Announcement

Collapse
No announcement yet.

New exhaust reverse megaphones.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    New exhaust reverse megaphones.

    I'm looking a scooping up a set of reverse megaphones on ebay, they are 18" long and that's about all the details I'm given. As the mufflers were rusted straight through on my Gsx400L I needed new ones anyways. Does anybody know if the air flow will be much different than stock? I don't particularly want to have to go back and re tune the carbs.



    #2
    Do you have pods? Do you still have the cross-over pipe between headers? If yes, I wouldn't venture an opinion.

    But with my standard airbox/headers, just about anything goes that clamps on around the outside of the pipe....only ones I've tried that tend to "pukka pukka" on deceleration are a pair of shorty Screamin Eagles I picked up as a joke. They're kind of embarrassing at 7000 rpm but they sound pretty cool at idle!
    Right now, I've got some nice Harley mufflers on . These are Heavy-built and nice chrome...and I bet you can buy them from some Harley guy for what you are paying for those...

    These ones you show. They should work unless a child-labourer lost their hand inside ...cheapo! they look like the chrome is not going to last very long at all! I bet they don't weigh very much either, which is a clue to longevity,ime, however nice it is to save money on Ebay shipping weight.

    Comment


      #3
      when i got my bike in non running condition and it had some cheap pods on it with these jets

      _______________MY BIKE_____ STOCK
      MAIN AIR JET _____ 130________ 117.5
      PILOT JET__________42.5 _______ 42.5
      PILOT AIR JET _____ 125 _______ 125

      the old mufflers have been cut off, i still have the cross pipe though.

      Comment


        #4
        I bought a set for my GSX 400 - now morphing into a GS450 - a month ago from Modern Motorcycles in Vancouver. As I recall, they were $79.95 each and very nicely made from substantial materials. I haven't fitted them yet because my stock originals are still intact, but will herniate their bulges soon and wanted to not be in a hurry buying replacements. 'Modern' Murray showed me two kinds, the loud ones and the quiet ones. The quiet ones have a baffling arrangement that is similar to stock whereas the loud model is just a straight through with a bulge around it where the baffling should have been. IOW, it's just a reverse megaphone with an exit spigot. The quiet ones look very similar to the stock original.

        Buying on Ebay, it's hard to know what's inside. If you can see through it, it's going to be loud. Given that it's a lot more costly to install an actual baffling system than some sort of 'attenuation ornament' pop riveted to the end, most of the bargain exhaust systems tend to be 'free flowing'. If that's what you're looking for, then it's a lot easier. If not, then I'd be doing some research and would rather have the pipe in hand before buying. When you take into account the $CDN and shipping and duty and such, you might be better off buying something from a local dealer who has stock in hand and experience with it.

        Fitting can be a challenge, if you want to do it right. The exhaust system hangs from the head and from the rear mounts. If you just clamp it on in the middle, the headers aren't really supported like they originally were; I've done it and nothing catastrophic happened, but welding the pipes to the header is a lot more structurally sound. If you're going to pay someone to do that, you want to have the right good quality mufflers to begin with. You'll also have to contend with the side and centerstands and rear axle and such before you weld it up. It's easy to do an install and then have a surprise when you roll it off the stand.

        Stock jetting on a GSX 400 should be a 115 main jet. I find that to be on the edge of too lean as it is, and a 117.5 would be worth trying out; probably 120 would be max unless you go down the rabbit hole and get into pods. It's not hard to change main jets if you put allen head screws on the float bowls when you had them out. You won't have to change the idle or midrange setting [needle] if you've left the intake stock. The compression is 10.5:1 on a GSX which was fine for Euro gas in the '80's but really not compatible with today, which is one of the reasons I'm putting a 9:1 450 top end on mine.

