Stock motor, Aftermarket headpipe or stock?

[sprtrx300ex]

After reading through some of the threads on the site, i have noticed that some people have siad that adding an aftermarket headpipe to a stock motor will actually cause u to lose power :confused: .

My 300 is stock as far as the engine goes. I am getting a White brother E-series silencer, and I was wondering if I should also get the headpipe? Please help out in any way possible.

THANKS

[sweet300ex]

Well, for the 300 they dont make an s bend, so you have to get the pro meg, which wont fit onto the stock header, so you have to buy an aftermarket one. The 300ex's stock head pipe is so bad you should get another one anyways, it will help.

[sprtrx300ex]

The Pro-meg wont fit onto the stock headpipe? Ok, then if I get the complete system will I notice an increase in power instead of a decrease right?

[sweet300ex]

Originally posted by sprtrx300ex
The Pro-meg wont fit onto the stock headpipe? Ok, then if I get the complete system will I notice an increase in power instead of a decrease right?
thats right, you will deffinatly see an increase, trust me, I have one

[sprtrx300ex]

Alright cool. What size jet do I need. Do I need to move the needle clip at all? I plan on running 12 discs with the quiet core for around my house, but when I go to tracks I will be removing the Q-core.
Thanks for your help.

[Diedrich]

yeah get a full system

[remlapr]

for 300's full systems are the best even with stock motors. The loosing power with a stock motor and full system thing is for 400's

[fazlo321]

Humm... I'm runnin' pro circuit header and pipe, i didn't notice any power drops?? I can ride a wheelie in 3rd now.

[sweet300ex]

Originally posted by sprtrx300ex
Alright cool. What size jet do I need. Do I need to move the needle clip at all? I plan on running 12 discs with the quiet core for around my house, but when I go to tracks I will be removing the Q-core.
Thanks for your help.
im not sure about the jet sizes, for some odd reason i didnt have to re jet mine, the plug looked fine, and ive run it ever since x-mas of 02 without re jetting, but you may have to go up 2 sizes on the main jet or something llike that, im not to good at jetting

[TRX_Thumper]

yall are smokin somethin back when i owned a 300 i had a white bros on a stock header...........:huh

[Scottydawg]

get the head pipe for sure. what are you acomplishing
if you leave that pencil size head pipe on in front of that
new silencer your buying?

modify your air box lid and make a minor jet adjustment
and you will reap the benefits of your work.

i was very happy with my 300 after i repiped. realy helps a 300.

DMC Alien, custom lid mod similar to EHS and K&N.
jetted to dmc specs.

:confused2

[cals400ex]

for jetting specs, all you need to do is call up white bros and ask them what to do with the main, needle, and pilot. you will only need to tell them which pipe you have and maybe your altitude. they will probally also send directions on what jet is recommended with the pipe.

[sprtrx300ex]

alright Thanks for all the responses.
What will adding the quiet core do to jetting? Will it make it run richer or leaner? Im just tryin to gather all the info before i buy it.

Also, I read somewhere that the reason 300's pop on decelleration is because of 3 things.
1. Low octane fuel
2. lean mixture
3. The air tube that comes out of the top of the cylinder is what causes it to pop.

Anyone ever heard about #3? Does this mean that it will still pop even thogh everything is jetted right?
Thanks again!

[ryanh250ex]

i'm no expert on the WB systems or 300ex's, but the quiet core will make the mixture richer. this is because the quiet core will make more more backpressure, hence making less overall power, and makes things quieter. backpressure affects jetting, and when backpressure is increased, airflow is restricted further. with less air, less gas is needed for optimum performance.

[sprtrx300ex]

Also, I read somewhere that the reason 300's pop on decelleration is because of 3 things.
1. Low octane fuel
2. lean mixture
3. The air tube that comes out of the top of the cylinder is what causes it to pop.

Anyone ever heard about #3? Does this mean that it will still pop even thogh everything is jetted right?
Thanks again!

[TRX_Thumper]

your 300 is popping on decel because you are lean on the pilot...up your pilot jet one or 2 sizes...may have to play with the fuel/air screw also ...not the idle screw

[sprtrx300ex]

my 300 is stock tho, it shouldn't need to be rejetted. Does anyone's 300 NOT pop?