Ok, my friend wants to take the muffle completely off of his Trailboss 325 and rejet it. it will only be off for a weekend, he will also have the RCR plain clutch spring, and take the lid off of his airbox. Is this a good idea?

Also, what is the stock Jet size, and what size should he jet up to with those mods?

 

WOW, where do I start...No, it is not a good idea. Too much trouble for only one weekend. Why would your friend want to run a staight pipe with no muffler for anyway? The carb is a stinker to get to in the Trail Boss and the bowl screws are in real tight. If your friend wants to get more bang out of his Boss tell him to get an RCR stage 1 kit and only rejet it once, instead of several times.

 

What year is the boss? They changed the airbox on the Boss in mid 2000, I beleive. So anything BUILT after that date has a #120 main jet. Anything before that has a #145. Mine had the #120. I went to a #125. Tell you what, never mind the year, look at the sticker on the front plastic ( if it is still there) and look at the build date. If it was built in 2000, you can go to partsland.com and look at the parts breakdowns. It will tell you the exact date that they changed them. I'm thinking that it might have been 12/2000. But, I totally agree with Archerr. It is not a good idea to run the bike without the muffler. I'm pretty sure it needs some back pressure, and without a muffler, it won't have any. Oh, and running without the airbox lid could possibly result in a melted piston. That's way too much air in and out and not nearly enough gas. The main jet only controls 3/4 to full throttle anyway. If You were going to fatten up the whole carb ( pilot jet, jet needle position, and air fuel mixture, it might work, but that's a whole lot of BS just for one weekend.

 

I have air box mods and I run a 150 main jet...