Ok, I took the pipe off the ATV and I cut the end off the pipe. I have drilled (7) 7/16" holes through all baffles (used and 18" drill bit). MY QUESTION, do I have to cut out the silencer/ baffle in the end cap? What is the spark arrester function on this? I am thinking of having a stainless steel cap welded on and having a bolt on opening, but will I get busted for not having the spark arrestor? Should I just leave the baffle as is and weld it back on? Will this give me a power increase still? Please help guys, I need to get this done today and drop it off at my buddys shop to have it welded back on and powder coated red!

 

Scooter

I cut out the baffle which went from 3/4 in to 1 1/2 in around unfortuneatly it gets rid of the spark arrestor. Another thing you can do is go to White Bros web site and order the end cap from them which will come with a spark arrestor and plates to make it sound quieter, it will fit in the end of the muffler with some moddification.

 

Thanks alltoys, I knew someone would come through. Since I have a big spark arrestor issue here in Colorado, I decided to not cut the baffle out. I am sure I won't see the 9% gains, but hopefully something close. I dropped it off at my buddys tonight and he will weld the end back on a powder it red or yellow for me tomorrow. Should be able to get it back on tomorrow night, change the jets (move the 142 to the front, put the new 145 in the rear, right?) and be ready to ride on Saturday!'

I will give you a full report on Monday, thanks again for all of your advice.

 

Sounds great let me know how it works, the jets with the intake modds will help above all have fun.

 

As far as I can tell, the glass pack tip has very little, if anything at all to do with spark arresting.

Each muffler is sent to a USFS testing lab to be certified. I guess they shoot sparky air through it and see how many can still exit. Sparks are stopped (before they would normally air cool) by contacing something much less hot which causes them to cool down and stop being sparks. This appears to be done most often by redirecting the exhaust flow path through the muffler (i.e. baffle plates), or by using a fine screen, or by making the exhaust flow through narrow gaps between plates (i.e. tuneable exhausts with plates).

Drilling holes through your pipe may or may not let sparks out. It would have to be tested and re-certified to be sure. Removing the glass packing on the tip has very, very little to do with eliminating sparks, other than it is slightly turned down and may inhibit a small percentage of sparks. It is still an alteration.

Altering your muffler technically voids the USFS certification. However, how does anyone really know you modified it?

The forest service officials "poke" a rod or wire into your muffler to see if the wire can go through the muffler without being stopped (by a screen or baffle). Therefore, opening the tip up won't have any affect on what the officials find. Drilling down the center is the worst thing you could do, since it would be easy to poke a wire down. Only drilling down the sides may be safer, since it would be really hard to get a stiff wire to go down the hole when you do not have a straight shot. I don't know for sure if this is sufficient.

Anyway, if you think you can survive the "muffler probe", you might not get cited. However, I am not suggesting you rely on a questionably safe system, especially in areas where there is greater fire danger.


Please feel free to shoot holes in what I have just said since I wanna make sure it is right before I post it somewhere more permanent. Anybody?

 

Thanks for the very lawyer like answer Nyroc. I decided against cutting it out, call me a puss, but I figured I will get some gain from it, I am only waiting for the cashflow to get an aftermarket one, and to decide on one, so I figured this was free, lets do it. I did drill one hole right down the middle, oh well. It is back on and sounds great. Not much of a noise change, except from behind it, there is definitely more air coming out! I have not tested it yet, waiting for the weekend. I am sure I will be happy, I am quite easy to please, but extremely inquisitive!

Thanks to Alltoys and Nyroc for your patience and help, this is fun more than anything! Ride on!!!

 

Someone told me that technically you could get a citation for having modified the stock muffler.

I don't know for sure whether the rod poking applies or if they look for mods. Some say this, some say that.

I am interested in a Q series from fmf. Supposed to be quiet. I don't need to be the fastest. I'm content to let alltoys be the fastest.

 

OOOOO, come on, show me the pic! Can you email it to me Nyroc? That is something that I am very interested in, sounds like a good way to go about it. I am not sure on the prying eyes either, but if the end cap is a spark arresting tuneable type....

 

It is in my "Prairie 650 Exhaust Modification" tech tip.

 

I know this is the Kawasaki forum BUT has anyone done this mod to a Grizz yet? I'm thinking of trying it but the Grizz is pretty loud stock and I do use it for hunting. Does this mod require rejetting?