exaust sub ports

elf · Feb 29, 2004

I was wondering how the sub ports work, I recently tore down my motor and was cleaning my power valve. when I was done I was moving my PV arm up and down while looking in the exaust port. My sub ports do not open, are they supposed to? I noticed they have a slot cut in them and when in the right position you can see into the cylinder through the sub port.
my understanding was when the PV opens so do the sub ports to get more exaust through for better top end. With all my marks lined up, the sub port slots are on the opposite side, in other words closed when you move the accuater to raise the pv the sub ports are still closed. I just dont understand what good they are doing. Oh by the way this is on my ktm 144 that Eric did for me. And the pv was set up by him too.

Jman271 · Mar 1, 2004

:cool: The subs on that bike need to be lined up w/ the timing marks on the actuator arm and barrels. Looking at the pv assembly the sub barrel to the left has 1 mark, the other on the right has 2 marks, the one in the upper position is the one that moves the large flapper and has 1 mark. As the actuator arm is raised and the large flapper goes up, the barrels also open and the cupped side of the barrel pours out into the main exh. If you are saying that it is opposite, they are in backwards, it should be 1 mark on the left, 2 marks on the right. The actuator arm has marks on it that should tell you which side needs what barrel. The idea is that as the main flapper raises, the subs raise along w/ it. I have the repair manual on CD from KTM, I will look to see if I can send you a link or page that has the info on it, am I making any sense? When the pv is in the closed position, you should see the shiny back side of the sub barrels and as it is raised, the cups gradually get exposed, sorry if I rambled, post back,,,Jman271

elf · Mar 1, 2004

Yes your making sense. That is what I thought was supposed to happen. but the grooved section is 180 degrees in the other direction. I had all the marks lined up with the one with two marks on the right side I even tried switching them. Neither side even comes close to opening. If you still have your bike apart you should check yours. I have been messing around with this thing for hours now. I got it to work the way it should. the left gear is 4 teeth from the mark and the right is 3 teeth from the 2marks. now when i push my arm up the flapper goes up and the subs open up. So is this the way I should put it back on the bike? Could the marks be that far off? It certianly appears that way.

Jman271 · Mar 1, 2004

You have to time the large flapper first, so the line marks up and the actuator arm is all the way in the closed position, closest to the base of the jug so the large flapper is bottomed out, but the mark lines up. Then, spin the side barrels till they line up w/ the marks, fiddle w/ them so they slide into their slot, now as the large flapper starts to move up, it takes the subs w/ them. Do you have adobe acrobat???
PM me your e-mail, I lost it, I have the manual ready to e-mail,,,,I can't post it is 11mb.

elf · Mar 1, 2004

The large flapper mark is lined up. I do have adobe. With the top mark lined up and the right-left lined up they dont open. Right now I have the large flapper on the mark with the arm all the way down. left side 4teeth off the mark right side 3. when I push up the arm the flapper moves up and the 2 side ports open up. if I pull down on the arm the flapper comes down and the side ports close. I have tried every other combination and none of them work.

Jman271 · Mar 1, 2004

"if I pull down on the arm the flapper comes down and the side ports close. I have tried every other combination and none of them work."
This is the right way, now I am confused!!! Send me an e-mail to jbonemotorworks@yahoo.com

marcusgunby · Mar 1, 2004

Im sure on mine the timing marks were way off as well.

elf · Mar 1, 2004

On your new RM ? This is the first time in my life I have bothered to look at somthing like this. I guess after joining DRN I am now much more aware of what is going on inside my motor.

marcusgunby · Mar 1, 2004

Nope the KTM i had.

exaust sub ports

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