yz80 carb help

[jtyam27]

I just installed a yz80 carb on my ttr125, it cranks fine on the first kick, but as soon as I touch the throttle it dies. I have already re-jetted it for the ttr, it has a 20 pilot, 145 main, and a mikuni 4 series needle. I have played with the air screw quite a lot and it doesn't seem to do any good. any ideas?

[PlanetMinis.com]

[Paxracing]

Did It Die With Choke On

[TRT]

bigger pilot and raise the needle up...furthermore the cutaway on the slide may be too aggressive allowing too much air too quickly therefore making it lean out and stall...



2 strokes have alot more velocity then 4 strokes and therefore can take advantage of the quicker air input by the cutaway on the slide....4 strokes it takes a while to get the velocity going good enough to suck the fuel through the fuel nozzle(main jet nozzle).....

TRT

[jtyam27]

I have not been using the choke it wont even try to start with the choke on.



TRT, thanks for the input, I just turned my air screw all the way in and the bike was still running so I definitly need a bigger pilot. I had not really though about the slide. I knew that it seemed like it was getting to much air but the plug said it was running rich. I was quite cunfused. I'll see how a bigger pilot does and let yall know.

[jtyam27]

Alright, I changed the pilot to a 25, and the main to a 140. It runs fine now once I get it started but I have to hold the throttle wide open and kick it a few times to get it to start. Once its started, even with the idle screw all the way out and the air screw all the way in, it is still idled too high. think maybe I have an air leak somewhere?

[TRT]

Sounds like it is a little rich on the idle circuit...try to back out the air screw 1/4 turn at a time...this will add some air...

[Paxracing]

high idled check the play in the cable



paxracingstore.com

[jtyam27]

I've checked the cable and there is plenty of free-play. I have had the air screw anywhere from all the in to all the way out and all it does is just idle higher when I turn the air screw out. I know that the manual says to turn the screw out until it causes a drop in RPM's, then turn 1/8 turn back. Only problem is, once I got it set there would be no way to idle the bike back down because my idle screw is all the way out.