Topic: Muffler and Exhaust diameter gap, Best way to make a tight fit?

[Ericcb750]

Hey guys, I have a new Core Engineering Quite Core muffler that is 2.25" in dia. I also picked up a 78 F Model 4-1 header that has a 2 1/8" Diamter opening. So there is a difference of 1/8 inch between the two, Definitely too much to just clamp it down. I'm wondering if anyone has run into an issue like this before and what is the best way to get a nice tight fit? I was thinking of brining it to a muffler shop around here and see if they can make a sleeve or something to make up that 1/8" . I do not want to Weld the muffler to the header and I do have some heavy duty clamps for it. Would a few layers of muffler tape do the trick ? Any suggestions would be great, or if anyone has dealt with this situation and has advice, I would appreciate it. Thanks guys. Take it easy.

[flybox1]

Search 2.5" muffler reducer

[Maurice]

I've used something like this.

Roll it around the pipe and cut it in a zig/zag fashion at the joint. Acts like the piston gaps. Trick is to cut the exact length, best to cut more then trim than the other way around.

BTW the stock F headers do have a cylindrical gasket there, maybe that's all you need? 13 below, DSS still has(d) them:

[AbbyRider]

I had the exact same sizing issue. Needed to make up that 1/8". I bought this red tape that is made for the application. It seals up when it gets hot. I clamped it right at where I put the tape. No leaks yet. Seems pretty solid. And way cleaner than a reducer (which I couldn't really find anyways).

[eigenvector]

Cut up some tall boy beer cans and use them for gasket material?

If you don't want to go that route - I have no doubt a muffler shop would flare it for you for a trivial cost.

Edit:  Maurice mentioned it, isn't that what the gasket is for?

[Don R]

I'd sleeve it with muffler pipe, slice it so it can sieze between both the collector and the muffler. Unless you're putting on an awesome hanger. With due respect, I'd leave the tape  out of it, it's just too much gap.
 I made mufflers for the F0 and F1 header for a while, I cut the muffler pipe in 2 places and used a T bolt clamp. You can roll the T Bolt under and back where it isn't seen.
 I'm building a bender, I'll have to try my hand at header tubing.

[Ericcb750]

Hey Guys, Thank you all for your help. I checked out the Gasket on David SIlver Spares, It looks like exactly what I'm looking for but I e-mailed them to see what the thickness is. Not sure if just one will make it a nice tight fit or if I may need 2 ?? I don't want them to flare the Header pipe , it's pretty beefy and it's an original so I don't want to mess it up... I appreciate all your help/advice on this. I'm glad others have had experience with this same thing. I currently have the Stock 4-4 pipes on there and Can't wait to hear the new exhaust on it. 

Will the heavy duty clamps be enough to squeeze the muffler onto the collector once I get the space filled in? I don't want to have to get the muffler welded on if I can help it. Thanks guys, take it easy.

[CB750R]

I'm keen to see how this looks! Been eyeballing  those mufflers.
 look up walker exhaust makes a lot of adapters and reducers.

http://www.walkerexhaust.com/assets/downloads/english/Walker_Hardware_Accessories.pdf

[flybox1]

Hey Guys, Thank you all for your help. I checked out the Gasket on David SIlver Spares, It looks like exactly what I'm looking for but I e-mailed them to see what the thickness is. Not sure if just one will make it a nice tight fit or if I may need 2 ?? I don't want them to flare the Header pipe , it's pretty beefy and it's an original so I don't want to mess it up... I appreciate all your help/advice on this. I'm glad others have had experience with this same thing. I currently have the Stock 4-4 pipes on there and Can't wait to hear the new exhaust on it. 

Will the heavy duty clamps be enough to squeeze the muffler onto the collector once I get the space filled in? I don't want to have to get the muffler welded on if I can help it. Thanks guys, take it easy.

@Ericcb750 - some very thin sheet alu will be a good start.  1" x 20" and wrap your header.    Use a hose clamp one the engine side of the wrap to hold it in place as you slide the header on.  kinda like a piston ring clamp    if its too thick, cut it back 4" and try again.
The heavy duty clamps are great, and look nice, but you need a tight fit to begin with as the compression is minimal.

@CB750R - it took me a bit to get the jetting right, but i love how it looks and sounds.

[Ericcb750]

Hey Flybox and 750R thank you for your help. I ended up talking with Mark at David Silver Spares to get the dimensions "thickness" of the gaskets for the "F" model header to muffler space. He was nice enough to measure them for me and gave me the dimensions... 3mm thickness = 1/8 inch!!! perfect! so I did order up a gasket (along with a few other things I probably don't need -  ... As soon as I get home from my trip they will have arrived and I will make and post a video of the entire exhaust system as well as how it sounds....Extremely excited to hear how it roars after hearing Flybox's video on you tube.... All the guys on here have been excellent at helping me with my first ever CB750...my 2nd ever bike and I could not be happier with it. A few nutty carb tuning sessions and it's running very well. I'll PM you guys for your e-mail address's if I'm having trouble posting the video (flybox I think I have yours already). Thanks again guys, should be hooking it up this weekend and hearing it. I appreciate the help