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Straight pipes with baffles (and I killed Santa).

  • Thread starter Thread starter Mr. Sinister
  • Start date Start date
M

Mr. Sinister

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So a buddy of mine gave me a set of louvered slip-in baffles to try on my bike. I was planning on doing a set of Emgo shorties, but I think pipes chopped at the pegs with baffles to keep the noise down will LOOK better for the style of bike I'm going for.
My question is, since these are louvered and not perforated baffles, will they give me enough back pressure to avoid a re-jet? Keep in mind the louvers directly block the flow of exhaust, and they're wrapped along the length, sealing off the louvers in the side of the pipe.
I Imagine this won't be much louder than stock, which is what I'm going for.




Here's what they look like, minus the wrap:
Baffles4x1.75g64-47.jpg


Baffles4x1.75ends64-47.JPG
 
They may be in the direct line of flow, by they do not actually form a constriction as the stock mufflers do. Hence, you will be reducing the back pressure. Wrapping them may reduce the flow area by as much as half, so you will likely be ok. Worst case you have to give the idel screw a quarter turn open, and may be increase the size of your main jets by one size.. not a huge deal. I say go for it, you should be just fine.
 
That's what I was thinking. Since they're wrapped, it's basically the same as choking the pipe size down.
 
Baffles like that actually do create a lot of backpressure, and due to the small diameter, I could see it being on the same level as what the stockers produce. Just based on pipe flows and stuff from class, that might actually be more restrictive than the stock exhaust. The bent part of the louver induces a turbulent wake and reduces flow velocity due to drag, which increases pressure. As with anything else, it's going to be a bit of trial and error.
 
I would assume a little trial and error. If the flow feels reduced, I can unwrap or partially unwrap them. Almost like a tunable pipe.
 
sounds like you are going to drive yourself crazy. my 400 used to run even with the pipes off completely, so you should be ok to get it running, it just might take some fiddling to get the power set just right.

It is correct that the shape produces a lot of turbulance, but only when the flow rate of the exhaust gas is highish, and then it is sort of a fun, non-linear relationship, so the back pressure will change with revs.
 
I like to cover all the bases before a mod. :D
The sawzall comes out this evening........
 
Aaaannnnddd 3 of the 4 exhaust bolts broke off in the head. Good times!!
Can't say I wasn't expecting it, but dammit. Going to try a Bolt-Out before drilling. Hosed them down with penetrating oil for now.
But, I did get the mufflers cut off!!
 
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Baffles don't fit, so I'm just going to fab my own!! I cut at the mid-pipe right before the welded nuts where the covers mount, which is a tiny 1 1/4" inside diameter pipe.
 
I'm gonna turf his lawn and keep him up all night with my evil modified exhaust!!
 
Oh yeah, I guess that would have been a good heads up that the stock exhaust pipes are stupidly thick. I think some are even double walled.

Simple fix if you've got a welder handy and an assortment of short pipe sections.
 
I cut the pipes with a tubing cutter, after figuring I wouldn't be able to sawzall them with the exhaust on the bike without nicking the frame up. Wish I had now, with the 3 broken exhaust bolts.
Nobody makes baffles that small, so I'll make my own. Some 7/8" pipe and Chore Boy should do the job!!
 
So, broke a hardened extractor off in the first bolt I tried removing. It just sheared off from the twisting force. Rapped my knuckles pretty good too.
It's safe to say these bolts aren't coming out. I also assume there's no drilling the extractor out, either.
So, new head, or is there something I'm not considering?
 
Those are basically harley baffles for drag pipes.
(as advertised all over ebay)

I really have no point, I'm just saying, lol.
 
I also assume there's no drilling the extractor out,
Click to expand...

Go buy a very small cold chisel like 4mm across, and get volient on the extractor with it and a hammer, you might be able to smash it it up into little bits.

if the broken up part is beneth the surface drill down to it, with a squared off bit.
 
So I thought quite a bit about this. I can probably use a left hand drill bit on the 2 broken bolts, and I was thinking an 8mm diamond hole saw on the one with the extractor in it. Since the bolt is 8mm, it should cut right around the outside where the extractor isn't. Then some work with taps and dies to clean the hole back up.
 
I guess my first question is why was teh exhaust held on with bolts? they are supposed to be on threaded studs and secured with a nut.

Extractors are evil most of the time, and I second the recommendation to smash it in to bits. As for the diamond hole saw, be careful. Think you can line that one up perfectly? The aluminum head will be a lot softer than the steel bolt AND if you get any aluminum on the diamond cutting surface, it will stick to the surface of the hole saw, loading it, and it will not cut anymore. Take it from the expert on this one.. it is likely to ruin your saw, and make a mess of the head.

smash out the extractor (being careful not to mash the threads), and then use a small drill, say 3mm, then heat it up and hammer a 1/8 rod down the hole. let it all cool and use the rod to pull out the bolt.
 
BentRod said:
I guess my first question is why was teh exhaust held on with bolts? they are supposed to be on threaded studs and secured with a nut.

Extractors are evil most of the time, and I second the recommendation to smash it in to bits. As for the diamond hole saw, be careful. Think you can line that one up perfectly? The aluminum head will be a lot softer than the steel bolt AND if you get any aluminum on the diamond cutting surface, it will stick to the surface of the hole saw, loading it, and it will not cut anymore. Take it from the expert on this one.. it is likely to ruin your saw, and make a mess of the head.

smash out the extractor (being careful not to mash the threads), and then use a small drill, say 3mm, then heat it up and hammer a 1/8 rod down the hole. let it all cool and use the rod to pull out the bolt.
Click to expand...

Good question, and I was wondering the same.

Extractors certainly have not won my praise.
Given the spot where I have to work, I don't see many other options beyond the hole saw. I figured to go slow, and pull it out every few mm to clean the tip. A very narrow chisel might get in there, but the extractor is broken off below the surface of the head. If I mess the hole up or get it off center, so be it. There appears to be enough material to handle it, and it's not like it's critical that the bolt goes in perfectly. I just need it to apply some clamping force to the exhaust flange. I'm even considering welding a stud to what's left in the bolt hole. I mean if I exerted enough force to shear (twisting force, not lateral force) a hardened extractor, I don't think that bolt is coming out. Even if it did, it's probably bringing the aluminum threads out with it. Had the extractor not broken off, I could left hand drill it. But if a frog had wings......

I guess I just can't see smashing the extractor. There is little room to work here. If the motor were on a stand, maybe. This is the lower bolt on the right side port. You need a sturdy punch and a heavy hammer due to the hardness of the materials, but you're working around delicate aluminum. One slip and you could be in a lot of trouble.
I would think heating the bolt enough to do anything is going to damage the aluminum head.
 
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