Carb questions

Hello everyone! I hope this thread finds everyone and their families well. I would love some help with carburetor questions. I have a’79 xs400. I have taken the carburetors off to clean and rebuild them. I have also taken the mufflers off because they are in bad shape and I’d like to replace them. My questions are; 1. Do I need to rebuild the carbs a specific way to the mufflers I get? 2. Where can I get a carb rebuild kit and mufflers that would work for me (trying for a tracker kinda look and feel)?

Welcome. Photos! Tuning is a part of the process and its something you will need to figure out. The easiest and best way to go is to keep it stock. Switching to pod style filters and open exhaust can work but there will always be issues somewhere in the tune whether it stumbles under hard throttle or breaks up at high rpm.

My bike didnt have mufflers when I got it. I went through a couple cheap sets and settled on Emgo tapered mufflers. Theyre basically Harley rip-offs and about 16" long. Everything else is stock, had to go down on jetting but I use XS360 carbs on my 400 block. 360 carbs are a little different.

What rebuild parts are you looking for? Brass or gaskets?

I like the stock theory. I agree. I’m pretty sure I liked those mufflers when I was looking around at some. I want to do gaskets and brass I guess. Did 4 on my Honda 550 with o-rings, brass, and gaskets.

The float bowl gaskets seem to hold up well if they are intact.

I use Jets R Us for OEM mikuni jets. Aftermarket jets are not good and I couldnt get my bike to run well with them. Real jets cost more but theyre better, and theyre authentic.

Sirius consolidated supplies some odd and ends. They carry rebuild kits and some come with jets. I dont use their jets. I used one of their needle jets before and the needle broke apart on me. The needle was pressed in to its base and were non-adjustable.

https://www.partzilla.com/catalog/yamaha/motorcycle/1979/xs400-2f/carburetor
https://www.jetsrus.com/
https://www.siriusconinc.com/

Thanks bro. Appreciate it. Got a carb sync cluster coming into my possession this week. Should help after I rebuild and clean up. Think I’m going to go with the same exhaust you mentioned. Gotta chase some electrical demons too after just hooking up a battery and intermittent results.

I would make a manometer. They are cheap and easy to do. I would avoid those dial type ones as they are hard to use and are not very accurate. I use mercury stix now but those are hard to get. Mine are from the 70's.

This one a member made a long time ago. It's a bit large but you get the point.

So I have modded my bike quite a bit cosmetically and functionally without any real engine changes and this first exhaust was what came with the bike which I have ID’d as MAC megaphone mufflers and likely their headpipes - iI like the looks but find it too loud and I have slent a lot of time and probly some extra part replacement $$ (electrical components) that I did not need to as I have struggled with getting tuning perfect partially due to this exhaust....the second pic are some Emgo shortys - inexpensive- that I modded (cut and reversed end to get the look I wanted but they were even louder and I later decided I did not like the look. Not to knock Emgo in my experience and as a Taiwan (not mainland China company) they are ine of the best manufacturers of parts outside the OEs. If you like the look or don't hate the look I would absolutely stick with stock exhaust...also on carbs, I would not buy any carb part that was not clearly visually compromised in some way ie a torn gasket or holes in diaphragm - jets don't go bad for example and there are lots of crappy parts out there....i returned quite a few poor quality/unneeded parts...i would concentrate on cleaning well. welcome and enjoy your project...