questions for fabricating an exhaust

Okay so i talked to my brother who is a very skilled welder and fabricator and while coming up with ideas for Christmas we decided on making a new exhaust for my bike since the current 4-1 kerker is rotting away.
 
Im aware that the primary pipes are 1.5" and the collector is 2.5" on my kerker. We are most definitely going to make a 4-1 and I want to keep the sound at a high-pitched "singing" tone and not too much deep rumble although the deep rumble sounds nice at idle. Not too loud, not too quiet. How does one achieve these characteristics?

A lot of my questions come from routing the exhaust. I really dont want to take off the exhaust for removing the oil filter but I also don't want to have too many bends in the exhaust. This is what I was thinking but I am up for ideas! 
I also am struggling with muffler options. Should I stick with the 2.5" collector or go to the 2" collector that has more options? What are the drawbacks? How do I consider exhaust scavenging?

A lot of this post is just forming ideas and gaining insight on how all of this works. That said, if you have a cool idea, PLEASE SHARE IT!!! I really want to make this creative and fun so that I can have an awesome time with my brother!

Edit: i never considered making my own muffler but if its not too hard I would like to hear about it!

Shortening the headers to the collector will reduce top end power - the bore of the system will determine where in the rpm range power is made - smaller gives more low down and midrange - bigger is more top end. If you go back through my build it may give you some ideas for the muffler. Take a look at the design of delkevic headers which I believe give oil filter access. Back in the day a friend’s dad used to race British bikes and he had different exhausts for different circuits ( twisty or long straights)

I've built exhausts for all my zeds ( and others ).
Regardless of the header and link pipe diameters you want to go for a 27" header length from head to collector for the Zed motor.
This is the proven sweet spot for all round performance.
If you want similar characteristics to the Kerker you should go for similar dimensions with the head and link pipe diameters.
For the "silencer" i always go for the canister type with a non restrictive wrapped perforated tube baffle.

Also keep in mind:
If you position the collector or the header pipes too far to the right (and possibly too low), your lean angle will be severely restricted very quickly! -

((Personally, I’d rather remove the tailpipe and collector—or even the entire system—for an oil change, than ride a system that scrapes the ground too early when cornering. Of course, if you only plan to ride straight lines on a drag strip, that’s a secondary concern ))For example: with my 4-2-1 system, I always have to remove the tailpipe and collector—and "spread" the headers—to get to the oil filter during an oil change. But I’m happy to do that once or twice a year; in exchange, I get an exhaust that is guaranteed NOT to scrape during fast right-left corner combinations—lateral ground clearance is simply more important to me!



 
 

Copying that Kerker would assure you wind up with a good performing system.  Some lesser exhaust systems are just a collection of bent tubing, not a tuned system.

I was hoping to keep the oil filter access but if it means i will have a good performing system I can accept the drawbacks of removing the exhuast. @zed1015 you dont happen to have pictures of your creations do you?

Good catch MPF-Joe! I never considered lean angle. Although if im being honest after my crash I've been too scared to push my machine like I used to. I think im going to follow Nessisms advice and copy the 4-1 kerker design(s) that I have OR maybe consider that 4-2-1 design that MPF-Joe mentioned. What are the advantages and disadvantages of these two systems?

I have two different rusted out kerkers, the one in that picture which does give oil filter access and a different one which goes straight down and covers the oil filter. If the other kerker is better flowing I would opt to use that one instead. Decisions, descisions!!

Also im still trying to decide what the collector OD should be for where the muffler attached. Does it matter if it is 51mm or 63.5mm? I find a lot of 51mm mufflers around. Would it be a bad idea to have the 63.5mm outlet and install a reducer to put a different muffler on?

As always I will share pictures of what we end up making or I'll just start a project post to centralize all that I'm doing to my bike...

Anther example:




I once had a 4-into-1 exhaust system on my Z1B. I bought the bike—equipped with that system—from the US, and to this day, I still don't know who manufactured it. I’ve seen it in photos of US Kawasakis quite a few times, usually in a chrome finish... In any case, my 900cc engine ran absolutely fantastically with it—even after I’d bored it out to 1015cc. It offered strong pulling power across the entire rev range, and the oil filter remained easily accessible. Of course, it wasn't exactly the "prettiest" 4-into-1 system imaginable, but for me, it offered every advantage: no loss of power, good lean angle clearance, and ease of maintenance! That’s why I kept it on my bike for 20 years!
 

This is a 750 twin build, and well worth reading the whole thing. I believe the exhaust build begins on page 14. Since the 750 has bigger cylinders, the dimensions will not be exactly what you need, but you can get a better understanding of the theory and what you are up against in designing a custom system.

kzrider.com/forum/11-projects/598240-sav...0-750-twin?start=156

I looked through that 750 project and there is a lot of good info on there! I also appreciate everyone's input so far. I think for now I'm going to copy the original style kerker that covers the oil filter simply because it is easier to make and probably flows better. The only thing that im struggling with is whether the primary pipes should collect into a 2.5" (63mm) pipe or a 2" (51mm) pipe. The main reason i would want the 2" pipe is because its so much easier to find slip-ons or any kind of mufflers in that size.

As to why I think that it doesnt matter too much, many sport bikes have the 2" collector, even big bikes like the gsxr1100. Again though I know almost nothing about these topics and thats why im asking. Could someone shed some light on this for me? If someone says its fine then ill probably go ahead with this plan. Argh! A part of me wants to keep the 2.5" collector design!! My brain is so jumbled   Once this is figured out we can finally start moving forward...

NOS

🙂


V&H 13009J fitted in 2012

daveo wrote:

NOS

🙂

V&H 13009J fitted in 2012

Daveo... what in the world. That thing looks so good it almost seems fake... I love the looks of the kz1000a shaft and thats why I got the tank from one. I also love the tail piece from the kz1000j so I will be attempting to install one to my bike. Once I get that stuff all together I will be starting a project post. Something to look forward to! Also, that V&H header is a gem but hangs really low. Do you have issues with it like that or is the clearance good?

Rolled off a curb once , and capped a few tall speed bumps... 



There is plenty of ground clearance, but I had to learn the hard way about those obstacles. 

🫣


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