kitchen 'tin foil' (actually aluminium). You'll likely require some exhaust assembly paste to provide a decent seal.
UK link: https://www.feked.com/exhaust-reducing-bush-set-of-3.html
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: bronzestar1 on October 07, 2025, 11:53:27 AM
Another option would be to remove the head pipe, take it and the muffler to a good muffler shop, and have them "flare" the end of the header pipe to match the muffler inlet.  A little more work, but having the two ends slip fit into each other would be better than using reducers. 
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: normzone on October 07, 2025, 11:55:22 AM
32mm is about 1 1/4 inch (1.260 vs. 1.25) and 35mm is 1 3/8 (1.375 vs. 1.378)

Do some creative engineering with about twenty aluminum beer can walls ...

 :popcorn:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: PeteS on October 07, 2025, 12:12:59 PM
I have made my own out of steel and later aluminum on my lathe but I think the EMGO set is your best option.

Pete
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 07, 2025, 12:19:51 PM
I have made my own out of steel and later aluminum on my lathe but I think the EMGO set is your best option.

Pete

So how have the aluminum ones worked out? Were they simple pipes or did they have a split in them? No problems with differential expansion compared to the steel pipe and muffler? I've got a suitable pipe ready to go that will need a bit of sanding.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: PeteS on October 07, 2025, 01:10:52 PM
So how have the aluminum ones worked out? Were they simple pipes or did they have a split in them? No problems with differential expansion compared to the steel pipe and muffler? I've got a suitable pipe ready to go that will need a bit of sanding.

They lasted over twenty years but I used them on my Norton for original Dunstall Mufflers. Probably less than 20,000 miles. I used solid bar stock and bored it out and tuned the OD to fit. The steel ones were chrome plated. This done back in the ‘70s before plating costs shot into the stratosphere.
These days I am into the K.I.S.S. principle so if you can buy it then buy it.

Pete

Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: bigbikerrick on October 07, 2025, 01:47:15 PM
I have made my own ,using aluminum flashing material available at most hardware stores. Just cut it to the length you want,and wrap it around the pipe to fill the gap. I also use a smear of clear silicone RTV to further seal the joint,and it makes dis assembly easier too.
Rick
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Perazzimx14 on October 07, 2025, 05:37:03 PM
I bought a V50 recently that came with a second set of mufflers that turned out to be the OEM V50 iii version built for 35mm exhaust pipes instead of the 32mm on the V50.

Any tips on mounting them? I can make new hangers, but am not finding 32x35mm reducing sleeves.
A simple sleeve would be just right, allowing the full length of the 32mm pipe to fit inside the muffler as intended.

I bought 32x35 aluminum pipe before thinking about the difference in the expansion coefficient compared to steel.

32mm is about 1 1/4 inch (1.260 vs. 1.25) and 35mm is 1 3/8 (1.375 vs. 1.378) but so far no luck with inch-sized sleeves that small.

I could buy Mistrals but the price is getting near $1000 with the tariff, I believe. The V50 iii ones I got look very nice.

Strips of HD aluminum foil wrapped around the "male" pipe until you reach the desired diameter. I fold it slightly over the edge so it sort of rounds over making sliding the female end over it easier w/o pushing or balling up the foil.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Antietam Classic Cycle on October 07, 2025, 06:47:05 PM
Strips of HD aluminum foil wrapped around the "male" pipe until you reach the desired diameter. I fold it slightly over the edge so it sort of rounds over making sliding the female end over it easier w/o pushing or balling up the foil.

