Hey guys, I recently bought a 2018 S40 and have followed this thread to rebuild and rejet my carb, install a raptor petcock and raise my seat. So here I am at the last piece of the Trifecta, doing the Dyna slip on. I bought the 65747-94 model which requires the least amount of work. I followed Serowbot's guide to install using tin can gasket and T bolt clamp but I cannot get this thing to seat fully. It stops with about a quarter inch gap left. I've attached photos. Any help us greatly appreciated. This is my first post so I hope I am following the proper procedure. - Clay

Did yours sit flush with the end of the downpipe? Did you need to hammer it on? I tried the tin can gasket but am having a leak. I followed the guide and cut slits down the flange to help it on but it looks like it tapers inside and gets caught at the very end of the downpipe  :'(

I started doing the tin can gasket, but didn't care for it. I ended up just using some exhaust sealant goop from a tube from auto zone. Then I put an exhaust clamp on it.

EVIL ENERGY 1.75" Heavy Duty U Bolt Exhaust Clamp, 1 3/4 Inch Stainless Steel U Muffler Clamps, Saddle Style, 2PCS

Needles wrote on 10/14/25 at 05:55:25:


What silencer are you using there ?   The reason I ask is that it does not look like it lines up with the pipe.

"What silencer are you using there ?   The reason I ask is that it does not look like it lines up with the pipe." [Blod]

It's an HD Dyna take-off. The OEM setup has a slight, maybe 5-10 degree, turn out, to help it clear the brake rod. It's more like the angle of the shot.

The exhaust (downpipe) is stepped. I just cut off the step, maybe 1/4".
Slide the muffler on, check to see all the slots are sealed. If not you'll have to shorten the muffler inlet by maybe 1/4" and recheck.
Wrap a 1" strip of heavy duty alum foil slathered with J-B Weld red silicone around the exhaust.. Wear gloves, very messy. Slide on the muffler noting where the attachment bolt meets the bike. I used a lag bolt. Slide the muffler onto the exhaust, rotating as needed.
Slide the muffler clamp over the joint. Start tightening all bolts, adjusting as needed until it starts to look right. Step back 6 feet and look again, adjust as needed. tighten everything.
This is too messy to do more than once, so 'think' and get it right first.
Mine looked good and didn't leak. Good luck !
Cheers!  
ps: reducer is too tight so didn't use. Alum foil strip and JB goop works fine.
pps: make sure you slide the muffler all the way to the ring
ppps: you really need 3 hands for this! Don't forget the 'never-seez' on the exhaust bolts.
pppps: you did remove the right-side case to check the cam chain tensioner extension first, didn't you?
ppppps: This is one of the reasons I felt giddy when the buyer rode away!