        You also have to take into account that the ethanol fuel tends to run lean; its just an inevitability. Fuel injection systems compensate but carburetors don't, and even my lawnmower lean surges on the stuff. There's a night and day difference to how these motors run between Chevron 94 ethanol free and the general pump premium. They even start differently [no choke!] so I'd recommend going up one main jet side just because of the fuel reality. Big Oil doesn't really care about carburetors anymore, unsurprisingly. Unless they've fixed it, Shell's new V Power ethanol free premium is a disaster; don't get me started…. I used to think all gasoline was the same; now some of it is so bad it even pings when you wash parts in it!

        Also consider that returning an item across the border gets complicated and costly, and then you still don't have any mufflers. I'd look into what Canada's Motorcycle has for sale before chasing Ebay bargains. At least you can send it back.
        '82 GS450T

        Comment


          #5
          holly smokes! you seem to have a TON of knowledge about this stuff, I've been to modern a few times, maybe ill head down there and check to see what theyve got for me. I'm owed a few favors from a welder friend of mine so i could go the route of getting them welded up. As for the intake, I'd like to run pods with the reverse style cones but id also like the bike to run nicely.

          And what gas are you suggesting i use? chevron 94? I've also got a 1980 CB250RS I'm still riding, maybe ill try putting a different gas in it.

          Comment


            #6
            Murray had some nice quality reverse cone style 'mufflers' leaning against the wall at the left end of the parts counter, last I was there. They're more the Dunstall type as I recall so may be a bit long on a 400L, plus there's nothing much inside. The quiet ones he had - he said he got them through Suzuki Canada - leaning beside them I bought. He may or may not have some more. Very similar looking to the stock pipe but a wee bit longer.

            I've seen some rather short reverse cone ones that would fit your bike and also are short enough [maybe?] to allow the back axle to slide out easily, but they'll wake the neighbours for sure. I can't tell you how loud you want your bike to be, or not to be, but be assured that a twin can make plenty of racket. It's just the same bang as a four with longer spaces in between.

            I ran a GS400 with a Mac 2 into 1 and pods, and a Dynojet kit. I think it gained more attitude than actual usable horsepower. On a GSX you have to accept that the intake tract is considerably smaller than on a GS400 or 450 head - 30mm vs 36mm - although the ports on the GS always seemed oversized considering the carbs are only 34mm and have a butterfly across them. The stock air box is pretty huge and non restrictive, unlike the early GS400s, so pods won't gain you as much there. One of the things I like about the 4 valve motors is that the thing is modern and linear. It idles like an industrial motor and has no flat spots or valleys all the way to 10k, just a phase change to 'serious' above about 6500. If you need to gain power it will only come at high rpm and you may lose the linearity down low. A freer flowing exhaust would maybe gain a little up top, but how much time do you actually spend at 9000 rpm wide open? The 4 valve head is capable of flowing way past 10k so I think they just put a limited and sharp cornered intake port and somewhat small valves to keep it from winding to 13k like the new bikes do.

            If you just have to ditch the air box, I'd consider using a short tube that would act like a velocity stack and put the pods aft of that. It's tempting to just clamp the pods to the carbs, but you're asking the flow to become organized in a very short distance - shorter than stock.

            As to gas, with this motor you'll have to run premium as a minimum and Chevron 94 is what it relaxes and runs happy on. You can hear it - or Not hear it in this case. I tried various tweaks to make it run on mid grade and, well, sort of - on a cool day. Regular sounds like a flamenco cafe. 92 usually fixes the pinging, but it still sounds harsh and tinny when its up on the cam. These heads are known for cracking, and I think a lot of that is helped along by low level pinging.

            I don't know much about the Honda, but it's probably going to like some more octane rating, and all of these old carbureted air coolers will be better off without ethanol. You also have to consider the corrosion problems with long term storage with ethanol.
            '82 GS450T

            Comment


              #7
              I'm definitely looking for something shorter than stock, I want to be able to remove the rear axle if need be without having to wrestle with the exhaust. I like my neighbors at the moment and don't particularly like overly loud bikes, however I do like the bike to have a nice rumble. Ill give those few places a call and see what they have to offer, ill also look into tossing a spacer between the pods and carbs. How long should I be thinking? 1" suffice?

