Trouble shooting help

B

brett066

Member
#1
#1
Hello all I'm back again in need of guidance. Ok so got a new dirt kart and having trouble with the power plant. Here's the specifics: standard bore clone w/ governor out, billet rod and flywheel, honda flat top piston, ported and milled head w/ 27mm int. 24mm exh. , 1/4 pushrods, billet lifters, long single stage pipe and a gx390 carb. I am running the stock cam w/ 1.3 lifters and 18lb springs. Here is my problem, motor starts fairly easily, idles fine, and screams at W.O.T., it's the in between I can't get right. You have to baby the throttle open or it falls on it's face or even dies. You can't even remotely stomp on it. Is this jetting or perhaps timing?? I currently have the timing at stock and the 390 clone carb as out of the box. Any help GREATLY appreciated guys!!!!:thumbsup:
 
Last edited:
OND

OND

#5
#5
Hi Brett, what kinda of flywheel do you have ? ARC, Raceseng ? The new 2014 ARC's are suppose to have 32 degrees of timing built in, older ones were 28 degrees on down to 25. Probably a whole lot of cfm's in that carb, stock or bored out stock might be better. jmo
 
B

brett066

Member
#6
#6
ARC. It is the old style w/o the built in advance. i have some keyes for it, a 4* and an 8*. just was going to get kind of a baseline first. I was thinking that a stock carb would be too small to get the full potential of my other mods. Am I thinking wrong.
 
OND

OND

#7
#7
Maybe not thinking wrong, but maybe thinking to big . I would put in the 8 degree key and try it .. but if it still stumbles , try the smaller stock carb with a bigger high side jet and a bigger low side jet. jmo..:wink:
 
C

Camjamsdad

Active Member
#8
#8
I've heard the stock carb on the 212 is capable of sustaining 25hp. But like I said I thought I needed bigger, it stumbled then took off like a bat out of hell. I swapped back to a bored stock appearing carb and I still had one issue. I had to go back to the stock insulator plate to get it to run right. I also opened up the hole in the insulator plate as big as I could to get the max airflow. In any event I ended up with one bad ass machine.
 
B

brett066

Member
#9
#9
thanks guys i will give it a shot. I made a trade offer on a .625 carb on here but dont know if hes gonna take it. i do still have a stock carb, but aint too sure about the insulator plate.:doah:
 
OND

OND

#10
#10
brett066 said:
thanks guys i will give it a shot. I made a trade offer on a .625 carb on here but dont know if hes gonna take it. i do still have a stock carb, but aint too sure about the insulator plate.:doah:
Click to expand...
I seen that to, sounds like a good carb .:thumbsup: Good Luck !
If you have a stock clone carb the venturi on it should be close to .615
 
B

brett066

Member
#12
#12
Ok sorry guys not trying to sound like a nag but have a carb deal going and kinda need to pull the trigger. So..... In your(read anyone more experienced than me) opinion, would my motor be better suited for a jetted stock carb...OND I'm not sure what brand it was now, off an old baja heat black tins motor, a bored and re-circuited stock carb, or my 390 carb leaned up a little? Please keep in mind id like to sacrifice as little low-end grunt as possible. And also the fabbed intake I have for the 390 carb is somewhat long.(if that makes a difference performance wise).

P.S. You guys have helped me out a lot so far and I really just wanna get this thing tip top and reliable so I can have fun riding along with my kids on their kart. Thanx in advance!!!!!!!
 
Last edited:
OND

OND

#13
#13
Hi Brett, I believe I'll go with whats behind door #2 . :laugh: If the bored and re-circuited stock carb is done by someone who knows what they are doing. :rolleyes:
 
B

brett066

Member
#14
#14
Thanks man I think I'll try to sell some parts and start shopping. Would you recommend the .625 or .650? Are the NR-racing carbs good pieces?
 
You must log in or register to reply here.
Top