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Honda Unicorn

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  • #3031
    Re: Honda Unicorn

    Originally posted by RohIIT View Post
    i am using a donor 2009 unicorn run 25k . Only periodic services has been done and nothing else. Everything from chain to tyre is stock.

    Problem 1 : Bike doesnt seem to go above 80 , need to rev real hard 6-7k each gear to get it there. Is it common for you guys too ? My xtreme (16k done) pulls to 90 in no time .

    Problem 2 : Acceleration is slow , my 5th gear 4k rpm speed is 50-52kmph. So clutch seems ok to me . Chain is also correctly tensioned. Tappets also set correctly.

    Problem 3 : kick starting doesnt need much effort , which makes me think does this bike suffer from compression issue ? i checked spark plug it was dry , so it comes down to valves . Does unicorn suffer from valve leakage ?

    Please shed some light over my queries. Thank You
    Shame that you didn't get an answer for 3 weeks. Although I am by no means an expert, I'm gonna give it a ry.

    1. Yes, acceleration beyond 80 kph is terrible. Although I have done 100 kph, you need lots of time and a straight road for it.

    2. Yes, when in the 5th gear at 4K RPM the speed is exactly 50kph. Normal.

    3. I use the electric start 90% of the time. Are you experiencing other symptoms of a compression leak? Like loss of power? Also see if the head of the cylinder is leaking liquid. There will spots of dried liquid in that case. I have never experienced valve leakage so far(ridden 14760 kms, and quite fast riding as well.)

    Comment

    • #3032
      Re: Honda Unicorn

      Originally posted by RohIIT View Post
      Problem 2 : Acceleration is slow , my 5th gear 4k rpm speed is 50-52kmph. So clutch seems ok to me . Chain is also correctly tensioned. Tappets also set correctly.
      AFAIK, Unicorn is tall geared compared to Hunk/Xtreme. Remember the 15T sprocket discussions we had in Xtreme thread?
      So I believe it should do more than 50 kmph at 4k in 5th gear.
      Last edited by SatSon; 01-08-2016, 11:24 AM.

      Comment

      • #3033
        Re: Honda Unicorn

        Originally posted by SatSon View Post
        AFAIK, Unicorn is tall geared compared to Hunk/Xtreme. Remember the 15T sprocket discussions we had in Xtreme thread?
        So I believe it should do more than 50 kmph at 4k in 5th gear.
        I believe unicorn runs 15/42 combination that gives us drive ratio of 2.8
        and xtreme runs 14/43 which translates to 3.07 .
        So yes unicorn's gearing seems to be in taller side , but as one more member said his bike does same speeds in 5th gear 4k rpm.

        So either my clutch is gone or compression is getting lower.
        Carb Tuning made easy (Thanks Sibun !)

        Comment

        • #3034
          Re: Honda Unicorn

          Guys, for the past one month or so, I've been having an issue where my engine shuts off at low RPMs. If I'm at a stop and I try to start off, the engine shuts off unless I rev it to 5-6K RPM. This didn't happen before. I have always driven by starting off at 3K RPM.

          Also, the engine randomly stalls while coming to a halt at a traffic light or something.

          I've tried tuning the carb and setting it to a richer mixture. It has slightly improved the issue, but not too much.

          Has my carb gotten blocked by the impurities in fuel? What do i do?

          Comment

          • #3035
            Re: Honda Unicorn Dazzler

            Originally posted by RohIIT View Post
            Its Secondary air injection . Same section has that textile covered pipe that goes to engine head. Its function is to reduce emission and boost mid end performance.
            What's that little black box on the carburettor with 3 wires going into it, 2 yellow and one blue?

            Comment

            • #3036
              Re: Honda Unicorn Dazzler

              Originally posted by metallica84 View Post
              What's that little black box on the carburettor with 3 wires going into it, 2 yellow and one blue?
              Throttle Position Sensor
              Carb Tuning made easy (Thanks Sibun !)

              Comment

              • #3037
                Re: Honda Unicorn Dazzler

                Originally posted by RohIIT View Post
                Yes this one , Remove the rubber pipe and block the metal lower pipe which is fixed to intake manifold and try again .
                Okay, so I tuned the carb of my unicorn using the instructions given in your signature post. I removed the air injection pipe, closed the inlet with my finger and tuned exactly like you said but my RPM never dropped no matter how much i opened the AFR screw. The rate of increase of RPM decreased, but even after rotating it to 6-7 turns out, the drop in RPM is not happening.

                What do i do now?

                Are you sure the CBZ xtreme method of tuning can be used on the Unicorn?

