I HAVE A '98 300EX WITH A DG(RCM) EXAUST, K&N FILTER, AND A 2" HOLE DRILLED IN THE AIRBOX LID WITH THE CARBURATOR REJETTED. I'M GETTING A YOSHIMURA YRD RACE SERIES EXAUST. DO I HAVE TO REJETT AGAIN WHEN I PUT THE YOSHIMURA ON TO GET THE MAXIMUM ABOUT OF HORSEPOWER OU OF MY EX?

 

You probably will have to rejet again for your new exhaust. It would just depend if the Yoshimura system will give you more flow than the DG. I'm about 99% sure it offers more flow too. Anyway, it looks like you're going to have to rejet your carb.

 

SOMEONE E-MAILED ME AND TOLD ME THAT THEY PUT ON SOME KIND OF CARBURATOR THAT DON'T NEED TO BE REJETTED NO MATTER WHAT YOU PUT ON YOUR QUAD. I DON'T REMEMBER WHAT THEY SAID THE NAME OF IT WAS. IS THERE SUCH A THING? IS IT REALLY TRUE THAT THERE IS A CARB THAT YOU DON'T NEED TO REJETT?

 

The only carb you don't have to tune isn't a carb its fuel injection.I saw a pic of a 400 ex with fuel injection in a dirt wheels mag once.
Although he may be thinking about the carbs that can be adjusted with needle jets which case you don't have to change jets you just adjust the pilot and main jets with a screwdriver like with an old snowmobile.

88' 250R many extras

 

The carburetor I think they were talking about is the Quiksilver from Edlebrock. It has a fuel-metering system and a flat-side design. The thing that makes it unique is the "automatic compensation" for altitude changes. It also has an anti-slosh plate that enables it to get consistent fuel delivery. I don't know if it would work for different exhausts though. Maybe it does? Anyway, I don't know how good they are, and they only make them for the 400EX as far as I know.