removing spark arrester

[hondaluvr]

I have a buddy who removed the spark arrester from his stock exhaust, the bike is totally stock. It is a lot louder and he claims to have gained lots of power. My question is this-would there be power gains and would jetting be required or are there any side-effects?

[spazzy973]

i did this on a 400ex before i would not call it a big gain but the engine did breath better and no you do not have to rejet

[bwamos]

Yea you'll get a little more torque on the bottom. Frees up the airflow.

You will, however, want to go up 1 size on the mainjet. Honda is right on the Lean limit as is because of EPA emissions crap. So 1 larger is the best even without removing the arrestor screen.

I did it to mine and it needed a bigger main jet.

makes it loud, but not a good lound. more like noisy.

[Ridin' Jesse]

i did and i didn't have to rejet

you dont have to rejet. but it runs incorrectly if you dont. you can run aftermarket exaust on stock jet if you wanted to but it would run like chit.

changing the jets the 1st time is a pain. but after that you figure it out.

[spazzy973]

when i did it to mine i did not have to rejet and it ran just like stock but with a little more torq and as far as it being loud well it really sounds like it is under water or in a tunnel

[Ridin' Jesse]

yeah i did notice that it was alot harder to kick...i think that it was something with the back pressure, and the air to gas ratio wasnt close enough and caused for a really "fun" time to kick...expecially in the cold.

[DeerNuts]

Originally posted by mittimj
.
changing the jets the 1st time is a pain. but after that you figure it out.

:huh What's so hard about it? Im not mechanically inclined and it was about the easiest thing Ive ever done.

[mastinson]

Will it hurt an engine to remove the spark arrestor without rejetting?? (blow it up from running to lean)