Topic: Tailpipe baffle too restrictive? 76 cb550k 4 into 2

[kippstakes]

My bike has always been gutless, especially as the revs stack up..  it just seems to flatten out when other bikes I've been on hit their sweet spot, dig in, and start pulling (I've seen vids of my bike in action and it seems to be no different). I rebuilt the head about a year ago and popped the compression up to around 135 on all four, so she has power. Spark is strong across all cyls, and the carbs are clean with, what I believe to be, a balanced jetting config. It seems to run strong, but just struggles for some reason.

Anyway to the the point. I started researching exhaust/baffle considerations, and I think my baffles might be too restrictive for the bike. The dude who sold me the bike took a pair of 'lawnmower gears' and welded them into the pipe ends, so basically there's a plate welded into the end of each pipe with an opening about 2 cm in diam. (see pic, if it loads), which seems a touch small to me.
I'm wondering if this might be causing my power issues.

Ideas?
Thanks in advance

[evanphi]

Plug chop results?

[cougar]

Remove THAT!   ...cougar...

[flybox1]

+1 to both of the above.

What does 'balanced jetting' mean?   
what jets are in there?  what air filter are you running?

[kippstakes]

The bike came with pod filters and a 2/4 pipe config (complete with the home-job 'baffles'), which I think had the jetting thrown off a bit. I upped the mains to 105 and set the needles to the richest notch and she straightened out considerably- big power gain. This is what I meant by 'balanced'. The carbs were synced three months ago, good spark on all four.

I haven't done a chop in a while, I will get her out this weekend and get back to you.

It will be a challenge getting those things out, they're welded in and steel (can't be drilled through... by me anyway). I'll figure it out. Finding replacement baffles might also be a challenge- I have no idea what kind of pipes this guy put on here.

[cougar]

The last header/head-pipe I put on my bike was from a Hondamatic 750. It came with no muffler. I took a chrome tailpipe piece that I picked up along side the road (probably off a local Monster truck, LOL). Sanded the chrome up rough then sandblasted it to make the surface uniform. Cut off the entry pipe and replaced it with one that fit around the outlet on the header/head-pipe but slid up in the tailpipe about 2". Then I took a piece of exhaust pipe that would slide over the pipe extending into the tailpipe and run to the end of the tailpipe and made 4 cuts along the top and bottom (evenly spaced) then 3 cuts along both sides (again evenly spaced). Then I took an old busted extension from behind (toward rear of pipe) each cut and bent the edge down toward the center. Then I made a cap to fit just inside the end of the (now) muffler, welded it to the new baffle, welded a couple of tapped tabs on it to hold it in place. Wrapped it with High Temp insulation (kitchen stove insulation) and wrapped a layer of steel window screen around it (to lessen blow-out). Slid the new baffle into the muffler, screwed it down and painted it with High Temp Barbeque paint.

Looks great IMO, sounds Killer (many peoples opinion) and mostly cost time since I'm a scavenger and try to keep junk laying around (to repurpose), LOLOL!

Since I didn't take pics of the baffle (when I made it), I made one in Paint and the other is the tailpipe I found after I got done with it.

      ...cougar...

P.S. I have the tools and ability for these kinds of things.

[kippstakes]

Hey nice job. I have access to welding equipment and a good pick and pull site, so I'm sure I could throw something together.
Thanks for the rundown of your project- very interesting and resourceful.

Once I get the old rigged baffles out, how important is it that I get the correct size on the new ones (in other words, how much they will restrict exhaust flow)?

[flybox1]

Is it a 2:1 on each side?   What about finding new slip-ons for each side?
....like these from CONE.  http://www.coneeng.com/pdf/motorcycle/MC-finished-Mufflers.pdf
The quiet-er core have a decent amount of backpressure and are easy to tune your carbs to...I have one.  Its nice.

[kippstakes]

Good resource, thank you! I'm going to take a stab at getting these things out next weekend and see what happens with the performance.
Thanks again