Modified stock pipe saves big $$$

I'm in the middle of doing this mod right now. Having a time getting the 1st baffle out (one closest to the tail pipe.)

I bought this bike used... is this the stock tail pipe?

WR%20tailpipe.jpg

WR%20tailpipe2.jpg

Sorry to bring up such an old thread, but it's a good one. Most pipes are very expensive, if this will give me more power and a better sound, I'll be happy.

here's a clip of what the bike sounds like with the tail pipe and both baffles intact:

http://www.3.8mustang.com/justang/WR450/MVI_1486.AVI

Anybody know what Db this mod is running at? Michigan only lets 94Db on the trails (legally). I have removed the small insert in the tip, on my '06, much better sound and power. So far i have passed sound check. It runs at 94.8Db (barely passes).

My buddies '06 checked at 96.5 DB last summer with the first baffle drilled and the stock muffler tip enlarged to fit the outlet on the cone. Any more openings will probably put you over the limit. WR Dave

Done the mod last week end sounds great I can't go try it out due to 12+" of snow I would like to put a peforated pipe in with packing I just can't find the pipe any suggestions:ride:

:thumbsup:

Eh Dudes! I just did this baffle removement(rear Baf) with a cutting torch and large punch. I tried the drilling, way to much effort! Then I tried the torch on one of the weld's, as soon as the metal reached it's melting point "BANG" with the punch and hammer, the weld broke loose and on to the next. The torch worked great and what a clean job it made (10 minutes). Just to mention I have very little experiencewith welding equipment.

Also I left the tailpipe out. SHOULD I RE-JET ???

Also when I bought my 2005 wr450, it came with a 48pilot jet and another needle jet along with the manual. What size is this needle that comes with these bikes?????

Thanks for this post dude....I shead a tear when I read it....I just broke my can down and was about to put it back together and start cussin as the drillin holes or hole saw crap was lookin like a whole afternoon of work and buying more tools...gonna fire up the torch and make it happen.

I'm in the middle of doing this mod right now. Having a time getting the 1st baffle out (one closest to the tail pipe.)

I bought this bike used... is this the stock tail pipe?

WR%20tailpipe.jpg

WR%20tailpipe2.jpg

Sorry to bring up such an old thread, but it's a good one. Most pipes are very expensive, if this will give me more power and a better sound, I'll be happy.

here's a clip of what the bike sounds like with the tail pipe and both baffles intact:

http://www.3.8mustang.com/justang/WR450/MVI_1486.AVI

No that is NOT stock. That is a pro moto billet end cap.

OK for those of you that are reading through this old thread with anxiety about attempting to mod your can here is what I found during my go at it excluding the bolt off items.

1) Once I removed the bolts for the turndown and drilled the rivets to get the spark arrester mount out...I took a knife and sort of poked it between the can and the arrester mount then sprayed Hudini (WD40 Knockoff) where the knife was placed figuring I may get a little bit between the two. Went all the way around with it. Then I used my only feasible method for removal of the mount since I didn't have a puller or slide hammer. I call it the gripit-and-ripit tool and man it worked so damn good I had to applaude myself. Took one of my bikes tiedown straps and pulled the ratchet off so that I just had the strap with a hook on the end. I positioned the hook behind the arrester mount on what I could feel was reinforcement around the outer section beyond the bolt holes (get a finger dirty if you are trying this to see what I mean). Then I took the free end of the strap and wrapped it around the head of my framing hammer going through the claw after the last wrap...Then just keep one hand on the strap to maintain tension to the mount and swing away...3 good pulls in my case and out she popped. I was amazed how good it worked after all that I read concerning this mod so in celebration I had 2 beers.:thumbsup:

2) If you want to spend a few hours in a tight dirty hole go to the club and find a freak...do not waste time drilling into the baffle. Find a torch and do what gelean01 said do...torch each spot weld and use a long punch (I used rebar) to knock it loose. Takes no time at all and is a very clean solution to a dirty job.:eek:

Good luck

Heating up the outside edge of the muffler with a torch works great, too.

I did this and within weeks I went and got a Dr.D pipe. I had a hard time getting a consistent tune with this mod done. Put the Dr.D pipe on and no more problems. Do this mod at your own risk.

If you want to spend a few hours in a tight dirty hole go to the club and find a freak...

:thumbsup:

Who says its gonna be tight?

