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Bike has 0 power under load when under 4000rpm?

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    #16
    Okay so I did a compression test and here's what I found. 1 - 110 2- 105 3- 101 4- 118. I'm not sure if that's low enough to warrant the issues i'm having, someone advise please.

    Here's the craziest thing I found; the spark plug on cylinder 3 was literally a different spark plug, it was DR8EA as opposed to D8EA. That's what I get for trusting autozone I guess, I was very, very surprised that I didn't notice when gapping and installing. The cylinder was still firing before, but it's definitely a bit better/smoother now.

    Chuck; I remember you saying that 2 of my needlejets were different and you drilled them out to the proper size. Something I've noticed is that once moving at low rpm's in first gear(lets say 2000rpm, where youre barely moving), the bike will accept gas so long as it's just where the throttle is first engaged, so you're able to stay coasting and moving (slowly) without a problem. The issue is that it bogs when engaging the throttle anymore than that if it's under like 3500rpm. Do you think this could be the because of the needle jets?

    As for the oil, I did change it while I was working on the bike, so maybe that could be the problem? I put in the amsoil dominator motorcycle oil. But I'm not sure if it's a clutch problem because if the clutch was slipping, wouldn't it still rev up and just not accelerate?
    1982 GS650GL

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      #17
      And as a reminder because there seems to be some confusion, bench and vacuum sync were just done, the bike starts fairly easily and idles perfectly, has no problem accepting gas in neutral or with the clutch in, and rides great above 3000rpm. Everything is completely stock, and I feel that there are no airleaks, I have new intake boots o-rings and airfilter and everything is set well and very much tightened down
      Last edited by Cmarino; 08-25-2021, 01:10 PM.
      1982 GS650GL

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        #18
        Originally posted by Cmarino View Post

        Here's the craziest thing I found; the spark plug on cylinder 3 was literally a different spark plug, it was DR8EA as opposed to D8EA. That's what I get for trusting autozone I guess, I was very, very surprised that I didn't notice when gapping and installing. The cylinder was still firing before, but it's definitely a bit better/smoother now.?
        Howdy neighbor ;-)

        How do all the spark plugs look color wise?

        Has the tank and intake fuel filter ever been cleaned.

        Are you running an in-line fuel filter?
        Jim, in Central New York State.

        1980 GS750E (bought used June,1983)
        1968 CB350 Super Sport (bought new Oct,1968)
        1962 CA77 305 Dream (bought used Feb,1963)

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          #19
          Originally posted by Cmarino View Post
          And as a reminder because there seems to be some confusion, bench and vacuum sync were just done,
          Which carb sync tool do you use?
          And at what rpm did you do the sync?
          Jim, in Central New York State.

          1980 GS750E (bought used June,1983)
          1968 CB350 Super Sport (bought new Oct,1968)
          1962 CA77 305 Dream (bought used Feb,1963)

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            #20
            Originally posted by pdqford View Post
            Howdy neighbor ;-)

            How do all the spark plugs look color wise?

            Has the tank and intake fuel filter ever been cleaned.

            Are you running an in-line fuel filter?
            I can insert a picture of the plugs later today and I'll take a video of how the bike runs tomorrow to make it more clear for everyone, but for now the plugs are black on the metal and a slight dusting of black on the ceramic; no tan anywhere, just black/white. Mixture screws are 2.5 out

            Carb sync was done at a local shop so I'm not sure of the specifics, I didn't want to buy the tool so I had them do it.

            Brand new petcock with no fuel filter, my old petcock seems pretty clean so I'm not worried about the tank, replaced because it was backfeeding into the vacuum line
            1982 GS650GL

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              #21
              BR is the NGK race version of the B8 plug. And according to the parts fiche 2 of the MAIN JETS were wrong so according to the chart below i did use number drills and made them all the same. you got my number..call me.

              MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
              1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

              NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


              I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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                #22
                According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

                By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons
                Last edited by chuck hahn; 08-25-2021, 07:06 PM.
                MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                Comment


                  #23
                  Originally posted by chuck hahn View Post
                  BR is the NGK race version of the B8 plug.
                  The R there in an NGK denotes that it's a resistor plug, but NGK do a range of racing plugs. Istr an odd R in some plug types that did denote Racing use, but what make it was, I don't recall.
                  ---- Dave
                  79 GS850N - Might be a trike soon.
                  80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
                  79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
                  92 XJ900F - Fairly Stock, for now.

                  Only a dog knows why a motorcyclist sticks his head out of a car window

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                    #24
                    An email from NGK directly stated its their race series that replaces B8ES,that how i remembered it. i think the thread was about NGK rumor about going out of production. May revisit tat thread to read the response to the inquiry i sent them

                    EDIT.. I STAND CORRECTED. It does denote a resistor plug.............


                    Last edited by chuck hahn; 08-25-2021, 08:20 PM.
                    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                    Comment


                      #25
                      Originally posted by chuck hahn View Post
                      According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

                      By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons
                      have the valves been set to spec. Cant seem to see that anywhere
                      1983 GS 550 LD
                      2009 BMW K1300s

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                        #26
                        I have a 82 gs750 with the exact same problem it used to be a perfect running bike until the previous owner cleaned the carbs. Broke the pilot jet off in no4 and had to put a new carb on. I found 2.5 turns out on the mixture is good. starts perfect throttle doesn't hang no back fire. From what i have read on your post it has to be a carb issue as it is the only thing that made this bike run bad. Will be interested how you get on.
                        1982 gs750gl shaft drive
                        1980xs650
                        1980cb750ka
                        1990gsxr1100l

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                          #27
                          Originally posted by Grimly View Post
                          The R there in an NGK denotes that it's a resistor plug, but NGK do a range of racing plugs. Istr an odd R in some plug types that did denote Racing use, but what make it was, I don't recall.
                          https://www.ngk.com.au/technical_inf...g-spark-plugs/
                          You are correct.
                          The code for an NGK racing plug starts with an R but confusingly they also have a range of race plugs that end EG.
                          The R in BR denotes a resistor plug.
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                            #28
                            Originally posted by Cmarino View Post
                            Okay so I did a compression test and here's what I found. 1 - 110 2- 105 3- 101 4- 118.
                            Originally posted by chuck hahn View Post
                            According to the service manual (page 3-9) standard compression on a WARMED UP engine is 142 to 199. With a LOWEST LIMIT of 100. IF you arent doing the compression check with the throttle wide open redo the test. IF you did have it wide open then your compression numbers as posted indicate its time to rebuild that top end. Also the parts fiche says the main jets are #110.

                            By rebuild i mean measure bore wear per service manual too...not just throw new rings on the pistons
                            Why is that, Chuck ?
                            Ofcourse i agree #3 @ 101 is not high, but still within service limits.

                            But if performed on a cold engine that would mean compression is higher.
                            And if performed with throttle closed, also means compression is higher.
                            Rijk

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                            "The thing about freedom - it's never free"

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