              Comment


                #8
                Originally posted by C_OUELLET View Post
                I want to be able to remove the rear axle if need be without having to wrestle with the exhaust.
                Easy solution there is to remove one end of each shock, then either raise the wheel or lower it, the axle will slide right out.

                .
                sigpic
                mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                #2 son: 1980 GS1000G
                Family Portrait
                Siblings and Spouses
                Mom's first ride
                Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                (Click on my username in the upper-left corner for e-mail info.)

                Comment


                  #9
                  Originally posted by C_OUELLET View Post
                  I'm definitely looking for something shorter than stock, I want to be able to remove the rear axle if need be without having to wrestle with the exhaust. I like my neighbors at the moment and don't particularly like overly loud bikes, however I do like the bike to have a nice rumble. Ill give those few places a call and see what they have to offer, ill also look into tossing a spacer between the pods and carbs. How long should I be thinking? 1" suffice?
                  For some reason, I always use the minimum 1.5 times the diameter 'rule' for this. There's probably some aerodynamic formula, but there would probably be some length below which it doesn't get a chance to finish its job and thus does nothing. Given the short intake tract on these motors, I'd say a velocity stack for race tuning might be 4-6" long so maybe half that? Measure the runner from the air box and add a bit is what I'd do. You never know, those fool carbs might not know the air box is gone….

                  But then, I haven't done this and as I sometime do some gravel roads and such I'm avoiding pods. The stock air box on these bikes is so good that you hate to toss it; plus you lose a place to vent the breather hose. OTOH, if you're ditching the side covers, it's butt ugly.

                  Long pipes with no baffle will be almost as loud as short ones. But…I think they have a lower pitch. Trombone vs trumpet. I happen to prefer the look of longer pipes, but shortening everything aft of center on bikes is the rage these days. Except the swing arm.

                  As Steve says, undoing the shocks is pretty easy. But you're going to get dirty and grumpy no matter how you do it.
                  '82 GS450T

                  Comment


                    #10
                    I got the stock main jet size wrong; it's 117.5 not 115.

                    Just as well this subject came up as I'm about to order some jets and would have ended up with way too many 117.5s.

                    Also be advised that carb parts for US 450s, while for a same size of BS34 carbs, are for a rather different model and construction of carb. I haven't had one in hand, but the pictures on the Basscliff website for tearing down a 450 carb show a rather different animal entirely. The tutorial on the 850 carb shows a 32mm version of what you would have. Be sure to download the GSX400 service manual on that site, if you haven't already.
                    '82 GS450T

                    Comment


                      #11
                      Originally posted by John Park View Post
                      I haven't had one in hand, but the pictures on the Basscliff website for tearing down a 450 carb show a rather different animal entirely.
                      Do you have a Link to this article?

                      Edit:

                      Found it in the end was BikeCliff rather than Basscliff

                      Different carb to my GS450A variant though

                      Last edited by Guest; 11-29-2015, 11:12 AM.

                      Comment


                        #12
                        Originally posted by John Park View Post
                        Also be advised that carb parts for US 450s, while for a same size of BS34 carbs, are for a rather different model and construction of carb. I haven't had one in hand, but the pictures on the Basscliff website for tearing down a 450 carb show a rather different animal entirely. The tutorial on the 850 carb shows a 32mm version of what you would have. Be sure to download the GSX400 service manual on that site, if you haven't already.
                        Also note that there are two different carbs that were used on the 450s.

                        The '80-'82 bikes used a carb that was a bit different than the other bikes, the '83-and-up bikes used one that was almost identical to the ones used on the 1000 and 1100 bikes. The jets were the same and the throat size was the same, but just about everything else was different.

                        .
                        sigpic
                        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                        #2 son: 1980 GS1000G
                        Family Portrait
                        Siblings and Spouses
                        Mom's first ride
                        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                        (Click on my username in the upper-left corner for e-mail info.)

                        Comment

                        Working...
                        X