please help!! I wanna buy this bike&engine tommrrow !!

Mike, I think two down from the top is where most end up being. So there or three down is a good place to start. Easy enough to change anyway. A bit fiddly the first few times but you'll get pretty quick at it in time.

Those speed carbs can breath ok. If you take the red cover off you'll see where the spaces are for air to get in. You can also drill a few holes in that red cover if you feel it's needed, but take the cover off first or that little foam filter will twist around the drill bit and be destroyed. But that's an easy fix if it happens.

So it sounds like you want to take the cap off the muffler, get in there and remove some of the catalytic converter (crimped part)? Some of those mufflers have that whole baffle and "cat" part welded in so it might be too big a job.

There's a good thread about drilling into the muffler cap and by that they mean that bottom end in your photo.

Also about mufflers, Tom pointed out that you should check the flange to see if the weld will interfere with the nuts when you bolt it up. I checked mine and sure enough the weld was not allowing the nuts to snug up flush against the flange. That situation would allow the muffler to vibrate and move and eventually break or mangle the exhaust studs. Always heed Tom's advice and that's about the best advice that I can give you.

I don't think the wants to run the muffler with the end cap off, I think he just wants to remove the baffle.

There's some performance to be had by removing the end cap then drilling 4 5/16" holes thru the end cap, it makes a noticeable difference mainly with acceleration and torque, and you might gain a mph or 2 as well. The noise level will go up some but it'll still be quiet enough to not annoy anyone. It's just a bit louder than stock but quieter than running it without the end cap.

I did this to a customer's bike and it worked out really well since the bike had a noticeable power increase and he didn't even notice the sound difference.

dtv5403 said:

I don't think the wants to run the muffler with the end cap off, I think he just wants to remove the baffle.

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The end cap and the tube on it IS the baffle. Now, there is a honeycone baffle way up inside where the pipe welds on. So there are actually two baffles in the pipe. one you can remove and one ya cant. If I can find a pic of the shorty pipe I made I'll show ya what I mean.
fatdaddy.

I've had really good luck with customer's bikes just by drilling the extra holes in the end cap and leaving everything inside the muffler alone. What's inside these mufflers is a few plates welded to the tube to act as baffles and the pipe it's self is capped off with a both welded to the end and it has several holes drilled into the side of the pipe inside the can. This all flows well enough when using a stock or mildly ported engine, it just doesn't have the ability to exit due to a very small outlet pipe.
There's no need to cut the small pipe welded to the end cap short, just drill the extra holes and you'll get some extra torque and gain a mph or 2 while staying quiet. Any further mods to the exhaust is best done by getting a better pipe with an expansion chamber. These can be made surprisingly quiet by capping off the outlet and welding a stinger pipe into the belly section. There are a few videos out there demonstrating how quiet this type setup is and this gives the best of both worlds since you get much better performance with a stock like noise level. The only drawback to side bleed pipes is they can be bulky and can also be difficult to make look good.

Some of the kit mufflers come with removable honeycomb baffles, but you can also cut the pipes with the non removable baffles apart and still get the honeycomb out, them weld the pipe back together. I cut a pipe apart and got the honeycomb baffle out once and put it back together. I also had another bike that had a puch hi-hi head and a torquer pipe from arrow. The bike with the gutted stock pipe and stock head performed noticeably better than the bike with the puch head and torquer pipe. But I now have a pipe where the honeycomb baffle just slides right out and I've already removed it. But I'm not even going to use this pipe since I'm not building a kit bike. It was given to me along with a slew of other parts and two junked frames. I was going to try to get a running bike out of the deal, but I didn't realize how bad of a shape the two frames were in until I brought them home and they weren't salvageable without spending money I did not have, which defeated the purpose of getting a free bike, since any money I would have had would've gone into my custom project, and the whole reason I picked up the free bikes was because I didn't have money to finish my custom project. Anyway, I'm babbling. I don't know if everyone will have the same results as I did, but the gutted stock pipe performed much better for me than the torquer pipe.

Without the bad times, we probably wouldn't know what the good times really were.

site fails

seems to die about the time a third party script tries to assign a tracking ID for SEO

happens a lot at my place - kinda like when 'puters first came out and everyone was going to balance their checkbook, but within a few weeks it was sitting in closet

lot of folks buy one, ride three times and decide it ain't for them - I guess that sometimes just getting up 1/2 hour earlier to get to work on time is too much for them