I want to upgrade my exhaust on 01 honda trx300ex and am unsure how much bigger I should go with jets etc. Can anyone help me out please?

 

You will generally go up one or two sizes on the main, possibly one on the pilot. Unless you are doing other hop ups at the same time, those 3 jets should have you covered. Better yet, talk to the pipe manufacturer. They should be able to narrow that down even further. Also helps to look for a jetting tutorial if this is your first time in the carb.

 

Thanks scooter86! The obvious of asking manufacturer is something I didn't think of. I will also look into your input, it's appreciated. I also have a squeak coming from front wheel. It's on every rotation. I'm thinking it's brake related. Calipers maybe, soemthing is off, bent?

 

The squeak could be something off or bent. The front brakes are usually protected pretty well though. I would make sure the caliper releases all the way, it may need a little brake grease on the sliders or a rebuild. I would also check the wheel bearings, make sure there is no play in the wheel. If you are lucky it may even just be a small rock or something stuck in there, but probably not.

 

The bearing was done recently and prior owner gave me one for the right side he hadn't used yet. I will look it over and hope for the best. I don't need to mess with carb for a simple k&n air filter do I? The site says no yet I've read differently elsewhere. The one in there is a little messy. Has some oil residue on it. I dnot think that's good but could be wrong.is there supposed to be a small hole on the bottom of the air box? I can't tell if it is a factory hole or was done by someone. I hope the list stays short because the more I look it over the more I find. Thanks for your timely responses

 

Yes, a foam filter should have a sticky coating of filter oil on it. That is what traps the dust and keeps it out of the engine. It doesn't need to be sopping wet or anything though.

I am against k & n for anything but same riding, but if you run a pretty filter and keep the whole thing clean and oiled it should be ok. As for jetting, it depends on the machine and your other mods as well. It would be reasonable to go a bit bigger if you have an exhaust system already in place.

The hole is a normal drain most likely. Let's the water and liquid mud out so it doesn't get in the engine.

 

I domt care about a pretty filter. I guess I'm going by reputation. I need a new fliter for sure. Any suggestions?

I trail ride pretty much. Not much water or mud (yet) but would.like.to have something suitable for all.conditions.

The drain hole makes sense, I thought it was something of that sort. I've been trying to find a manual that covers everything on this quad and am having a hard time finding them. I think I need a 2001 trx300ex book for dummies haha

 

I have a Clymer for my 300ex, the factory manual would probably go into more detail on some things, but Clymer does a good job for most people.

For trail riding, just use a good foam filter like Uni or Twin Air. If you ride a lot, I like to keep a spare filter oiled and ready to go in a zip lock baggy. I like Bell Ray filter oil, you want something nice and tacky and water resistant in any case. If you find you need to move more air, I would go with an aftermarket filtered airbox lid, or fab your own. K n N for sand though, foam Sucks in sand.

 

Put in new full fmf q silencer. 122 up to 130 on main. Cleaned whole carb out. Quad will idle.for a few and die out. I think I need bump up slow jet. Engine is getting hot fast, not great throttle response. I haven't ridden yet just at idle with 1/4 throttle Rev ups. I think too lean. I adjusted idle screw some but still needs more of something. What else can I do? I domt want to run really hot and cause valve damage. I want to tune it nice obviously but need feedback on what else I can do.

 

Sure, go up one size on the pilot and see if that helps. A quick test first, turn fuel screw all the way in. Slowly turn it out, counting turns, until it starts to idle properly. Generally, if you have to go out more than 2.5 turns, you will benefit from a bigger pilot.