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    #1

    Still have power problems

    Still can't get the wife's 81 450 to go faster than 55-60 mph. She has been riding it for a while. Past work-Carbs. rebuilt with new o-rings,new carb. boot o-rings, new air filter, new plugs, new sparkplug caps, new coils,coil relay mod., new r/r, all new elec. connectors, valves adjusted, new spade fusebox, new wheel bearings, new chain, new tires, new exhust head gaskets, brakes all rebuilt,new petcock. Just checked compression and got 150 on both cylinders. Took carbs back off and cleaned all jets, openings, and checked float heights.(did change one a bit-both at about 22.7mm). Carbs screws were at 2 1/2, but after working on it today moved them down to 1 3/4-seemed to idle better there. Didn't resync. today, but had done not long ago. Plugs were a bit black with small amount of soot. Took exhust off and made sure nothing blocked, or loose inside(found nothing). Bike now seems to take off quicker, but still can't get it up to past 55 or 60 even in 5th gear, and worse if in 6th. Any ideas greatly appreciated! terrylee
    Last edited by Guest; 06-28-2011, 08:50 AM.
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    #2
    Originally posted by terrylee View Post
    Still can't get the wife's 81 450 to go faster than 55-60 mph. She has been riding it for a while. Past work-Carbs. rebuilt with new o-rings,new carb. boot o-rings, new air filter, new plugs, new sparkplug caps, new coils,coil relay mod., new r/r, all new elec. connectors, valves adjusted, new spade fusebox, new wheel bearings, new chain, new tires, new exhust head gaskets, brakes all rebuilt. Just checked compression and got 150 on both cylinders. Took carbs back off and cleaned all jets, openings, and checked float heights.(did change one a bit-both at about 22.7mm). Carbs screws were at 2 1/2, but after working on it today moved them down to 1 3/4-seemed to idle better there. Didn't resync. today, but had done not long ago. Plugs were a bit black with small amount of soot. Took exhust off and made sure nothing blocked, or loose inside(found nothing). Bike now seems to take off quicker, but still can't get it up to past 55 or 60 even in 5th gear, and worse if in 6th. Any ideas greatly appreciated! terrylee
    Does it rev up ok as you go thru gears and then just fall flat as you hit 55mph ? Did you check to make sure petcock is delivering copious amounts of fuel to carbs? Is tank vent not blocked?
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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      #3
      Does rev fine through all gears till you try to get up to 50-60 in 5th gear and just seems to want to go faster, but won't. Sorry, forgot to mention, petcock is also new. I will try the gas cap, haven't cleaned that yet. terrylee

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        #4
        This might sound ridiculous, but is it possible that some how the PO rigged up a limiter or something? I find it a little weird that it will run through rev range fine and just cut in that speed range. I'd snoop around for some extra wires coming off the speedo and front wheel. I realize it sounds kind of stupid, but what have you got to lose at this point.

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          #5
          Hey I'll check anything at this point. thanks terrylee

          Comment

            #6
            Originally posted by terrylee View Post
            Hey I'll check anything at this point. thanks terrylee
            Open up the ignition cover on the right side and check to see if the mechanical advance is working for the ignition should be able to grab it with your fingers and turn it, it should spring back. if it is stuck free it up.Just happened on my 1000
            1984 GS1100GK newest addition to the heard
            80 GS 1000gt- most favorite ride love this bike
            1978 GS1000E- Known as "RoadKill" , Finished :D
            83 gs750ed- first new purchase
            85 EX500- vintage track weapon
            1958Ducati 98 Tourismo
            “Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
            If it isn't going to make it faster or safer it isn't worth doing

            Comment

              #7
              Originally posted by terrylee View Post
              Hey I'll check anything at this point. thanks terrylee
              A rev limiter would work in all gears, and you said it reved ok till you got to fifth and 55 mph- it's starved for fuel/air mixture. Will it go downhill at 70 mph in 5th or 6 th?
              1981 gs650L

              "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

              Comment

                #8
                It will get up to 60-65 sometimes on flat area or down a hill, but still takes all it can do to get it to do that. I will check advance mec. terrylee

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                  #9
                  Ok, went out and tried to get mech. advance to move and spring back (it is part with small bolt through center of signal generator?) Took off sig. gen. and removed advance (has two small springs on it with small parts attached to springs),tried to get any part of it to move and wouldn't budge. Sprayed PB blaster around springs and attached part (which did seemed to have rust on them). Is there a trick to freeing this part up? terrylee

                  Comment

                    #10
                    Originally posted by terrylee View Post
                    Ok, went out and tried to get mech. advance to move and spring back (it is part with small bolt through center of signal generator?) Took off sig. gen. and removed advance (has two small springs on it with small parts attached to springs),tried to get any part of it to move and wouldn't budge. Sprayed PB blaster around springs and attached part (which did seemed to have rust on them). Is there a trick to freeing this part up? terrylee
                    Holding the backing plate in one hand and twisting the projection (the tab that swings by signal coils), it should move slightly clockwise as springs stretch. If this is frozen, I don't see how motor reved passed 3000 rpm without lots of complaints.
                    1981 gs650L

                    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

                    Comment

                      #11
                      Will recheck again tonight, couldn't seem to get it to move, but bike will rev, to 5-6000 when riding. terrylee

                      Comment

                        #12
                        One thing I don't see mentioned are the clutch springs. Could your clutch be slipping? Bike will rev in high gear but bike won't accelerate real well. They are cheap and if original probably should be replaced. You can remove them and measure them, there is a spec in the service manual.

                        Comment

                          #13
                          Okay, just to clarify, the bike will only rev to 6,000 in every gear?

                          Or just 5th?

                          You should be able to go faster than 60 in 3rd or 4th
                          1978 GS 1000 (since new)
                          1979 GS 1000 (The Fridge, superbike replica project)
                          1978 GS 1000 (parts)
                          1981 GS 850 (anyone want a project?)
                          1981 GPZ 550 (backroad screamer)
                          1970 450 Mk IIID (THUMP!)
                          2007 DRz 400S
                          1999 ATK 490ES
                          1994 DR 350SES

                          Comment

                            #14
                            One other thing I was thinking was gearing... are the stock sprockets on there? According to the parts fiche 16T front, 43T rear...

                            And just to be sure we're all on the same page with the timing advance mechanism, this is it:



                            And yes it should move rather easily with a little pressure...
                            1982 GS450E - The Wee Beastie
                            1984 GSX750S Katana 7/11 - Kit Kat - BOTM May 2020

                            sigpic

                            450 Refresh thread: https://www.thegsresources.com/_foru...-GS450-Refresh

                            Katana 7/11 thread: http://www.thegsresources.com/_forum...84-Katana-7-11

                            Comment

                              #15
                              Sorry has new clucth springs and cleaned and measured (all in spec) plates. To be honest I don't think I have tried to get it up to 60 in 3rd or 4th gear, maybe I was afraid it would hurst something. Don't think I have had it past 6000, since I'm only trying for speed. You can get it to 55-60 and on rare times up to 65 in 5th gear, but seems to lose power when you shift to 6th gear. Also will lose speed going up a hill, and it rare it will hold speed if you give it more throttle. I feels like it wants to go faster but just not enough power to do it. terrylee

                              Comment

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