i have a 300ex and i just got a full yoshimura exhaust for christmas how reliable is it and how much do i need to jet the carb.

 

Yosh is a top name in exhausts, you got a good gift !! A full system is the only way to go for the 300ex, the stock head pipe is so tiny. Jetting is recommended, maybe even running without the lid, or putting a few holes in it, the only air inlet is a couple of frame tube holes in the bottom of the box !!. The only thing I found with most Hondas, especially the small ones, is the rev limit is very low, with the motor breathing so much better, you may find yourself shifting a lot more, and you may hit the limit on WOT at top speed. When I put exhaust and air box mods on my son's 300ex, it sputtered bad when run hard, had to shift to keep the rpms under the rev limit, jetting was spot on, went up 2 sizes on main, and one on the pilot jet, with a few holes in the lid. I ended up putting a CDI on it with a +1000 rpm rev limit, made all the difference in the world, lets you get all the power out of the new mods. Either that, or you could put a different set of gears to put the rpms in a lower range, but by the time you put sprockets and chain on, you will have almost as much as a CDI, check eBay, that's where I got my CDI at a better price than buying from a catalog.

 

thanks