In a pinch, I've used "duct tape" (not to be confused with cloth-based duck tape) - the adhesive-backed thin aluminum tape used to seal HVAC ducting.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Bill W on October 08, 2025, 03:58:11 AM
I also have used the aluminum duct tape on some Emgo's I put on a Honda and it worked fine though it did smell for a little awhile until all the adhesive burned off.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Huzo on October 08, 2025, 06:00:49 AM
For heaven’s sake, just take the damn headers off and get them flared to suit.
Anything else is just a hotch potch heap of junk, no wonder some bikes are rough as guts.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 08, 2025, 07:09:28 AM
For heaven’s sake, just take the damn headers off and get them flared to suit.
Anything else is just a hotch potch heap of junk, no wonder some bikes are rough as guts.
You have obviously missed "the devil is in the detail". I suggest that you look at the standard header pipes on a V50 - they extend far into the silencers. So you want to butcher the standard pipes? Each to their own.  :rolleyes:

[My comments are frequently ignored on this forum, so you may do the same.  :blank:]
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 08, 2025, 09:06:30 AM
For heaven’s sake, just take the damn headers off and get them flared to suit.
Anything else is just a hotch potch heap of junk, no wonder some bikes are rough as guts.

You should read a thread before you post in it. Here is what I said my first message:

... A simple sleeve would be just right, allowing the full length of the 32mm pipe to fit inside the muffler as intended....

The pipe goes into the muffler about a foot, maintaining the velocity of the escaping gas that much further, and increasing the (quite notable) torque at lower RPM. I am being careful not to change that part of the exhaust as I switch the outer chrome shell. Your suggestion would require cutting off that foot of pipe and so butcher Guzzi's design.

Your angry use of profanity is contrary to the policies of this board and offends me and maybe others. I suggest you think before you rant.

Big shout-out here to DoubleGuzzi for his on-point comment.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: PeteS on October 08, 2025, 09:14:24 AM
I believe you are overthinking the use of an aluminum sleeve. Expansion would be minimal and I am assuming you would be using a clamp to hold it on. If the sleeve is a bit tight on the ID and won’t easily slide onto the head pipe just cut a slit in it lengthwise. If the slit is too wide when placed over the headpipe just put a dab of high temp silicone in the groove.
FWIW the after market mufflers made for Guzzis come with an opening for larger after market pipes but also include a sleeve to fit on the stock pipes.

Pete
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Perazzimx14 on October 08, 2025, 09:18:27 AM
One could also source a split muffler bushing.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 08, 2025, 09:43:54 AM
One could also source a split muffler bushing.

This is a good suggestion, but I am finding that bushings this small and thin (1.5mm) are rare on the ground. Do you know a source?
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Antietam Classic Cycle on October 08, 2025, 10:17:32 AM
This is a good suggestion, but I am finding that bushings this small and thin (1.5mm) are rare on the ground. Do you know a source?

Buy a sheet of 1/16" thick aluminum and make your own, a good set of shears will cut it. For example: https://www.mcmaster.com/8975K199-8975K379/


(https://i.ibb.co/WvLg0ZDN/aph-2-xl.jpg) (https://ibb.co/WvLg0ZDN)
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 08, 2025, 10:53:57 AM
Before I sourced a near complete stainless Keihan exhaust for my '50, I messed about with various methods, to fit very cheap 'universal' silencers. They are supplied with the 3 bush reducers but are still too large.

Then I acquired the aforementioned stainless pipes.. so that was that. ;-)

Options & Conclusions:
Cut back bush reducers are a possibility.
Heat proof duct tape, as mentioned by Charlie.
DIY 1.5mm approx. 40mm long, aluminium sheet formed into a tube, as previously mentioned.

Aluminium is softer than steel so it will 'give' before the steel will.
Exhaust Assembly Paste is easier to work with to get a seal, clean up residue and remove when attempts fail, rather than silicone, for example.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 08, 2025, 11:04:57 AM
I bought 32x35 aluminum pipe
Sorry, I forgot about that bit. D'oh! A narrow slit along its length of approx. 40mm long (Italian measurements  :huh:) and "Bob's yer uncle".  :grin:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 08, 2025, 11:07:27 AM
This is a good time to report on my current project plan, which is still not set in concrete. Constructive comments are still welcome, and all the preceding constructive comments are really appreciated. As usual asking this group for advice has changed my own ideas for the better.

The EMGO reducers Charlie first suggested are a great design. They must be 1/16 inch thick, given the description. This is 1.59mm, only a little more than the 1.5mm required. I am making similar items out of the 1.5mm-wall aluminum tube (32x35), since I already have the tube and would have to make similar modifications on the Emgos.

