Replaced my carburetor with another of the same kind and swapped over the needle and jets. Of course its running like total **** until it warms up. When I first got it, I could pull out the choke, start it up, and take off. Bike ran like a dream. Now, I pull the choke, it barely idles. It pops, sputters, and backfires just off idle while riding. Plugs are always black and sooty. I have to rev the **** out of it and just go wide open throttle and it'll idle better and better, right around 900rpm when it warms up. I adjusted the float level(it was way off), new plugs/wires/coil, fresh gas. The mixture screw is only 1 turn out from seated. 48slow/190main(no shims). Im thinking a 45 slow might fix the idle/low speed. Maybe?

Any ideas?

 

So after you installed a new(used) carb, it ran fine for a while then slowly got worse?

 

I originally got a replacement carb because the 1st one just started dumping fuel through the air cleaner over and over again. I got the new(used) one and it did the same thing. Eventually figured out that it was the float so i adjusted it. Hasnt done it since. BUT, i have yet to get it tuned correctly. Even following the guides, i cant get it to run like it first did. I pull the choke, start it up and it wont idle past 1000. It keeps wanting to stall, and when i give it a little gas just creeping through my parking lot it bucks and pops through the exhaust. Only way i can get it going is to rev the **** out of it and rip down the road. Once its warmed up it idles great at 900 rpm. I think its a 48slow/190main in it right now, but thats what was always in it. Im at a complete loss.

 

Have you done a compression check on the motor?

 

I havent. The bike had been running great up until the carburetor swap. Almost like all the sudden the slow jet is too big.

 

 

Well put the origin carb back on. As stated, check for intake leaks. Make sure the enrichner / cable is not hung up. Maybe you set the float level incorrectly or the carb needs a rebuild..

 

Also if you are using the stock petcock, make sure it is working correctly.