Bonneville America Forums Forums Technical Forums Exhaust Stock Baffle Knockout?

This past weekend I became quite bored, and curiosity got the best of me. I thought it would be a good idea to remove the furthermost rear baffle on my 03' America's exhaust. It did get louder, but definitely also demonstrated more of a tendency to pop and crackle on deceleration. I ordered an AI kit to heep with this problem, but will this do the trick? Actually the popping and the crackle, despite being a bit bothersome, are doable. The thing I am concerned with is potential discoloration of the header pipes. Has anyone out there had a problem with header discoloration after knocking out stock baffles? I know a few on this forum have knocked out two baffles on the stock exhaust. Will this discolor the headers at all without a rejet (which I am quite squeamish about performing myself)? I know that knocking out the baffles causes the bike to run leaner and thus hotter, which can cause the headers to score. At what point do I need to be concerned about hurting the chrome on the headers, and if the bike does run leaner (and hotter), will this hurt the bike? All comments are welcome! Cheers!

Monkey boy,
You will need to adjust your air screws (Pilot screws is the real name) on the carbs once you knock out the AI to get rid of the decel popping. Check my site for destructions. Don't be a girl, it's easy enough to rejet these bikes. Even a chimp can do it.

Chimp,
I don't think baffle removal will have any direct effect on pipe discoloration. I believe all discoloration is the product of excessive heat in the header pipe. As Pat alludes, the AI is considered the primary source of that heat because of how it functions. I've removed two baffles without a problem w/ discoloration. My AI is still in place w/ 8500 miles on the clock. My carbs are set w/ standard jetting and were tuned when I installed a set of short off-roads soon after purchase. When I re-installed a set of SM silencers w/ the baffles removed, I made no change to jets or screw settings. Approximately 2000 on my miles are with these altered SM silencers. In short, performance changes may result from changes in baffles, but I don't feel bluing will result - Theoretically, the removal of some restriction may actually reduce heat build-up in the header (?), but initial exhaust heat at the header, IMO, is the result of improper carb settings or jetting in conjunction with the AI. AI removal is probably the cheapest, easiest solution to bluing problems - However, since the AI is a designed component, my feeling is the root cause is improper carb settings regardless of whether the AI is in place or removed. I hope that muddies the water for you...

Oh, and by the way - I know a guy who uses the same primate moniker - He's a furry *******. I hope you don't have the same affliction.

Barry

Nope, no affliction here.

I think I may remove another baffle if heat is not an issue - the first one still keeps it too quiet. I'll install that AI kit, and retune the pilot screws if that is all it takes to get rid of the popping. Eventually I may do a rejet, once I install "the freak", but I'm going to wait until then.

Pipedr, did taking out the second baffle make it significantly louder? I put on a pair of really cheap JCW shorties, and they were deafening (although I do admit to having a grin on my face whilst going deaf). I didn't feel any adverse effects on performance. In fact, the bike seemed more responsive with the shorties on. But alas, it was just too loud, and there wasn't enough room to put another baffle in them. I'm trying to get a grumbly sound out of the bike but not abnoxious without buying all new pipes. Any suggestions?

Cheers!

Jeez, Pat. The poor primate posts his first and you go bust his nads!!

Josh, read between Pat's lines here and btw, the link to his site is:

http://members.bluefrog.com/~pwhitbec/index.html

Even though he's a hard headed SOB, he does have SOME useful info there!

Thanks guys! Pat, the website is great! I may try and assemble a set of speedy pipes like yours. Did it take a long time? Without rejetting, would the bike run fine after installing them? Thanks in advance!

The Chimp

Oh, and I just posted another question about putting another baffle in those cheap JCW pipes. Any thoughts on that? Those guys are just too loud for my ears right now. Would adding another baffle work? Could I add more packing to the original baffle to help the cause?

The Chimp

Chimpy,
It didn't take long to mod the pipes. About an hour to cut off and gut them. Then about another hour to drive to the muffler shop while he made the baffle holders, another hour drinking and watching Steve weld for me. Back on and away I go.
I actually sold these pipes to member Rabun (whereever he went) awhile ago and he loved them. They were pretty loud and defenitely would "like" a rejet if this is done to stockers. The biggest trick was getting the backpressure to balance so the power was uniform.

Thanks Dinqua! Good to know.

I don't know about the difference between 1 and 2 baffle removal because I did them both at the same time. From my own perspective, two baffles removed from stock pipes is about equal to the loudness of the short TORs (Triumph Off-Road) I think the tone/sound is better- but that's a matter of opinion also. Initially, I based my decision on how many baffles to remove on the distance of the last/rear-most remaining baffle to the distance of the last baffle of the TOR silencer. The result was that there was no noticeable performance difference. I believe the tone difference is due to the remaining open chamber left where the baffles were as opposed to the soud emmiting directly out the last baffle of the TORs. Although many will disagree, I have heard NOTHING in after-market pipes/silencers that approaches the sound of the Triumphs of yore (the J.C. Whitneys seem to my ear to be the closest). I always wanted to get a set to play with but was reluctant because I've never enjoyed playing with carbs.

The "Triumphs of yore.." had a much different note due to the lower pitch (one octave) of pipes without a crossover....when the 750's came out, with their crossover pipe, the low note of the 650 was forever gone....give me a 650 Triumph or BSA exhaust note any day....

I generally agree, but, I've run her without silencers and the sound is pretty close. The noise level is unbearable but the sound is close.

Hey Chimp,

(Up near Duluth) I took out the last baffle and drilled 3 1/2 holes in the second. I love the tone and sound. Plugs are the best check on air issues as Pat's page will let you know. I found that after I modified my snorkle (much like taking the choke off) color of plugs improved. They never were real lean, but like you I was a bit worried about damaging my bike. It's working sweet now and plugs look good.

ed

I took out every baffle in my stock pipes and it sounds pretty good but it pops real bad on the down rev. I took the snorkel off the top of the aircleaner and it actually got a bit better.. I ordered the Air injection delete kit already, now What else can I do to reduce the pops??? thanks

I took out out the last baffle using a hole saw like Mikesr suggested. There was a post about a month ago on this. As someone else suggested instead of taking out the second baffle if you drill a hole in it, the sound will increase. You keep road testing till you get the sound level you want.
I put 3 holes in each baffle. I get the popping on decel but I don't see that as a problem.

Tomstrump - you need to adjust your pilot screws. Wind them 3 turns out to start with, and make minor adjustments from there. Much more info on Dinqua's excellent site:
http://members.bluefrog.com/~pwhitbec/Triumph/carbs10.html

I have the rear baffle out and 4 holes in the second. AI gone. I backed the pilots out to 3 turns and the decel popping went away completely. A carb sync thrown in for good measure is also a good idea. Don't count on them being in sync from the factory.

Well I took out my airbox and cut out the bottom of the filter then cout a hole on the bottom of the box and put a screen there, I also cut out the wall in the airbox and when i was done the poping cut in half. Then today i got my air injection delete in the mail and put that in and now there no pop at all. It sounds awsome, and its super loud... The best part is I have $31 dollors into the bike. oh and not to mention its 7 days old lol...