do i need to rejet or anything if i drill the stock muffler? also is it quieter than say a muzzy to do this too?

 

Drilling the muffler out will make it a bit louder and throatier, but nowhere close to the Muzzy...
I haven't done it myself, but on a stock machine you'll probably want to richen it up slightly by turning out the pilot screw (after removing the EPA cap).
Drilling the exhaust will most likely lean out the mixture a lil bit.

 

My experience with it showed that drilling the last baffle plate made little difference in the mixture. A little less backpressure and no where near as loud as the Muzzy. A drilled baffle is only slightly louder than stock.

 

I was expecting to be surprised at how much the sound level increased, but I ended up being surprised at how little the sound level increased!

I drilled the exhaust with the expectation of doing the rejetting, crank vent and airbox snorkel mods shortly after. (Still tracking down a 13T sprocket, though!) I'd have to say that drilling the exhaust had to improve things, but nothing dramatic. With all the mods so far, it accelerates through the gears faster, but my neck and arms aren't sore from the surge in horsepower! I think the 13T sprocket will make a more noticable difference, though.

My overall mod objectives are to be able to loft the front wheel with relative ease, not concerted effort that it now requires. Although I didn't plan on it, I've just ordered a Big Gun Evo X, which will probably get me a lot closer to my objectives than I am now.

Now, if I could just find that pesky 13T sprocket!!!

Mike

 

Yep, the 13t and your big gun will make the biggest improvements.

 

I went one step farther today and drilled a 3/8" hole in the 2nd baffle. (The 1/2" drill wouldn't reach in that far, had to buy an Aircraft Extension Bit from Canadian Tire ... 3/8" was the largest they had.)

Again, no dramatic increase in noise or performance. It does change the tone of the exhaust, but nothing obnoxious.

Thinking about the whole (hole?) thing, no matter if the stock exhaust is drilled or not, all the airflow has to come out that 1/2" hole in the end ... unless that is opened up, the other holes won't improve things that much.

I already re-jetted to 128 MJ, which is a tad too rich ... maybe this will correct that.

Has anyone considered possibly drilling a series of smaller holes around the 1/2" exit?

Mike

 

if someone has the stock muffler they should dll and see whats under the back off thee muffler..that sounds llike a great idea!!!

 

I believe someone posted a diagram of the internals, and even some photos a while back, maybe try some searches. I think they or another also experimented with some additional smaller holes around the perimeter. It's in the archives here somewhere.