PWK Carbs

Gramatron

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Hey folks, apologies in advance for what's likely an old topic.

I'm planning parts for my build and noticed one other person who'd picked up a set of PWK carbs. After further reading I discovered that they lean the mixture on the high end for better output. But I havent seen other 400's actually running them. I know the mikesXS set is for a 650. The question is: Are fully functional PWK's doable on the 400, and have you seen anybody use them?
 
There is one guy on here that has made a set fit but far as I know not run them yet. Ido know most of the guys that run them on there xs650's are 50-50 on how they work. Some hate them some like them. The xs650 motor works well in the low to mid range where the xs400 is more of the top end. I would think there will be a lot of tuning to be done to make them work perfect. People are still trying to get the mikuni vm carbs setup perfect for the xs400. I still say a good well setup set of bs34's are the best bet for the sohc xs400. I prefer the early style used on the xs360's. I have set off a 76 xs360 on my 80 and love them.
 
They are usable and you can get them to work, just don't get excessively big ones. And don't buy the Mike XS ones. They are knock offs, and by the time you swap in proper Kehin parts, it ends up being cheaper just to buy the legit carbs.
 
I did a fair bit of searching around for aftermarket carb info for our bikes and there is not much out there. If your stock ones are useable I would keep them. Mine were stuffed and I didnt want to chance a second hand set from overseas. Ended up getting a pair of Vm30 roundslides. Im led to believe flatslides are a bit tricky to tune for a streetbike and roundslides are a nicer compromise. Vm30s are damn cheap too. I havent worked much on the bike lately however last time I had it running the vms seemed to work well and the jetting I had would be a good starting point. Heres a thread with some Info http://www.xs400.com/forum/showthread.php?t=13018&highlight=mikuni+rich
 
When it comes down to it, any appropriately sized carbs will work just depends how much stuffing around you want to do tuning it obviously. I chose the mikunis because theyre pretty common cheap and plenty of cb guys use them. Flatslides would be cool though
 
Ah you guy's are awesome, thanks. I'm not afraid of tuning but if flatslides aren't a great idea I'll ditch the prospect. My stocks work fine and I plan to re-jet but I'd love to optimize engine output in any ways possible. That's why I ask.
 
Yeah man well its up to you its always good to see people doing something different, most of the time it comes down to $$$. Mikuni tm's might also be a cheap option
 
I will say this based on other applications I've used the PWKs on- instant throttle response. Puts CV carbs to shame.
 
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