Carbs and jets

[Tapps]

I have just removed the CV carbs from a running 1979 XS650.
I am going to be running PODS and straight pipes..
What size jets and needles should I be looking for?..
Also, can I just get a different size intake manifold, as the new carbs are slightly bigger?
I will try and enclose pics of what I took off, and what I have been given..

 

[grizld1]

The cable top carbs in your photo appear to be Mikuni VM36. If that's correct you'll find baseline jetting in the VM section of the XS650 Garage USA Carb Guide; press the Tech button, scroll through the menus, click the link, download, and read. Come on back if you still have questions.

 

[gggGary]

Are those Snowmobile (two stroke) carbs?
If so you got a long row to hoe.
Hint don't throw out those stock carbs just yet.
The Griz is the expert here, not me, I just fumble around.

 

[grizld1]

Expert?! You know better than that, Gary, I've just screwed around and made enough mistakes to avoid a few. Those look like regular VM36-4 aftermarket carbies. Unless they were set up for 4-stroke use by somebody who knew what he was doing, every piece of brass except the slides will have to be swapped out.

 

[gggGary]

Looks like they are also BOTH LH carbs.

 

[gggGary]

Tuning a set of "designed for XS650" brand new VM34's is often an arduous process, starting with a pair of random old "free" carbs? Woosh You gotta be tough or damned lucky.

 

[grizld1]

The VM36 is made only in a "left hand" version, Gary. I installed cable pull choke actuators in mine, with a late 1960s Suzuki handlebar choke control from ye olde salvage stash.

Guys tend to make the tuning process harder than it has to be by failing to get everything else right before trying to tune carbies, taking shortcuts, making multiple changes at the same time, and not taking it seriously when they're told that every change is going to have secondary effects, upstream and/or downstream. And of course there are the guys who swear that they've done their reading, then ask questions that make it clear that they skimmed the material but didn't read it. It ain't rocket science, but a little laziness at one extreme or frantic thrashing at the other can make things seem about that hard.

 

[Tapps]

Looks like they are also BOTH LH carbs.

 

[Tapps]

They are...but with the way the hardtail is, I can make them fit.

Its, the difference in diameter that I'm concerned about too.
I think will have to get new intake manifolds...
I'm just not sure if I'm wasting money.

 

[gggGary]

Are the stock carbs in reasonable shape? Running stock carbs is usually the simplest way forward even if they need some brass and other work. To use those VM36, start by finding and pricing the right manifolds Then inventory the brass, find a set of brass and slides with the correct cutaway (if needed) that (might) work in Griz reference above, price that. Then look into cables and throttle to use those carbs.

 

[Tapps]

Are those Snowmobile (two stroke) carbs?
If so you got a long row to hoe.
Hint don't throw out those stock carbs just yet.
The Griz is the expert here, not me, I just fumble around.

I just wanted to say thanks for your help last year on my first build. And show you the finished result.

 

[Tapps]

I just wanted to say thanks for your help last year on my first build. And show you the finished result.

Btw, ended up with 130 main, and 27.5 pilot.
And won the race!

 

[grizld1]

CONGRATS!!!