I originally planned to use a simple ring cut from the tube, but this does not seem to be a good design. A solid circular ring is the strongest shape to resist compression, which is why it is used in submarine hulls. So pressure exerted on it from the muffler clamp would not be transmitted to the exhaust pipe, leaving the possibility of a leak there. Simply splitting the ring would allow it to be compressed onto the exhaust pipe. The trick is to not leave too big of a gap in the split, since air could leak in at idle, causing backfires. Rick's initial suggestion of using a high temperature silicone to seal the gap is the one I'll try. (No doubt Emgo carefully sized the gap for the intended application to inch-sized pipes.)

A second consideration about the gap is that it not be so small that it disappears when things heat up. This would make it act like a solid ring so far as the ability to transmit compression to the exhaust pipe goes. This is the same consideration that goes into ring gaps on pistons. It will take only a moment of Internet consultation to make sure the gap is big enough, but I won't bore everybody with that.

The EMGO adapter has a wavy profile where the two ends come together. This no doubt leaves the appropriate gap between them. The waves help locate the two ring ends, and maybe give at least the impression of retarding any gas leak through the gap. I'm not going to try to cut a wavy profile. Instead, I figure I'll cut a simple chevron, using two straight saw cuts, to achieve both features.

Might work. 

EDIT: Thanks to DoubleGuzzi for making two more posts while I wrote this. I'll take them into account.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 08, 2025, 11:12:50 AM
Instead, I figure I'll cut a simple chevron, using two straight saw cuts, to achieve both features.
I like the V-slit idea and would help to maintain the tubular shape, though for this application I reckon a straight cut is fine.
Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 18, 2025, 08:34:54 AM
C'mon moto, we need an update on how you got on with the silencer fitting.  :whip2:
Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 18, 2025, 09:17:02 AM
32mm/1.259" & 35mm/1.378" are so close to standard 1 1/4 & 1 3/8 sizes that I would simply buy some tube, either steel or aluminum would be fine, since the temperature changes are small, and, if needed, cut a spiral slit length wise thru one side of the tube.

Cutting the slit may not be necessary.

If you can't find the correct tube sizes, then I would use bronze bearings.

McMaster.com might be a good place to start or a local metal supply vendor.
Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 18, 2025, 09:20:58 AM
McMaster Carr part number 6556N117.

$12 per foot.

I was tooooo lazy to search for 32mm x 35mm tube.

When in the mode of "I wonder if someone makes...." McMaster.com or MSC are always great places to start.

Usually, less than 5 minutes suing McMaster Carr's excellent search function will answer your question.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 18, 2025, 09:34:19 AM
For heaven’s sake, just take the damn headers off and get them flared to suit.
Anything else is just a hotch potch heap of junk, no wonder some bikes are rough as guts.

C'mon mate!

Sometimes people want quick, functional solutions, other times they want to discuss their projects with peers!

Few things in life are more fun than getting a half dozen of your friends to intellectualize a simple solution into a long discussion.

We're social animals after all.  We like pack life!!  We all do it!
Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: moto on October 18, 2025, 07:59:12 PM
C'mon moto, we need an update on how you got on with the silencer fitting.  :whip2:
Sorry to keep you in suspense, DoubleGuzzi!

I did use the 32X 35 aluminum tube I mentioned before, and cut a slit down its side after checking that the amount of expansion would be about 0.7 mm for the degree range I expected, less than the saw kerf.  It looks great -- a nice snug fit. I also fabricated one hanger out of 1/8 inch steel and then had it duplicated by a sheet metal shop when I ran out of material.

I left town before getting everything assembled, and am in Detroit. I'll post a picture after my return.

Surreal Ed doesn't read threads before posting, so deserves no response.

Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: normzone on October 19, 2025, 12:25:32 AM
In my mind I am still on my Eldo and twenty two years old, with money only for gas, oil, and beer, so these low tech solutions seem wise to me.
Title: Re: Fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 19, 2025, 11:10:14 AM

Surreal Ed doesn't read threads before posting, so deserves no response.

That is an accurate statement!   :grin:

I usually start reading at the beginning and if I think I can contribute based on questions or information in post # 3, I will chime in after reading post # 3.

