Drz400 Thread

[One Less Harley]

The FMF Q4 (about $288) is not a straight through muffler, and should bolt right up to an E or S/SM head pipe. A good chance it'll bolt up to you existing FMF header. It's pretty quiet with the spark arrestor and a little louder (deep) with out it. Lighter and a wee bit shorter than st stock can.

[Mike_drz]

when you need some torque, roll on throttle it gives very robust sound too. I am very happy with the 496 system

[955616846]

Originally Posted by One Less Harley

The FMF Q4 (about $288) is not a straight through muffler, and should bolt right up to an E or S/SM head pipe. A good chance it'll bolt up to you existing FMF header. It's pretty quiet with the spark arrestor and a little louder (deep) with out it. Lighter and a wee bit shorter than st stock can.

They still have a habit of blowing the end off the can.

[buls4evr]

Originally Posted by 955616846

Just about every OTHER aftermarket exhaust is a straight through design which will never make it down to acceptable noise levels without throwing away its number one benefit and causing other problems like the one that you have already experienced. Tuning a muffler to the primary exhaust pulse frequencies of a thumper is a difficult task. More often than not noise requirements are met at the expense of back pressure which when combined with a strong primary pulse can quite literally tear a lightly built muffler apart.

My suggestion... The Suzuki 35F0 from an 01-02-ish GSX-R 600/750 is a quality built muffler that flows well, has an acceptable noise level (I too like civilised noise levels) with a little thumper character. These are louder than stock, but quieter than FMF, won't blow out (typical FMF, but they're not alone here) and doesn't need repacking.

The downside is that at 120mm diameter ( length is 450mm + tip btw) it is quite a large muffler although only slightly larger than the late model OEM DR-Z mufflers with the tapered tip... much larger than the FMF. It will need a flange (+ gasket), a new or modified link pipe which your local exhaust shop should be able to build plus either a new mounting lug welded to the sub-frame (recommended) or a relocation bracket.

It is not only huge....but has no spark arrestor! Useless for all but street use in the states. My buddy has one on his DR650. Biggest problem is no one builds a SA for it. It does make nice power though. A lot louder than stock also.

[One Less Harley]

Originally Posted by 955616846

They still have a habit of blowing the end off the can.

Are you talking about the Q4 or another FMF as I don't see how the end can blow off with the four rivets around the side holding it in place. If someone has taken it apart and not used long enough rivets then maybe.

Four rivets to hold cap in place , I doubt the end cap has slotted holes for the rivets which could allow the cap to blow off.



Inner Baffle, one could drill out the holes a little for more flow.



Spark Arrestor-

[955616846]

Originally Posted by One Less Harley

Are you talking about the Q4 or another FMF as I don't see how the end can blow off with the four rivets around the side holding it in place. If someone has taken it apart and not used long enough rivets then maybe.

Four rivets to hold cap in place , I doubt the end cap has slotted holes for the rivets which could allow the cap to blow off.

Definitely the Q4. I am not sure what you're talking about. The failures sighted have occurred within a couple of inches of the end cap

[bobbed06]

Originally Posted by The Recycled Teenager

Is that sucker plastic
Why the heck would they make out out of anything but metal

I know the answer will be forthcoming from some quarter of the planet

OH! and how many kilometers/miles are on it ????

Yep plastic, there was talk of someone making a metal gear but they rarely fail so it never happened. Usually it gets damaged during the clutch basket install then fails due to this.

[One Less Harley]

You said "They still have a habit of blowing the end off the can." which makes me think end cap.

then you said "The failures sighted have occurred within a couple of inches of the end cap " which makes me think internal baffles??

We are talking about DRZ mufflers too right?? Care to be more specific on the failure? As I not sure to what your referring. Pictures would be good.

[955616846]

Originally Posted by buls4evr

It is not only huge....but has no spark arrestor! Useless for all but street use in the states. My buddy has one on his DR650. Biggest problem is no one builds a SA for it. It does make nice power though. A lot louder than stock also.

