just got done tuning my carbs.... (semi-long)

[Anonymous]

Last summer, I put K&N's, a 4-1 and a Dynojet Stage 3 jet kit, and everything seemed alright, but - I never really rode very far, just around town (my SMALL hometown). Also, at the beginning of this year, I replaced the standard baffle in my MAC exhaust system with a competition (read: straight through) baffle. Surprisingly, it was not a whole lot louder, but it seemed to have a little more bite, although it would only pull to about 9000 rpm before running out of steam (indicated redline on my tach is 10k), so I knew I needed some more fuel on the top end. Fast forward to this school year; I brought the bike with me to ride around campus (much easier to park, cheaper, and more fun than my car) and noticed on the longer rides it is now subjected to, it didn't seem to idle as well and would occasionally die at idle, which I figured had to be a rich problem, since as the engine heats up, air expands = less oxygen/more fuel = not running as well.

Anyway, tonight I took it to the shop at work (I am a golf course mechanic, and have legitimate access to a nice clean shop), put the bigger main jets in that came in my jet kit (DJ 155 vs the DJ150's I was running vs the Mikuni 92.5s that were in it when I started) and also backed out the idle mix screw another half turn since it appeared to control airflow, not fuel flow. Put everything back together, take it for a ride, drop the clutch at about 5k, and presto a burning out power-wheelie take off (oops!) :twisted: and even better, it starts and idles magically, even when warm, and will pull to 10000 rpm, although it still seems a little short above 9500, so I've made that my official shift point. Well, that's my story. I'm done. I just thought I would share.

 

[Anonymous]

maybe the mack exhausts are under rated-All I have ever heard about them is that they are designed for no necessary to change jetting type mods. i have a cpmpeition baffel for my star headder and its abouyt as much of a baffel as a straight pipe however it does deepen the tone of the megaphone and give me just enough back pressure to notice it on the bottom end.
Im saying this because i am interested in knowing about the design of the Mack competition baffel if you care to describe it to me

 

[Anonymous]

competition baffle

competition baffle

Originally, the jetting wasn't so much to compensate for the exhaust as the airbox removal. The standard mac baffle looks like this:

The competition baffle looks like this:

It is just a 1.5" straight-thru core. It made a noticable difference over the standard baffle when I put it in.

My feelings on the mac system are: it is not the highest quality or most well engineered exhaust system in the world, but neither is it terribly expensive, and it was the only system I could find that fit my bike. I would say that I have been satisfied with it.

 

[Anonymous]

That original baffel looks like it would choke a moped for air and the competition baffel is a riot because eit doesnt baffel anything--its my kind of baffel- it is obvious thatthe engine should run diferently with the open baffel