Honda TRX ATV Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
I have an 07 300ex and it runs like a champ. I was planning to upgrade it by pulling the air box and adding some jets. I'm running a HMF slip on and the air filter is a UNI. I ride mostly in the 1200 ft. range and I have a K&N air filter as well as a Dynojet Q101 jet kit being shipped as I type this. Im pretty stoked to get the thing Jetted but I'm kind of concerned because I don't want to mess up the mixture. This being my first quad and me not being an expert mechanic sucks.

Suggestions where to start? Thanks a lot.
 

·
Super Moderator
Joined
·
3,342 Posts
Start with telling us what size the current jets are. If it is already jetted and runs like a champ, then what more do you expect?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #4
Ok, well as I previously stated I am new to this and I'm not quite sure what jet size I have. I haven't removed the carb or tinkered with it. I do know that the gentleman I bought it from said that nothing has been done to the carb so I assume its stock? I was under the impression that jetting a quad coupled with certain mods would help you get more power out of it. The bike has a K&N air filter, no air box lid and an HMF slip on. I apologize for my ignorance.
 

·
Super Moderator
Joined
·
3,342 Posts
With your mods, the main jet should be about a 155 or 160 - no other changes needed unless there's a problem with performance at specific throttle setting. Changing the jetting does not provide a power increase, rather the jetting compliments the power increasing modifications made to the intake and exhaust. Jet changes are not always necessary for exhaust changes, but any change to the intake usually requires a jet change.

Keep the UNI and throw away the K&N (or sell it if you can) - the UNI is a far better filter than the K&N - the K&N may provide more air flow at extremely high RPM, but it only advantageous if you are racing. And leave the top on the air box unless you only run is dry areas. The air box is designed to keep water out of the intake.
 

·
Registered
Joined
·
11 Posts
I would go 40 slow and 128 main. If you go with a full exhaust, add the header, then go bigger with the main, I would get a couple, like 132 and 135, and see if runs smooth with them. You might have to adjust the fuel/air screw back to stock settings as well. Don't get crazy with that trying solve all your throttle issues. The bigger header is going to allow more exhaust flow which is a by product of jetting which is allowing more combustion to take place. Without replacing the header your keeping your machine choked up. You should also buy the Clymer's manual for the 300ex, it's gonna save you alot of trouble down the road.
 
1 - 6 of 6 Posts
Top