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-   -   Mod day - Airbox, carb, smog, crank case breather, carb 'T', and muffler completed (https://www.kawasakiforums.com/forum/klx-250s-71/mod-day-airbox-carb-smog-crank-case-breather-carb-t-muffler-completed-8886/)

Amunoz2121 Mar 14, 2015 09:55 PM

2 Attachment(s)
KLZ678 Thank you very much.

just curious, what does the vacuum line going into the carb actually do? i mean its there for a reason right?

Attached is what ive seen from a few other threads. Since im running just a pod filter it would be WAYYYY easier for me to plug this fitting like the images and remove all the smog stuff. just didnt know if it would mess anything up.

Thanks again!!!

klx678 Mar 15, 2015 12:31 AM

Of course it has a function - it operates the fresh air valve for the exhaust port when necessary.

You will do fine with it plugged.

I guarantee you that you will be doing some serious jet work with the pod. I don't know who has trodden that territory before, you may want to search or post the question to see if anyone has.

Klxster Mar 15, 2015 03:22 AM

One thing I've read is that putting on a pod ( or other similar mods ) causes the loss of the required 1psi differential between ambient air pressure - which resides above the fuel in the bowl - and the air pressure at the intake bell of the CVK - more specifically at the MAJ port on the intake bell. Which causes the delicate balance of air to fuel in the emulsion tube (needle jet) to go FUBAR. This information is online and from someone who was trying to impart his wisdom of the inner workings of the CV to us Cro-Mags out here yanking off airbox lids and, worse, putting on filter pods..lol..

Our CVK does not have replaceable MAJ's and the design of the MAJ is complex - a long taper to a small orifice... You can drill it out and thread in a fuel jet but it will not have the same flow characteristics as the Keihin MAJ.. And I cannot find information on what jet sizes might restore proper functioning of the emulsion tube.. This is a real problem that I think is holding back our power levels by keeping our AFR's lean..

Amunoz2121 Mar 16, 2015 03:55 AM

4 Attachment(s)
thanks klxster and klx678 again,

I kind of regret it, but i did about zero research on everything before i started chopping up my bike. I just knew what i wanted in my head so i started doing it/ordering parts at the same time.

it all started from some bent handlebars. I needed to replace them and then i started tearing off all the body panels, exhaust, airbox, gas tank. decided i am going to do the pod, if it works, do an under-tail muffler, chopped the rear frame right after the seat mounts, redoing all the turn signals, brake and rear running light, relocated the coolant res and battery, going to lace up a matching 18 inch rim for the front. basically turning it into a custom looking supermoto style KLX, prob 80% street 20% offroad.

I ended up doing a jet kit on the carb two nights ago. I ordered it from 6 sigma, where you tell them what you did to your bike and they send you a custom jet kit. Im really really banking on them sending me the right kit and parts so i dont have to pull the carb again and readjust. (wishful thinking probably)

I followed their suggestions that came with it...Put two shims on the needle jet, put a 127.5k main jet in (came with three main jets, a step above and below the 127.5, instructions suggested using the 127.5) #38 pilot jet, backed the mixture screw out three full turns.

thinking about putting up a gallery and write up of what im doing. from the little research ive done and comments from buddies, i dont think to many people are doing what im doing right now with their KLX250s.

again, really appreciate the info guys, first time doing something like this so all the help is very useful!

first two pics are with no handlebars, frame is stock, second two pics are with new bars, frame is chopped after seat mounts and rejetted carb with pod filter installed.

Klxster Mar 16, 2015 04:55 PM

Wow, that's a lot of modding! I'll be nice to see your progress..

mvs Mar 20, 2018 08:36 PM

6 sigma
 

Originally Posted by Amunoz2121 (Post 519085)
thanks klxster and klx678 again,

I kind of regret it, but i did about zero research on everything before i started chopping up my bike. I just knew what i wanted in my head so i started doing it/ordering parts at the same time.

it all started from some bent handlebars. I needed to replace them and then i started tearing off all the body panels, exhaust, airbox, gas tank. decided i am going to do the pod, if it works, do an under-tail muffler, chopped the rear frame right after the seat mounts, redoing all the turn signals, brake and rear running light, relocated the coolant res and battery, going to lace up a matching 18 inch rim for the front. basically turning it into a custom looking supermoto style KLX, prob 80% street 20% offroad.

I ended up doing a jet kit on the carb two nights ago. I ordered it from 6 sigma, where you tell them what you did to your bike and they send you a custom jet kit. Im really really banking on them sending me the right kit and parts so i dont have to pull the carb again and readjust. (wishful thinking probably)

I followed their suggestions that came with it...Put two shims on the needle jet, put a 127.5k main jet in (came with three main jets, a step above and below the 127.5, instructions suggested using the 127.5) #38 pilot jet, backed the mixture screw out three full turns.

thinking about putting up a gallery and write up of what im doing. from the little research ive done and comments from buddies, i dont think to many people are doing what im doing right now with their KLX250s.

again, really appreciate the info guys, first time doing something like this so all the help is very useful!

first two pics are with no handlebars, frame is stock, second two pics are with new bars, frame is chopped after seat mounts and rejetted carb with pod filter installed.

I just ordered the 6 sigma kit for my 2007 old 250s.
I'm at elev. 1000 feet but ride at elev. 2000 feet.
How do you like the sigma kit?

mvs Mar 21, 2018 11:50 PM

Crankcase vent
 
I don't understand why the factory put the crankcase vent in the bottom of the Air box.
It seems to me that if it got water in the Air box it could get into the crankcase easily from there.
I'm removing the smog stuff anyway so I thought I'd replace the crankcase vent hose straight up about 7 inches and put a cheap PCV valve in the top of the hose. Then run the PCV valve drain hose into the hole where I removed the smog hose from the airbox, thereby eliminating potential water entry to the crankcase while remaining environmentally friendly.
Any thoughts from anyone?

klx678 Mar 22, 2018 12:32 PM

That really isn't environmentally friendly. Environmentally friendly would be to do something like that without removing the rest of the smog gear. After all, THAT is the main smog system, venting air to the exhaust to finish burning any unburnt gasses. All the breather does is vent some fumes to the air box, a small bit of smog compared to the unburned hydrocarbons in the exhaust that escape without smog stuff on board.

But regardless, your idea makes sense. I would do it. As for my opinion on the rest of the smog equipment, it would be more advantageous for me to lose five pounds than to save that pittance of weight and it doesn't add any serious mechanical complication - aka I'm too lazy to take it off and plug the holes. Besides it does nothing for performance to take it off or leave it on.

RaceGass Mar 25, 2018 07:26 AM

Funny how this thread popped up. I read n retread this thread while doing my big bore kit. Certain pics didn't load so I'd use the service manual and ask questions here. It worked out ok funny how I'm back working on another one

LaGrasta Feb 11, 2025 07:41 PM

DefaultSMOG now removed, but am confused on what carb port is capped.

the two black plastic ports: lower, to tank (fuel inlet)
higher, vent to ground?

brass outlet on other side, capped?



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