Bonneville America Forums Forums Technical Forums Exhaust Bubs without baffles

I took the baffles out of my bubs. I'm one of those obnoxious people that really love the sound of a loud machine. Well... Its loud now! Almost painfully loud. With the baffles (Which were nothing but a long tube of corrugated metal) they seemed like they were too quiet for my taste, but now I'm actually wondering whether or not I've overdone it.

My delimma is two-fold. One, is there a way to tone them down just a little bit? like say maybe cutting the length of tubing on the baffle and then reinserting them using the old rivet holes?

And the second part of the delimma is whether or not missing the back pressure created by the baffles is going to be a problem with regards to harming the engine. I had it re-jetted when I had the pipes installed initially, but wonder if I should do it again after having taken out the baffles. I'm afraid of running it too rich and harming the engine that way as well (but don't really want to spend the money on doing it right now if I don't have to).

There's very little backfire, but some popping on decel. The popping is not very loud, but I was concerned that it may be sucking cold air back into the engine (which I'm told is not good).

So any thoughts on the subject would be appreciated! I know some of you have mucho experienco when it comes to pipes and baffles, so would appreciate the feedback.

WHAT?

WHAAAAT? WHAT DID HE SAY?!!!

well you do need back pressure for low end torque and the valves slam shut a little harder with no back pressure. In the long term could beat up the valve seats. Doesn't take much the reducer cone in the stock pipes is what I leave in. You could use one of the small baffles at J&P cycles among many other places. Basicly a 4" tube that looks like someone used a can opener on the sides of.That won't effect the sound much,if you want to quiet it down why not weld some nuts on the baffles you have so you can remove it and experiment with different amounts of packing or trim a little off it at a time until you have what you want.

A set of the 4" baffles can be had on ebay for $9 total from shotglassx83. I've bought 4 sets of them from him. I usually get them in two days!

Anyway- running rich doesn't harm the engine, it just wastes fuel. There is a finite amount of O2 to mix the fuel with. anything above 14.6:1 just fouls plugs and goes out the pipes. Running lean, on the other hand, will harm the engine (i.e. burnt valves).

Dogg is spot on about the back pressure causing a loss of low end torque. You need some. I've got some BUB's, a set of fishtails, had D&D, have a set of Khromewerks short $30 turn-outs, and have had a set of JCW turn-outs, as well a a few sets of stock pipes in varying stages of de-baffle up to and including a set that are nothing but the cans- so I have experimented with pipes and baffle quite a bit.

My experience with the open totally dissected (baffles, screens, packing, reducers,- everything) would be identical to your gutted BUB's. I put one of the 4" baffles in the header and ran them like that for a couple of days. Still silly loud, and the tone is not good. Still has that hollow ringing metal sound. Also, the BUB's out perform that setup. If you are going for performance, the stock BUB's will be hard to beat. They are designed for that bike.

You might try some things. Nothing has performed as well as the BUB's on my bike, purely from a performance standpoint. But, I don't care for the looks of them. I REALLY like my fishtails, and have spent hours trying to tune them to perform like the BUB's. I have two sets of the 4" baffles in each side; one at the end of a 22" straight extension piece and another at the exit of the 'tails. At first it was way too much. No power at all. So, after much experimenting (remove the front set, turn the front set around, cut the front set in half and try it both ways, open the center up, etc.) I ended up with two in each side, but ran a 3/8 stick of rebar through them to "open them up". Seems to be close to the BUB's now. A little less low end but a bit more "snap" on the freeway. Has a nice sold idle note and will still give off that fishtail "crack" when you hit it.

I'd try the 4" baffle or maybe the 8" and cut it off (8" won't fit up the header, only about 6" will). I like the beer can baffles better than the stock reducers, even if you run them straight. Just cut the flaps off and you now have a high flow reducer!

Not exactly true,slightly rich Coiwtipper is right it won't hurt anything except a little extra carbon build up. But if it is too rich the extra fuel will wash away lubrication and contaminate the oil causing early failure and excessive wear.

If you do as Cowtipper suggests you basicly have a reducer cone and I think that is probably what you want. Won't do much for the loudness though if you are after a quieter pipe.

(me)...But if it is too rich the extra fuel will wash away lubrication and contaminate the oil causing early failure and excessive wear...

(Cowtipper) Yes, you are correct, but doesn't that have to be waayyyy rich? Can you smell it in the oil at that point?

