I bought the klx-S 2009 in January, it is my first bike in a long time. Additionally I am not in the least bit gifted in mechanics, I have read all of the forums here but have a few specific questions on setting up the bike for power and quietness.

So far I have done the following, removed the air box lid and snorkel.
Installed the two brothers M-7, did not like the noise so bought the reducer from 2 Bro's, still to loud, so had a welder make another reducer and inserted it.(exhaust hole is the size of a quarter now) It is not so terrible now, but still a bit noisy. I wear ear plugs, and a full face helmet and sometimes wish it a bit more quiet, other times it seems fine.

Rejetted 3-4 times, after changes.

Being at altitude(Colorado) and losing 3-3.5% hp for each 1000' of density altitude I have just ordered BB 351 kit to compensate for that.

Having read others posts about all of this, I am wondering the following.

Should I have removed the snorkel, but kept the air box lid on? Yesterday I put the snorkel back on with the lid, and it did not quiet it down. Yet I remember when I removed it with the stock set up it got louder. Wondering why it does not work in reverse.

Can I salvage this two bros system, or do I need to move to on to the FMF Q-4. (air box lid on?, insulation?)

if I go with the FMF Q-4 would I expect to lose power over my current setup?
Some people have told me I would. If so, how much as a percentage?

I plan on keeping the stock carb for now with BB-351.

I have read about replacing the header pipe, I am assuming you would need to do this at the time of the FMF Q-4 if you don't want to keep rejetting after every change. in other words if I tried the FMF Q-4 and then I wanted to change the header pipe, I would need to rejet again, is that right.

I am installing the BB351 this coming week so thought if I were to make changes, now is the time, so I do not need to keep rejetting after every mod.

Thanks so much

Thanks for the help

 

You won't lose power going from the two brothers to the Q4. The difference in those two is the size of the can. Q4 is larger so it absorbs more sound. By reducing the outlet of the two brothers you may be losing power. The closer you get to the stock opening size the closer you get to stock performance.
I run mine with the lid on and snorkle removed. With the lid off you get more intake noise.
My 351 ran fine from 8400' up to nearly 11000' in, and around, Estes Park Co.
See my settings in my signature below.
Dan

https://www.kawasakiforums.com/forum...cs-vids-33066/

 

I have decided to go with the FMF Q-4 and see how that works. Hopefully it will give me the quietness that I am looking for, with good power output.

 

the q4 killz my ears at high speeds 70+ not sure if having my airbox lid off is adding to it...

 

I had just the snorkel out with stock exhaust and at 65-70 I thought my head was going to explode. I can't imagine the whole lid off. The intake noise is pretty extreme on these bikes...

 

Having the lid off adds quite a bit of noise. Too much for me, so I only run with the snorkel removed.
Dan

 

Q4 with powercore quiet insert is very quiet with no power loss..
https://www.kawasakiforums.com/forum...t-stock-35221/
https://www.kawasakiforums.com/forum...t-stock-35239/

 

So if the stock exhaust is really loud with just the snorkel removed, then maybe my problem is having the lid/snorkel off. Two days ago I rev- up to
5000 rpm's with the snorkle/ lid on and with it off. There was no difference in sound, that I did not understand.

It is my understanding you will not get the power out of it without its ability to breath, so that is why i removed the air box/snorkel.

Should I be going at this differently?

 

the noise will come from the air box when you crack open the throttle... at 5000 rpms the throttle is almost closed, so.. no sound difference... take it for a ride at wide open throttle and some quick throttle blips wide open, you will see a difference in airbox sound for sure

 

Thanks Tiger- i will test that out, good to know.