i have a 01 400ex and i just put the biggest stage 2 jet in it. also have aftermarket airfilter with the air lid removed and a tunable white brothers e series pipe. on the end of the muffle there are about 10 spacers with a blockoff plate on the end. i guess the spacers act as a vent for the exhaust fumes. how many of those spacers should i remove and should i keep the block off plate or remove it? thanks!

 

you put the biggest jet from a stage 2 kit in? is that the one the pipe manufacturer suggests? I would follow the instructions with the kit. your pipe also might be adjustable, more spacers will probably make more noise but give the most power, less spacers for less noise, etc.

 

Fewer spacers will cause more back pressure, and favor torquey low end power (like for trail riding). More spacers will be more free flowing, and that will favor top end speed (like for going fast in open country).

The obvious sound issues have already been mentioned!

It is a mistake to put a jet in, then try to tune the exhauset to match the jet. It should be done the other way around. But, by going with a big jet at least you aren't burning up your motor from running lean.

Pick the number of spacers you want to match your riding conditions, then back down the jet size until it starts to just run lean. Then go back up a size for a little margin of safety against being lean. You are going to have to deal with the needle and all that other stuff as well, so good luck because you don't sound like an experienced tuner....

 

ive never worked on a 4wheeler motor in my life and it only took me an hour to take the carb apart to put the jet and the new needle in and put it back together (i had to take it completely apart because the old jet broke off). but it fired up and ran awesome so not bad for my first attempt. the 4wheeler came with the exhaust on it already so that one is not myfault.

so what about the block off plate on the end of the muffler? should i keep it on there?

 

Do a plug check and be absolutely sure it isn't lean. Lean engines run "awesome"....until the point where your piston melts!

Without the plate, you will be wide open. It will be horifficly loud and there will be no spark arrestor any more....and of course you will have to start over with the jetting.....

 

im gonna pujt the spacers back in tomorrow and the block off plate tomorrow and put the rest of my goodies