CB175 only idles if Idleadjustment screws are full in

[Crim]

So I have a cb175 that will only idle at ~2000rpm if I have both idle adjustment screws on the carbs dialed all the way in. With both all the way in, the idle is stable at 2000rpm, but if I back either side out, or both sides out just a little and it'll die pretty quick (within 15 secs). Can anyone help me figure this out? I'm guessing it's idling off of the main jets at this point..

I'm running stock jetting, and have cleaned/adjusted the carbs per the book, and verified them a billion times now. I've adjusted the points gap, and set the timing bang on. I replaced the pistons/rings with 1mm overbore about 2 years ago... and more recently (last week) I had the heads off to replace stripped out spark plug threads, verified that the pistons and all look good inside. New spark plugs gapped appropriately..while trying to set the idle I have one of those jump-start battery packs hooked up to the battery in the 175, along with having a brand new battery in the bike, I'm positive that battery power is not an issue here.

At this point I'm fairly sure this is a carb problem, but am stumped where to go from here...any help is appreciated! What do you guys set your idle fuel/air screw to? Perhaps I'm doing this piece wrong?

Thanks
Stephen

 

[skatetheame]

Stock air box, and pipes?

 

[Crim]

Currently no air box, and CL high pipe exhaust. I did pull out the stock airboxes that have new filters and hooked them up, and it made no difference. The last time I pulled the carbs apart I just left the airboxes off.

When I first rebuilt the motor about 2 years ago, it had no issues with idling running this exhaust and no air boxes and the current jetting.

 

[my-79-750-k]

Sounds like a fuel starvation issue. Did you replace your fuel lines as well? Add a filter? Rebuild the petcock? Clean out the tank? Little pieces of crap in the lines would cause it to starve for fuel, and unless you've got the idle jacked way up, like you have now, it'd end up shutting down.

 

[Crim]

Good call. I believe the petcock bowl has been cleaned recently, unsure about the tank and lines. I'll check them out tomorrow!