What exactly does your buddy have? The popular choice for the DR is the 40F0 or 45F0 and I am fairly certain that the spark arrestor problem was solved for the 40F0.

The 35F0 on mine came in under 93dB (SNT @ 0.5m 45 deg and 4000rpm) while the Q4 blew over 94dB under the same conditions (an instant fail for the DR-Z in these parts btw), but on a different bike. Stock is 89dB.

Huge is a relative term. In comparison to my stock 2011 muffler it is less than ~3/8" larger in diameter and the tip is located a couple of inches further back... not so huge. Some of the popular mufflers for the DR-Z which measure less than 4" in diameter I can only describe as tiny... and worthless in terms of their ability to suppress noise.

[955616846]

Originally Posted by One Less Harley

You said "They still have a habit of blowing the end off the can." which makes me think end cap.

then you said "The failures sighted have occurred within a couple of inches of the end cap " which makes me think internal baffles??

We are talking about DRZ mufflers too right?? Care to be more specific on the failure? As I not sure to what your referring. Pictures would be good.

Gaah!

Yes, they were DR-Zs one of which was used for sound level comparisons. Failures were similar enough in outward appearance to other FMF failures. They weren't my bikes and I didn't care enough to take pictures nor did I care enough to examine the mufflers in minute detail - many would, l don't. The cans had failed, that was all that I needed to know and all that I was saying.

[blaster11]

So here are the pictures of the muffler with the endcap blown off. As you can see it's an older round muffler that had the cap secured with allen head screws. The other end of the muffler has allen head screws securing it as well and not rivets.





Another guy I know has a Muzzy system, haven't heard it in person, on his bike and believes it is quieter than the FMF...anyone runing a Muzzy and have any thoughts

[One Less Harley]

Originally Posted by 955616846

Gaah!

Failures were similar enough in outward appearance to other FMF failures.

The cans had failed, that was all that I needed to know and all that I was saying.

I was curious to what you had seen as I am not familiar with FMF failures (where?). From your post I still don't know where the muffler failed.


Thanks for the pict Blaster. There's a lot of vibes from the DRZ I can see how the screws might break or back out. That's repairable if one can find the endcap.

Guess we will see if the oval style still fails. I did see a post w/ a WR 450 which split the housing in half and blew it off the end. The fracture started at the riveted on top mounting bracket then continued around the housing till it blew off. Is this what you saw??? Since the DRZ doesn't have the same mounting this shouldn't be an issue.

[Starchamp]

Originally Posted by blaster11

So here are the pictures of the muffler with the endcap blown off. As you can see it's an older round muffler that had the cap secured with allen head screws. The other end of the muffler has allen head screws securing it as well and not rivets.

This is a two-piece endcap, just like my Yoshi RS2. The part that is missing is held on by three allen-head bolts (see holes above), and is made to be removable so you can take the spark arrestor out when/if it's not needed. There's nothing wrong with this muffler, with the possible exception of the threads being stripped (which is easily fixable, in a number of different ways). You can probably find a replacement tip (and SA) on ebay (perhaps http://www.ebay.com/itm/FMF-Racing-Q...a17af4&vxp=mtr ?), if FMF doesn't stock them anymore. Find that piece, give it a repack, and it'll be good to go.

Of course, if someone is just looking for a reason to upgrade, then of course it's FUBAR.

[Mike_drz]

got around 51.45 mpg last night's city dash



___________
catch me if you can

[955616846]

Originally Posted by One Less Harley

Guess we will see if the oval style still fails. I did see a post w/ a WR 450 which split the housing in half and blew it off the end. The fracture started at the riveted on top mounting bracket then continued around the housing till it blew off. Is this what you saw??? Since the DRZ doesn't have the same mounting this shouldn't be an issue.

Similar to that photo although nearer the end of the can.