(me)Yes it has has be pretty rich for it to have that effect and you should be able to smell it in the oil at that point. To effect the lubrication of the rings to cyl. wall it doesn't have to be righ enough to smell it in the oil but you should be able to smell the unburned gas in the exhaust and the plug will be extremely black with soot.

(me) If you do as Cowtipper suggests you basicly have a reducer cone and I think that is probably what you want. Won't do much for the loudness though if you are after a quieter pipe.

(Cowtipper) Touche, Ian. It's actually a little different and has a bit of a different effect. With the Baffle, it points into the pipe towards the head. With the stock reducer, it points towards the exit, which is basically just a choke (or bottleneck). Using the baffle, the exhaust pulse is forced to flow through the choke and around it. Cutting the tabs off allows for a very free path since the air flowing around the baffle can also flow back through the holes in the baffle. I found it to be very efficient and it cuts down the db at idle.

Just one (from some of the recent posts from others) apparently ignorant tinker's experience. Take it for what it is.

(me)I know apparently I'm ignorant too. I didn't realise you had put them in backwards. That should offer extra back pressure as to the performance end or the sound end I can't say since I have never tried that.

I got the darn quote boxes all messed up and this was the easiest fix!

Cowtipper, you mean to cut the tabs off of the original baffles that came with the bubs? You also mentioned putting some 6" baffles down the header. If I do that, will I have to drill some new holes in the pipes to attach them? Apologize if I seem ignorant, but I'm pretty new to the whole bafflectomy thing.

I wouldn't cut on the BUB baffles. I think someone said they are $35 or so to replace them. I was talking about the $10 "beer can" baffles. There are triangle shaped tabs folded into the center of the baffle for back pressure. If you really want it to flow, bend them out past the baffle tube and cut them off. You can kinda see them in this picture:



As for mounting them, I don't like drilling holes in my pipes. If you look at the screw set in the pic, I flip that over and weld the nut to the baffle. Then I put the screw inside the baffle so the screw end tightens against the inside of the header wall.

If you want to try this and you do not have a welder handy, have the people ship them to me and I'll weld them up for you and ship them to you.

P.S. I'm happy to help you. I've been the recipient of so much from this site, I'm glad to contribute when I can.

Those are much more restricted than the ones I have seen.The ones I have had in the past you could shove a piece or rebar down the center without bending any of the tabs. Those look pretty darn closed off!

Its not as bad as it looks- the punch outs are staggered. I did the rebar trick on mine, too.

At the risk of sounding dense, these insert into the headers themselves then, or into the Bub exhausts? Also, when you mount them, tightening the screw against the inside of the header wall doesn't allow them to rattle around on the inside at all?

Yes, into the headers. Mine haven't rattled at all. Of course, I may just not be able to hear it. If you do choose to drill a hole, make sure you leave enough room to slip the pipes back on and clear the bolt head. At the very least, it is easier to put the bolt in if the nut is welded to the baffle.

I have never had them rattle but I have only used them in drag pipes. They will go in any 1 3/4 pipe. Weather that be the header pipe or any other 1 3/4 part of the exhaust. You will have to drill a hole for the bolt. If they don't fit well in the pipe then they could rattle or even cause a crack.That being said I have used them in hundreds of drag pipes with no problem.

Well, sounds worth trying. Can't beat it at nine dollars. I'd appreciate the help with the welding if you're serious about the offer. If you send me a pm with your address, I'll have it sent to you and pm you with my address as well. If you have a paypal account just send that info as well and I'd be happy to cover any expense and shipping as well. By the way, I looked on ebay and saw only a four inch baffle. Didn't see an eight inch available from your friend shotglass. Also, inserting the baffle into the header, I assume I am inserting this with the skinny end first, and the head with the screw and nut will follow last, to be screwed down at that point. You mentioned something about them being reversed so I wasn't sure. Also, I am assuming that the final product of this will be somewhat tamer than what I have now at idle, but not as tame as the stock Bubs, as I'm hoping for something kind of in between. Is all this accurate?

yep sounds correct to me. I wasn't offering to do the welding but can if you want. You could just go to a local guy though and save the shipping. I would rather have the pipe for bolt size. So you wouldn't have to drill the hole in the pipe. Let me know.

It was actually cowtipper that had offered to do the welding, but I certainly appreciate the help otherwise. Both of you guys have been very helpful with this.

OK thats cool, glad I was of some help.

This is what I'm talking about:




If you can hold off a couple days, I might have a set I can send you.