need some help im going riding tomorrow. put my new exhaust on and im getting flame ***** and backfires. pulled the old plug and it was black. put a new ngk in and just from running a little while its black. so thats telling me its rich. i have the mixture screw about 1 turn out so thats not far out at all. after ripping on it a little bit it seems better but its still doing it every time i rap on it and let off a fireball comes out. choke is off. ran fine no backfires with stock exhaust and never had an issue with it until i swapped the exhaust on. i figured the mixture screw would help some but i can have it a 1/4 turn out and it still does it. im lost. i didnt check and see where the needle is at but i would think it would be stock settings for the clip because its stock. someone give me some info please. have read sometimes a new exhaust will backfire until broken in but not sure. thanks

 

Sounds like you didn't rejet it. I would go up on the main a few sizes and most likely you need the next size pilot as well. The backfiriing when going from on throttle to off throttle is caused by a lean condition.

 

no i did not rejet it. what gets me is that the plug is black as coal. i figured the pipe would lean it out and that running with the winter switch on would make it about right for the moment to use the pipe but maybe not cuz it dont matter what i do it still does it no matter what. i know about going bigger jets when doing something like this but from what im seeing on the plug its black as hell and the jug is staying nice and cool so thats telling me its rich. i dont know lol im just kinda pissed at the moment

 

Backfire usually is lean. When a lean miss happens, the gas that wasnt burnt builds up until it backfires. Its probably lean on the pilot and rich on the main. Every time I put a pipe on my plug is black too. I have to go down on the main jet usually.

 

just the person i wanted to see. do you have the dg pipe on a 230s? if so what are your jet sizes so i can get an idea. this is new to me with tuning the carb with jets.

 

Me? I made my own glasspack muffler. Plus I have a different carb and no airbox.

I just remember discovering when I add a better flowing exhaust, I always had to make the main jet smaller. Which is odd because everyone online says the main gets bigger with a new exhaust. This I know for sure... the vacuum seen at the carb gets bigger when exhaust flows better. So the bigger vacuum may draw 10% more air and 20% more gas. Or it could draw 20% more air and 10% more gas. Who knows, but apparently in our cases more gas is drawn than air on the top end and less gas is drawn on the bottom end.

 

When I put an exhaust on my 230 back in the day, I went up 2 on the main and one on the pilot to get it right. This was with a Cobra exhaust circa 1989.

 

i think i am very rich on the top end and maybe lean on the bottom. my plug i took out was black. even the new plug i rap on it a couple times and did a few hole shots in my backyard lol. the new plug was already getting black very quick. i think i may leave the main alone and go up on the pilot jet. i thought about drilling it out just a hair bigger and keep going up in bit size until the off throttle backfire is gone. not sure what i wanna do. as always cheapest is best for me but i also dont wanna blow it up

 

I think you're right. You will need some mighty small bits to drill that out. They're not easy to find either.

 

Look around for oem equivalent jets. They usually run between 3 and 6 bucks per. For $20.00 you can buy a couple and make it right. The other thing is to find out just what sizes you have now and compare to stock. Maybe someone put a bigger main in for cold weather riding and never changed it again or something. Looks like 112.5 is stock for the main and 20 for the pilot.