Same for after I read post # 6, I will post, and again for post # 8, etc.

If the problem gets solved in post # 12, and my three posts are all redundant BS, so be it.  That's what makes forums fun, at least for me.  I like the half-baked, shoot from the hip, brainstorming format of many forums.  Especially this one.  Great fun to interact with knowledgeable, creative people.  Especially when they turn off their filters.

I hope others do the same on threads I start.

Or I might get yanked away from my computer before getting to post # 12 or the end of the thread, so I don't know the problem was solved before my half-vast wisdom is posted.

Shirley, though, it is good to know great minds think alike! 

Right?   :wink:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Huzo on October 19, 2025, 12:51:41 PM
Your angry use of profanity
Profanity…? :rolleyes:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 19, 2025, 05:33:23 PM
Profanity…? :rolleyes:
You're gonna get struck down by a thunderbolt, Huzo! I know, it's strange what upsets 'muricans yet other phrases/words are acceptable. It sucks.  :rolleyes:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 19, 2025, 06:14:38 PM
You're gonna get struck down by a thunderbolt, Huzo! I know, it's strange what upsets 'muricans yet other phrases/words are acceptable. It sucks.  :rolleyes:

Yep, it is amazing.  Humor, like all aspects of culture is very localized and time dependent!

I've told dozens of the Furrenners I've worked with that "You will never understand America until you watch the movie My Cousin Vinnie at least 3 times.

I cherish the fact that I was raised in a time and place where if anyone EVER said they were OFFENDED by something another person said, it became an open invitation for everyone who knew that person, and everyone who ever meets that person, to try to pluck at that nerve for the rest of that person's life.

Even at age 4, your grandmother would admonish you with: "Don't get upset! When the other kids pick on you, you say to them: "Sticks and stones may break my bones, but words will never hurt me!"

You rapidly learned, the other half of that game is to NEVER, EVER, EVER, EVER give your antagonist the satisfaction of knowing they got your goat!!!  If you did, you lost!

Thanks to all the gruff, nasty old timers who played that game with me when I was a kid!

It was great fun then, and still is now!

Everyone I have ever met over the age of 60 understands the rules of that game!  The yutes, not so much.

The very idea of being offended by the words of another person makes me and everyone I grew up with chuckle!

"Hey Bill, did you hear about Fred?"
"No, what?  Did he die?"
"No! He was on the internet the other day and got offended!"
"NO WAY! Hahahahahahaha!"

Ahhhhh!  The good ole days!
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Huzo on October 19, 2025, 06:28:47 PM
You're gonna get struck down by a thunderbolt, Huzo! I know, it's strange what upsets 'muricans yet other phrases/words are acceptable. It sucks.  :rolleyes:
Sure is…
I’ve gone over every word of my post and if someone can highlight where the profanity is, I’ll own it.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 19, 2025, 06:48:09 PM
Sure is…
I’ve gone over every word of my post and if someone can highlight where the profanity is, I’ll own it.

Just like beauty is ALWAYS in the eye of the beholder, being "offended" is ALWAYS a choice made by the receiver.

The receiver is responsible for their own thoughts, emotions, and interpretations.

How can it be otherwise?

I think it was Dwight Eisenhower's wife who was credited with the quote:  "No one can make you feel inferior without your consent!"

Almost exactly what Gramma taught.
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: DoubleGuzzi on October 19, 2025, 07:56:19 PM
Sure is…
I’ve gone over every word of my post and if someone can highlight where the profanity is, I’ll own it.
Goddammit, Huzo! Don't ya geddit?   :violent1::tongue:
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: SIR REAL ED on October 19, 2025, 08:51:32 PM
Goddammit, Huzo! Don't ya geddit?   :violent1::tongue:

Amen!

If you're not offended, you can't own the offense!!!
Title: Re: Help w/ fitting a 35mm muffler to a 32mm pipe
Post by: Huzo on October 19, 2025, 09:42:46 PM
Goddammit, Huzo! Don't ya geddit?   :violent1::tongue:
I do now… :embarrassed:
Now.
Back to the V50 pipes.