Topic: Slip ons + baffle = no rejet ?

[Anti-Johnny]

If I order something like this,

http://www.amazon.com/Emgo-Shorty-Universal-Motorcycle-Muffler/dp/B003NQAJPY

Would I need to rejet my carbs?  I dont think they have baffles in them, but JCWhitney sells some that might fit it, or I could try to make some to get the back pressure. I just dont want to mess with the carbs at this point.

Thanks fellas. And happy thanksgiving

[KingCustomCycles.com]

I have used many of those "mufflers" and they do not have baffles.  There is a removeable screen and tube but you can look through them like a telescope.  I am not sure if a baffle is available off the shelf but they can be fabricated easily out of steel tube with discs welded to the ends.  The existing baffle could be modified.  Experiment with the number of holes to get the sound and back pressure you want.  Another option would be a restrictor plate inserted at the front of the muffler as you install it, or at the rear held in with the existing baffle bolt.  I did not have to rejet my CB400T Cafe with the mufflers as they came from cycle recycle 2 and the stock airbox, what a nice sound.  

[Hondawggie]

You can install the slip-on then check the spark plugs. 

The center ceramic on the plug has a golden-brown look when the bike's jetting is fine and the top of the plug has the same appearance.


After you install the slip-on and give it a good run, if your plugs look very white and dry, they are getting too hot and you're running lean.   If they still look golden-brown then you're okay.

However, if you like to tinker, since most bikes are jetted on the lean side for emissions requirements, you could increase the main jet a couple sizes after the slip-on's installed.

Is your airbox 100% stock?

[Anti-Johnny]

Thanks for the advice.

yeah stock airbox. This is my second bike, but first where I have been concerned with learning about the workings of it. Just not ready to dig into rejetting.

[Anti-Johnny]

I have another quick question before I order these, they are the same from cycle recycle by the way. The diameter on the site says they fit 1.5 or 1.75 in pipes. I dont know what mine are exactly but with a measuring tape, its definitely bigger in diameter than either of those sizes. can this measurement possibly be something else other than diameter? because 1.5 seems pretty small.

[KingCustomCycles.com]

They are small, but so are the header pipes. If you have a 2-1 set-up on each side (MAC) then they will need an adapter.  The upside of that is the restriction will take care of your back pressure even with the stock see through baffle. 

[dave500]

run them or any similar and itll lean out a little,ok if you dont fang highways at high revs for any long time,id lift the needle one notch for saftey if you do stay in the higher rev range.if you lift the needle itll need a resync as the balance settings will be disturbed.


heres a proper straight through muffler(resonator) with a reducer installed,this adds some back pressure and takes the drone out of it,i for one care less for appearance when it comes to exhausts,they have to function,most of these cheap bike ones only look the part and have chrome,or a good looking decal.

[Anti-Johnny]

Found this for sale on another site that offered better pictures. I am still on the fence about it, might just save up for a 4-1.


Just posting this in case anyone comes across this thread and needs a visual.

http://www.dimecitycycles.com/media/catalog/product/cache/1//5e06319eda06f020e43594a9c230972d/8/0/80-03310-vintage-cafe-racer-caferacer-bobber-brat-chopper-streetfighter-motorcycle-parts-shorty-muffler-close2.jpg

http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-streetfighter-motorcycle-parts-12-inch-shorty-muffler-80-03310.html