i ordered some uni air box vents and wanted to know how much of a difference would it make on a trx 250ex

 

Take a look at the end of your snorkle. The opening is about the size of a quarter....very restricted! The vents will help, but the little 250 can only handle so much air, so 4 or 5 is about all you can run. Run more, and it just won't jet right. Also, put them around the edge of the lid, because if they are in the middle they will hit the air filter.

While we are taking air filters, lose the K&N. Get a UNI foam filter, and save your engine!

 

keep them high so water will be less prone to getting in. I accualy preffer a outer wear on the filter and no lid and the drain tube open...makes for more dirt and maintenance, but it is too critical of a part to go un maintinaced as you know.

 

There not going to nothing but make it run lean without bumping up your jetting. A 110 or 112 main will do the trick. Bump up the pilot one or two sizes also.