Cut and modify the stock Citycom exhaust muffler?

[Thoppa]

Hi,

Has anyone tried to cut and modify the stock Citycom exhaust muffler, or a similar design? I have done a lot of Googling but not found any pictures of the innards to see the inside routing design. I only found this post by Doug Reid so far http://symforum.com/index.php?topic=985.msg5814#msg5814

I can see the exit pipe has a curve inside - so I can't see how long or how deep inside the muffler it goes. I put a very long cable tie down the pipe and then pulled the tie out until it caught on the end of the pipe. It seems it 27.5 cm long.

I can also see a mesh on the inlet pipe and measured that as 15cm from the front of the inlet. I assume that mesh is the start of the cat.

The whole muffler is 61cm. I'm guessing it is like the design of the Zuma or the Honda Faze 250 ?

What I'd like to do is keep the cat for environmental reasons, but improve the gas flow by losing or widening some of the interior chambers/piping. I already have an aftermarket pipe so the stock muffler is not in use. Something like this:



Any thoughts anyone? Do you know anyone that has done a successful mod?

All the best,

EDIT - just seen a cheap after market exhaust on Ebay. http://www.ebay.co.uk/itm/201501946680?_trksid=p2060353.m1438.l2649&var=500683017960&ssPageName=STRK%3AMEBIDX%3AIT
Looks interesting...

[soulysephiroth]

I've got the dominator on my sym. It's a great sound. Takes weight off the back end. Doesn't seem to help much on gas millage.

[Thoppa]

Cool - how long have you had it? Is it good quality? I'm also wondering if it makes a lot of noise or has made the engine run leaner - the spark plug won't be as brown/black as before.

I'm trying out a new exhaust too - a longer one designed for a CB400. Works better than the short one. So far so good.

All the best,
Tom

[soulysephiroth]

I've removed the decibel killer, and its makes quite a bit of noise for a scooter. I wanted it to make it sound better for more visibility. I haven't checked my spark plug, but like I said, I don't seem to notice much change in gas mileage, and since I'm only on about 1010miles on it right now, its just starting to get fully broken in. Been using it for a few months now, and its great. I noticed that it pops sometimes, which I never had issues with on the stock.

[Thoppa]

Mikuni's page about pops is pretty darned good for carb bikes. With FI bikes, the system is closed so it can adapt to small changes, but not to large changes, so the mixture needs to go richer by tricking or modifying the system.  You can get the FI set richer by taking it to a SYM dealer and they can plug in the handheld monitor. The monitor also allows them to change the FI a little. http://www.mikuni.com/tg_backfires_in_exhaust.html