XS 650/750 Flat side carbs

Leslie

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My big bore kit has been completed (Smedspeed) my engine is now a 750cc, has anyone carried the 750cc conversion with different carbs other than the Mikuni CV, ie Mikuni flat sides


engine 9.jpg
 
Think most people use different carbs to the original cv carbs on their 750 engines, I use dellortos, most people use mikuni round slides, but ive never had muchluck with these, even got a pair of amals set up in the garage,
 
I converted to VMs with longer manifolds. Super easy to set up,runs better and better response. Only a 650 though.
 

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I have BS38s on my 750 BBK and I am too stupid to know better but playing with jetting has made it a rewarding ride. I am of an age that I am not racing friends corner to corner nor enduring the vibes of a top speed run against modern 4 cylinder contemporaries. My current project came with TM34s and I will try to deal with them after a bunch of research. We have 50 year old bikes that can be tuned and modified for pretty decent HP. But for the same $ we can obtain a CBR, FZ, YZF, KZR, etc . Point being if we wanted "rocket fast" we would not be on a "XS650" forum.
 
No experience myself but here is a link to a thread that may help.
https://www.xs650.com/threads/rs-36-mikuni-carb-fuel-consumption.61963/
RS carbs are available as kits for XS 650/750 from several Mikuni suppliers.

Just a thought I had when looking at this The GPZ/EX 500 carbs are a spaced correctly for XS 650 heads so ...
https://power-barn.com/kawasaki-ex500-keihin-cr-special-racing-carburetor-kit/
You would be on your own so far as setting these up and I am not sure if there is enough room to mount them on an XS. You will need to research. That said they are very good carbs.
 
Mikuni oz sell RS flat slide kits for XS650 big bores, so I'd imagine other stateside suppliers would also sell them.
 
My big bore kit has been completed (Smedspeed) my engine is now a 750cc, has anyone carried the 750cc conversion with different carbs other than the Mikuni CV, ie Mikuni flat sides


View attachment 238004
I've got a 707, smedspeed cam and tm32 flatslides. What were you thinking?? I've noticed in your pic you have 2 coils. I'm guessing you've gone for a re-phase as well?
IMG20210810212251.jpg
 
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I've run both VM34s and VM36s in 750 kitted bikes but never flat slides. The 34s worked best for everything but very top end and very easy to set up. The 36s are harder to get to respond at lower RPM. I was thinking about doing VM36s with UFOs in them on my current build to see if it helps that low end response but haven't saved the pennies for them yet. If anyone has any experience with the UFOs in 36s I'd love to hear about it good or bad before I pull the trigger.
 
I've run both VM34s and VM36s in 750 kitted bikes but never flat slides. The 34s worked best for everything but very top end and very easy to set up. The 36s are harder to get to respond at lower RPM. I was thinking about doing VM36s with UFOs in them on my current build to see if it helps that low end response but haven't saved the pennies for them yet. If anyone has any experience with the UFOs in 36s I'd love to hear about it good or bad before I pull the trigger.
Packrat the engine has also been re-phased to 277 as well as the bigger bore 750cc, I will be attempting to wire her up shortly, I am crap with electrickery (White mans magic) and not predicting a quick resolve to the start up :rolleyes:
 
I have big bore XS and Mikuni tm34 carburetors. They have been quite good, although I haven't used their full capacity. I need to take it to a good tuning shop to get full use out of them.
 

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