[89vette]

I just picked up a very nice 2004 CRF150F. It seems to have never been touched and is 100% stock. My son is insisting that it needs a better exhaust to help performance. Is this really true or a bunch of bull? He rides it on trails.

[crfsonly]

as you know an engine generates power by igniting an air/fuel mixture in the combustion chamber. the more air and fuel you can get into the combustion chamber the more power is produced. once the fuel is burnt it has to be evacuated to make room for a new batch of air/fuel. so, the exhaust does matter. the more spent fuel can be evacuated the more room for new air/fuel. so, these aftermarket exhaust to help performance especially when combined with intake modifications. the biggest bang for your buck is going to be our PowerUP jetting kit along with a new free flowing air filter like the Twin are we carry. then you can add an exhaust but i would start at least getting the jetting correct with a free flowing air filter.

ken

[font1135]

hey just wondering what you ended up doing with your sons bike. ken was talking about a power up kit but when i mentioned that to a local shop they were very against stepping up the jets to that extent.
my bike is stock other than i just put on an exhaust, they told me to go from a 98 main jet to a 100. not a 115 like the power up kit gives you so i was just wondering how that worked out for you.