6.5clone with new gx390 carb won't idle?!?

[d1333x]

Hey guys, first thread, but i got a major problem. just received my gx390 kit from NR with mikuni fuel pump and this thing won't idle AT ALL..

here is my Set-up
GX200 Clone:
-Aluminum flywheel
-ARC billet rod
-18lb valve springs
-Governor removed
-GX390 carb kit (carb adapter with pulse fitting, stock jet)
-straight header w/ RLV silencer
-Mikuni fuel pump

So i got a brand new gx390 carb and adapter and basically my problem is that my engine will start but not idle, if i keep opening the throttle it will stay on and run (i ran it for 15mins while repeatedly opening and closing throttle) when i start up the engine some white smoke comes out and if I give it some gas a large puff of stinky white smoke usually comes out. I tried adjusting the air mixture screw from half turns until the thing almost fell out, and i tried adjusting the big plastic idle screw. I also played around with the choke too. I am still pretty new to this stuff.

Heres a video YouTube - Mini Bike Problem (it runs like this no matter what i adjust)

 

[125ccCrazy]

was this a new engine or was it ran before installing the rod? were the ring gaps set (spaced) correctly?? fresh fuel? Did you check for air leaks around the carb and intake? valve lash set correctly? head torqued to spec?? lot of questions I know but this could be a process of elimination to get to the cause of the problem and then it could be as simple as the carb is just too much for the stock compression which I'm assuming is still stock since you didnt mention a flat top piston or any milling on the head..

A tip on doing adjustments on the air mixture... only go 1/8 turn at a time, if going half turns at a time you may be going too much one way or another before hitting the correct setting..

 

[d1333x]

was this a new engine or was it ran before installing the rod? were the ring gaps set (spaced) correctly?? fresh fuel? Did you check for air leaks around the carb and intake? valve lash set correctly? head torqued to spec?? lot of questions I know but this could be a process of elimination to get to the cause of the problem and then it could be as simple as the carb is just too much for the stock compression which I'm assuming is still stock since you didnt mention a flat top piston or any milling on the head..

A tip on doing adjustments on the air mixture... only go 1/8 turn at a time, if going half turns at a time you may be going too much one way or another before hitting the correct setting..

It was new, ran for a few hours, then removed gov, replaced rod with arc rod, replaced flywheel, (I have a flatop piston but i forgot to get the piston rings :hammer: so it's sitting around) otherwise it is torqued to correct specs,

I feel like the carb is too much for stock compression, since I haven't done anything for better compression. It worked fine with my gx200 clone carb when it was on. I wasn't for sure if this could be a problem or not.

 

[ianmanning26]

If you're having idle trouble its most likely your idle jet. Check that its seated correctly and that the tiny rubber o rings are there on the pilot jet plug