Will be making my own exhausts

The exhausts on my new (to me) VZ800 are obnoxiously loud and I don't relish the conversations with the neighbours at 5am when I set off for work so my original plan was to get a cheap std exhaust 2nd hand and mod it to try to find that sweet spot between std and obnoxious. My revised plan though is to make my own. I plan to use the standard downpipes which appear to be stainless and make a set that will attach to these whilst still allowing the std cans to go on should the MOT require it or a future owner desire it. The first thing that surprised me is the std downpipes are just 1 1/8" diameter and all the beefy looking aspect is just smoke and mirrors from a heat shield. Secondly the balance pipe will have to be cut off and the holes welded up. The balance pipe runs from one downpipe to the other silencer rather than the other downpipe meaning it's removal is the easiest solution to my design. Thirdly the end plate for the std cans is just mild steel and rusty as hell. That's cheap of Suzuki to use mild in such an area.



The plan is to use a pair of these....



....which have a 2" bore, 16" body and are straight through, then weld a reducer down to 31.75 to one end which should nicely overlap and clamp to the downpipes. Shame they're only T304 stainless and not T316 marine grade but exhaust wrap is always an option if it rusts. Being a cruiser it already weighs the best part of a quarter tonne so I don't need to make an exhaust from paper thin titanium. Good old weldable stainless will do nicely. Into these I can then fit a baffle...



...at MOT time. If I get it right it will hit that sweet spot unbaffled and will be a simple job at MOT time. If I get it wrong I still have the option to slip the std silencers on albeit that will be somewhat more work than slotting baffles in. Stainless can be a complete PITA to work with as it cripples your tooling, drills especially but this should require almost no tooling other than the welder. There'll be just one hole each silencer for the baffles and I have some first rate drills now after making a stainless recumbent trike. Even good std shape drills are useless above 6mm. Piloted drills are needed for stainless.

If anyone has any advice or comment I'd love to hear it, particularly before I start the job.

On looking again I also need to add a lambda boss to one exhaust too.

The 2" straight through will be loud but the inserts will help some. The inner pipe size that Suzi uses is proper for best all around performance from the 400cc cylinders but we all like the looks of larger diameter. It would be better if you could find mufflers with a smaller core than 2" both for sound and lower rpm power. Removing the balance pipe also makes the bike a little louder and lose a little low to mid range power, but not enough a rider will notice.

It would also be an advantage if you could find longer mufflers, both for power and sound.

I have found it very interesting how different the sound is using different sized cores and lengths as well as inserts and experimenting is rather fun. I have that type of insert in a few of my bikes and one bike also has one of the straight through inserts that looks a bit like a cat converter with all the channels for the gas to flow through while breaking down the pressure wave.

Have fun and show pictures of how it works out.

The exhausts have now been made. Stainless 2.4" bore with a removable baffle at the rear. The 2.4" bore is needed as I couldn't just use a std reducer to the existing downpipes as the downpipes enter the std silencers at the edge of the rear of the can and not central to it. This equals a problem. The solution was to cut the end off the new silencers so it was back to the weld holding the tube to the shell. This then allows you to weld the new silencer to the old back of the cans after taking a 9" angle grinder to the old std cans. The old exhaust is just a set of straight through pipes with a piece of slash cut stainless over the last few inches doing nothing at all but making it look like some form of silencing exists to a casual observer. The old units give 89db at the rear of the rear tyre on tickover. Tomorrow will hopefully see the new units on with just the rear hangers still to make once on. I'll make a separate hanger for each can even though they're hanging off the same point. That way allows better wiggling to get them on and off.

Existing straight through and unsilenced units.



New silencers



New silencers welded to the back of the std silencers to work around the offset inputs. This does mean that all the std exhaust brightwork still fits.

The baffles are just the typical cheapie type. Nothing fancy.

Job finished.

Rear Mounts split to allow wiggle when mounting.



Baffles in



New look.





Loudness.
My cheap and chearful DB app on my phone can't split them but my ears certainly can. If the old straight through pipes were a 10 and factory pipes a 1 then these go to an 8 without baffles and a 5 to 6 with.I'm pleased with the result and can now get it in for it's MOT with at least a hope of a pass.

The MOT was duly obtained today without issue or comment. The baffles are now on the shelf ready for next year. After a few miles now under the belt I stand by most of my assessment of their impact. The open pipes had a very sharp report for each firing of a cylinder, much like a machine gun and got louder quite linearly with the amount of throttle applied. These are a more blended tone with a background noise with each firing coming through that. It also tops out to a degree at some point as more throttle has less impact on it. I'd now rate the baffleless pipes as a 7 and a 5 with them, or in other words just a bit quieter than my original assessment. Still happy with them and no plans at all to put the straight throughs back on. These are loud without being obnoxious.