:confused:

Thanks for this post dude....I shead a tear when I read it....I just broke my can down and was about to put it back together and start cussin as the drillin holes or hole saw crap was lookin like a whole afternoon of work and buying more tools...gonna fire up the torch and make it happen.

I and my co-worker tried this way after reading the post, but did not work. We were unable to break the welds. We've only deformed the buffle, but welds stay strong.

My co-worker was fairly familiar with welding, and he didn't think we could do it in the first place, but we tried anyway. Now I'm stuck with badly deformed baffle(the one close to the tail).

I wonder how gelean01 were able to do that way.

OK. I tried again. The perforated wall inside the can just ripped instead of welds. Now I need to buy a new exhaust....

I should've done this a hard way(drill, chisel and a hammer).....

Ok, I'm new to these bikes and this forum so please tale it easy on me!!

In regard to stock muffler mods.....

I have made a tailpipe up for my '07 WR450F of 29mm ID. It just slips inside the tapered muffler end. I used a pipe bender to get a nice curve on it and it fits like a bought one.

Following the flow of gas in the pipe, each section has the following hole area (ie. the area that allows gas to flow.)

Header pipe: 43mm ID = 1,452mm squared

First baffle: 29mm ID = 661mm squared

Second baffle: 17mm + 20mm ID = 227mm squared + 314mm squared

(= total of 541mm squared.)

My new tail-pipe: 29mm ID = 661mm squared

I believe these bikes need a certain back pressure to make them run well and reliably. (ie. I'm not chasing that 43mm right through to the tail-pipe.)

My intention is to modify that second baffle to bring it up to the same hole area as both the first baffle and tail-pipe.

All this means (mathematically) is a simple 6.2mm diameter hole drilled in it.

Ok, I'll use a 1/4" drill (6.4mm diameter) to make sure.

I figure I'll get more power everywhere (the combination of the new tail-pipe and 6.4mm hole), yet the bike will hopefully remain reasonably quiet too.

Thoughts / input anyone?

Cheers,

Greg

PS. I've bought a JD jetting kit and intend to install that before I ride the bike in anger just in case it's now a bit lean.

That's similar to what I did on my '07 as well, I made a tailpipe that required the endcap to be opened up slightly, then with the spark arrestor out I took a very long 3/8" drill bit and drilled 3 holes straight through the muffler down into the first chamber. The bike is definetly louder than stock and has much better power , but it is nowhere near as loud as a stock YZ or the DrD pipe that I heard at the track the other day. I am still running the bike with the spark arrestor in place. Money saved in my opinion to be spent in other areas. WR Dave

What I did was remove all the baffles and put in a perforated pipe with packing and made another baffle for the perforated pipe to sit in and still retained the sparky and used a bigger tail pipe. The bike runs very well now:thumbsup:

flynz,

I must admit I thought along those lines myself.

Is it much louder now?

That's my biggest concern.

Greg

Yes it is louder than stock but much quieter than without the perf and packing I think I'm still quieter than the race bikes haven't put a meter to it so I don't know what the db levels are.

My intention is to modify that second baffle to bring it up to the same hole area as both the first baffle and tail-pipe.

All this means (mathematically) is a simple 6.2mm diameter hole drilled in it.

Ok, I'll use a 1/4" drill (6.4mm diameter) to make sure.

I figure I'll get more power everywhere (the combination of the new tail-pipe and 6.4mm hole), yet the bike will hopefully remain reasonably quiet too.

I just noticed that I made a slight mathematical mistake...

6.2mm is the radius required, so therefore it's a 12.4mm diameter hole that is required (twice the radius gives the diameter!) to be drilled in that second baffle :thumbsup:

In other words, use a half inch drill bit to drill the hole!

This is my home-made 31.8OD x 29mm ID insert:

wr450-250f_exhaust_insert_1.jpg

wr450-250f_exhaust_insert_2.jpg

wr450-250f_exhaust_insert_3.jpg

wr450-250f_exhaust_insert_4.jpg

Greg

you guys are working way too hard

just buy a used yz silencer. By the time you are done the stock YZ pipe would probably be quieter too

just buy a used yz silencer. By the time you are done the stock YZ pipe would probably be quieter too

Fair call.

Trouble is (for me) I love making/modifying stuff....... it's a disease I have never managed to shake!

I reckon if someone gave me a YZ450F muffler i'd still want to modify my WR450F one! :thumbsup:

Greg

But the yz pipe has no sparky thus we modify ours for more performance

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