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Discussion Starter #1
hello

i'm in the putting-back-together phase of some maintenance on my '90. i've had it for about 6 years, 3rd owner, 12,000 pretty easy kms. this is probably the only maintenance it's gotten really.

engine side cover off, new filters, new sprockets and o-ring chain, clean out the disintegrated foam air filter from the air box, clean up carb, paint touch up on frame, new front brake cable, petcock overhaul, inspect and fluid-film all electrical connectors,

and, discovered that the stock muffler had become a rusted-hollow shell. after a day to split the exhaust, and after several days of researching tw200 exhaust stuff (discovered this site, has been very helpful) and locally pricing a replacement stock muffler at ~$350 cdn, i decided to rebuild the guts on the stock. it's only sheet metal.

i don't want a aftermarket muffler; similar cost (or more), and as someone on this forum stated (sorry i didn't copy the links);

Qwerty posted this fine bit of advice a few years ago....

"Note that Yamaha engineers put significant work into using sound and pressure reversions to work to widen the TW's powerband, and some cost of peak horsepower. That is why TWs are as torquey as they are for a 9,500rpm engine. Though aftermarket exhausts might, in some cases, actually add a fraction of a peak horsepower, or maybe a lb/ft or two of torque, virtually none can match the stock exhaust for its broad torque curve at the same peak horsepower on a stock or lightly modified engine. If I'm wrong, post actual dyno results and prove it. Be aware that if you ride offroad where approved spark arrestors are required, an aftermarket exhaust can be cause to have your bike confiscated.

However, there are many valid reasons for aftermarket exhausts. Looks, sound, weight savings, and torque curve manipulation, especially with highly modified engines, are all good reasons to go aftermarket."

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so here is what i have figured out so far in terms of rebuilding the guts of the stock muffler.
there are a few measurements and views missing, if someone could figure out those from an intact-ish muffler and add them in here, that would be great!


tw_exh_bits.JPG
this is what is was left of mine. exterior is all good other than a few pinholes along the bottom i will weld up with the torch. the tube to the left fits into the muffler and then the spark arrestor slides into that. the tube sits kinda in that orientation, the oblong hole up/rear. don't know if there were holes in the front/bottom of the tube as it's rusted gone but i don't think so.

tw_exh_int.JPG
there was a baffle half way up the length of the muffler, you can see where it was welded to the wall in this photo. note also the patch of dense padding stuck to the wall upper right just past the "blue line".

tw_exh_silencer.png
this is what the shaft of the spark arrester looks like.
from http://tw200forum.com/forum/technical-help/10251-end-cap-my-muffler.html


tw_exh_drawing1.jpg

this is the original design as far as i can tell.

i can figure out how to rebuild the spark arrester/endcap, but i need some help in regards to the main tube and the baffle.

my questions are:

1) how long is the tube

2) is the deep end blocked off, open, partly baffled?
i assume open, given the twirly fins on the end of the spark arrester.

3) what is the baffle like? solid, partial, holes, padded?
(either a dental mirror, or a wire bent into a "J" to reach up the tube and tap the baffle from the primary chamber side ).

4) is there packing in the secondary chamber?

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any help appreciated. will post progress.

slowmod


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also of interest:
Home made exhaust - Yamaha TW200 Trailway Discussion Forum
build yer own muffler

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Discussion Starter #2
i'm not set up for ebay, another $40 to ship to canada ... thanks for the link though.
 
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