Britbike forum

Classic British SparesKlempf British PartsBaxter CycleThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supplyJob Cycle

Upgrade your membership to Premium Membership or Gold Membership or even Benefactor


New Sponsor post
10% Off Girling at The Bonneville Shop 2/3-2/9/23
by The Bonneville Shop - 02/03/23 6:14 pm
New FAQ post
News & Announcements
Premium members! 🌟
by Morgan aka admin - 02/04/23 2:40 pm
Buy BritBike staff a coffee ☕️ or pint 🍺
by Morgan aka admin - 01/15/23 9:29 am
Benefactor ✅
by Morgan aka admin - 01/08/23 8:38 pm
How to guides - Technical articles
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Member Spotlight
Denis J
Denis J
Sacramento, CA
Posts: 485
Joined: November 2012
Top Posters(30 Days)
Lannis 84
DavidP 83
Top Likes Received (30 Days)
Kev. 34
DavidP 27
Newest Members
Uneasy Rider, Mally, Daveed, 70Triumph, Knight57Corv
12,392 Registered Users
Forum Statistics
Forums35
Topics76,551
Posts784,409
Members12,392
Most Online204
Jul 10th, 2022
Random Gallery photo
Photo posting tutorial

Previous Thread
Next Thread
Print Thread
#895927 11/20/22 5:37 am
Joined: Jan 2014
Posts: 4,196
Likes: 97
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Jan 2014
Posts: 4,196
Likes: 97
Hello; I made open pipes but with trumpet/horn tips that measure 9 inches long each one and start at 1 1/2 ID to 2 3/16 max ID at the ends.
Motor is 750 Triumph and I am obtaining harsh strident sound; nothing at all like 650 s and 500 with straight pipes and deeper notes.
I am trying to restrict the pipes at minimum; however, minimum seems the infamous big washer...that no one favor but seeing some muffler s end like Supertrapp etc I see that they sell and have in some models kind of big washers with the main hole and then smaller ones all around. They suggest to check to use one or more depending the situation.
I do not know how much distance between them; also may be still not working regarding back pressure etc
Here is no any dynamometer to check some details.

All other kind of things that I see are too restrictive and may be difficult to put inside those cones?

Thanks

Check out some eBay stuff
reverb #895951 11/20/22 1:40 pm
Joined: Aug 2001
Posts: 1,873
Likes: 51
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 1,873
Likes: 51
How about inserting a typical baffle in the pipe before mounting the megaphone? What diameter is the exhaust pipe?
https://i.ebayimg.com/images/g/cugAAOSw98RdGnYP/s-l1600.jpg


Al Eckstadt
reverb #895970 11/20/22 5:34 pm
Joined: Jan 2014
Posts: 4,196
Likes: 97
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Jan 2014
Posts: 4,196
Likes: 97
The pipes are 1 1/2 and I welded the cones; then sent to chrome.
I do not know about what is good and what is bad regarding exhaust restrictions but I thought that those baffles as you show in those photos could be more restrictive than a washer or 3 at certain distances between.

reverb #895977 11/20/22 6:37 pm
Joined: Aug 2001
Posts: 1,873
Likes: 51
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 1,873
Likes: 51
OK.
To avoid the "infamous" flat washer you could try bolting in other shapes of metal. It may be that you just need to break up the pulsations somewhat rather than restrict them. Try a 12" or so length of perforated metal tubing, flattened gradually with the inside end pinched closed. Or the perf metal could be cut and rolled into a cone shape, tack welded and pinched shut at the end.
The total square area of holes in the perf metal should at least equal the area of the exhaust pipe outlet, causing almost no restriction but breaking up the sharp blast from each pulse. This would be almost unnoticeable, and would not involve welding on your chrome pipes.
Al


Al Eckstadt
reverb #895981 11/20/22 6:59 pm
Joined: Jan 2014
Posts: 4,196
Likes: 97
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Jan 2014
Posts: 4,196
Likes: 97
Sounds good. If I understood right, do you mean to use perforated metal sheet or do the holes like those mufflers but I do not get it how I fix inside; if do not weld it. I can send it over to chrome again but I was thinking to make holes for the possible bolts, before the chroming.
-What would be the distance from the internal diameter? about 3/8?
-

reverb #895996 11/20/22 8:55 pm
Joined: Aug 2001
Posts: 1,873
Likes: 51
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 1,873
Likes: 51
You said you do not want the restriction of the washer. I was thinking of a tube of perf metal that would fit close to snug in the muffler - then notch it so it will roll into a cone shape, and have the tip inside closed - so all the exhaust must pass thru the perf metal. The cone would be inside your exhaust pipe, almost unnoticeable. I suppose you could roll a larger cone and attach it inside your megaphone but I don't think that would look good.
The square area of all the holes would have to equal or exceed the square area of the exhaust pipe diameter, otherwise there would be a restriction.


Al Eckstadt
reverb #896056 11/21/22 5:14 pm
Joined: Jan 2014
Posts: 4,196
Likes: 97
reverb Offline OP
Britbike forum member
OP Offline
Britbike forum member
Joined: Jan 2014
Posts: 4,196
Likes: 97
...may be closing the rear part of that mesh cone? so the gases go between the cone and the perforated tube (conic) not directly as open in both sides.

reverb #896064 11/21/22 6:41 pm
Joined: Aug 2001
Posts: 1,873
Likes: 51
Britbike forum member
Offline
Britbike forum member
Joined: Aug 2001
Posts: 1,873
Likes: 51
That's what I mean - except I'm picturing the narrow closed end is extending into the pipe (toward the front of cycle). Where it would attach - at the end of the straight pipe - it would barely be visible at all.


Al Eckstadt
reverb #901595 01/30/23 1:23 am
Joined: Nov 2011
Posts: 332
Likes: 10
Britbike forum member
Offline
Britbike forum member
Joined: Nov 2011
Posts: 332
Likes: 10


Moderated by  GrandPaul 

Link Copied to Clipboard
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2023 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5