Awhile back, I installed a HPD trail pipe with an RCR silencer. This, along with some other mods I did at the time, made a huge improvement in performance. After riding with some people last weekend and getting lots of complaints about excessive noise, I kept the HPD pipe but switched back to the stock Polaris muffler just to remember how much quieter it was and to see how much power I would lose. Well, I ended up gaining alot of power down low and cannot notice a loss on the top end. Is this possible? Is it because to stock muffler produces more back pressure and gives me more torque? Is it because my jetting was off before and is right on for this set-up? I absolutely love the thing now. It's really quiet and just a quick tap of the throttle send the front end in the air!

 

I have an FMF pipe and sparkarester on my scrambler 400 4x4 and had the same problem. Went to the dunes with a friend who has the same quad all stock we drag raced a bunch of times with both mufflers. The only diffrence was with the FMF muffler on top it would just keep pulling slowly away until I let off, stock muffler we were dead even all the way through the power band. Thats my results for what Its worth.

 

it is not possible...the stock muffler is way too restrictive than a RCR
silencer,you may seen and improvment but was depending on jetting a lot
once the rcr silencer was on cayze it flow a lot more,so it may need richer jetting.
i run a RCR silencer,and this is the best i got for the 400 2 stroke til now,very lightweight,aluminum silencer,sound is throaty as hell,not too loud,fit well and look great,
but the most important it work!

 

Matt, I noticed my RCR silencer (I have that and Rick's midrange pipe) started getting a lot louder after several months of wide open riding. I called Rick to see about getting a quieter silencer and he told me that the one I have is fine, it just needs to be repacked. He told me to repack it with standard house insulation (after removing the backing of course). It is designed to allow you to remove the screws and slide the center out to repack and then put it back together. It will be much quieter after you are done.

I guess since it wears out over time, you really don't notice how much louder it gets.

 

[img]i/expressions/face-icon-small-smile.gif[/img]I have a RCR pipe and aluminum silencer as well. I also had the same problem recently(excessive noise). I bought the Silent Sport brand silencer packing and repacked it as tight as I could and reduced the noise by about 3 or 4 decibles. Now I can ride all day again without getting tired of hearing the machine running!! Just my 2cents worth.

 

Worn out packing will also hurt performance. You can use any kind of packing from any manufacturer. It is also a good idea to use a plug when washing to keep from damaging the packing with water. If you take care and don't get water in it, packing should last a few months of normal riding, If you were racing it is recommended to change about every other race and if you don't ride much at all, then at least once a year. Very cheap insurance to keep your machine peak. [img]i/expressions/face-icon-small-smile.gif[/img]

 

I have posted this before, so forgive me if it's old news. With a digital DB meter, I was able to cut 10 DB off the front of my pipe, and I think it was 4 or 5 off the rear. All this by adding the simple HPD quieting kit. One kit only has enough to do the pipe, so you'll have to get two in order to do the silencer also. Along with repacking, a great way to keep the neighbors happy. The meter is self-calibrating.

 

Personally, the sound doesn't bother me. I only have about 10 hours of riding time on the silencer, so I'm sure the packing is good. The people riding behind me were complaining about the noise. I'm more curious as to why I achieved more power with the stock muffler. Was my jetting that far off before? Now with the stock muffler, the jetting is closer to where it should be? Or, is the extra back pressure from the stock muffler giving me more low end power? I'm just trying to decide if I should keep the stock muffler on and leave it alone or if I should put the RCR muffler back on and richen my main to see if I get more power. I think I have a 260 or 280 main in now. How big should I go if I switch back to the RCR silencer?

 

270-280 with stock 34 carb is spot on with pipe,i think you should raise the needle 1 clip and tried it out and richen out a little the air screw
with RCR silencer.