                Comment

                • #3038
                  Re: Honda Unicorn Dazzler

                  Originally posted by metallica84 View Post
                  Okay, so I tuned the carb of my unicorn using the instructions given in your signature post. I removed the air injection pipe, closed the inlet with my finger and tuned exactly like you said but my RPM never dropped no matter how much i opened the AFR screw. The rate of increase of RPM decreased, but even after rotating it to 6-7 turns out, the drop in RPM is not happening.

                  What do i do now?

                  Are you sure the CBZ xtreme method of tuning can be used on the Unicorn?
                  Yes i am sure, i tuned my unicorn also same way, You need to do this process slowly , i wrote it in my log that i failed 2-3 times before succeeding, also you cant try keeping afr screw 2 turns out and see the performance.

                  Edit : I saw something in your previous post that , bike is coming to halt whenever you stop ?

                  This is actually a symptom of a vacuum leak . So AFR tuning wont help at all.

                  Do this , ON AN EMPTY ROAD !

                  Test 1

                  Take bike to 40kmph and brake hard ( Pull in clutch but DONT LOCK WHEELS )
                  If bike shuts off then it is vacuum leak .

                  Test 2

                  On hot bike , twist throttle to minimal , like 1/16 of WOT ( just give it a quick turn )
                  If RPM dips and shuts off , its vacuum leak

                  Try these tests and revert
                  Last edited by RohIIT; 01-11-2016, 03:44 PM.
                  Carb Tuning made easy (Thanks Sibun !)

                  Comment

                  • #3039
                    Re: Honda Unicorn

                    Posts moved to the right thread!

                    Pls. continue discussing,
                    Got a $5 head? Get a $5 helmet.
                    Because everyone who passes, isn't a martyr!

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                    ZMR parts - https://drive.google.com/file/d/0B-U...it?usp=sharing
                    P200NS Spares' prices - https://docs.google.com/spreadsheet/...taGd5R2c#gid=0

                    Comment

                    • #3040
                      Re: Honda Unicorn Dazzler

                      Originally posted by RohIIT View Post
                      Yes i am sure, i tuned my unicorn also same way, You need to do this process slowly , i wrote it in my log that i failed 2-3 times before succeeding, also you cant try keeping afr screw 2 turns out and see the performance.

                      Edit : I saw something in your previous post that , bike is coming to halt whenever you stop ?

                      This is actually a symptom of a vacuum leak . So AFR tuning wont help at all.

                      Do this , ON AN EMPTY ROAD !

                      Test 1

                      Take bike to 40kmph and brake hard ( Pull in clutch but DONT LOCK WHEELS )
                      If bike shuts off then it is vacuum leak .

                      Test 2

                      On hot bike , twist throttle to minimal , like 1/16 of WOT ( just give it a quick turn )
                      If RPM dips and shuts off , its vacuum leak

                      Try these tests and revert
                      Vaccum leak from where?

                      Actually the symptoms of the bike are not constant at all. The engine stalls when i brake, but very randomly and very rarely. Sometimes it shows no problems even after braking.

                      Another thing is that when the engine shuts off on braking in traffic, it doesn't start even if I give it 100% throttle. I start it with the throttle closed, it starts off with RPM very low(as if the engine were cold) and then when i try to accelerate, it shuts off. Basically the same behaviour that happens when the engine is cold; but happens randomly and even though its hot.

                      I will do those tests and update this thread tomorrow. Should I do the first test on a cold or hot engine?

                      Comment

                      • #3041
                        Re: Honda Unicorn Dazzler

                        Originally posted by metallica84 View Post
                        Vaccum leak from where?

                        Actually the symptoms of the bike are not constant at all. The engine stalls when i brake, but very randomly and very rarely. Sometimes it shows no problems even after braking.

                        Another thing is that when the engine shuts off on braking in traffic, it doesn't start even if I give it 100% throttle. I start it with the throttle closed, it starts off with RPM very low(as if the engine were cold) and then when i try to accelerate, it shuts off. Basically the same behaviour that happens when the engine is cold; but happens randomly and even though its hot.

                        I will do those tests and update this thread tomorrow. Should I do the first test on a cold or hot engine?
                        Ok do these tests on hot engine , i remember i had similar issues like this and it was due to tight tappets . So after doing test if it gives negative results then we need to look in tappets.
                        Carb Tuning made easy (Thanks Sibun !)

                        Comment

                        • #3042
                          Re: Honda Unicorn Dazzler

                          Originally posted by RohIIT View Post
                          Ok do these tests on hot engine , i remember i had similar issues like this and it was due to tight tappets . So after doing test if it gives negative results then we need to look in tappets.
                          Okay, i did the tests yesterday evening and today morning and it gave negative results. However, i think i have figured out what the problem is. While tuning the carb i was being really conservative the the fuel input into the engine as i didn't want to compromise of my fuel efficiency.

                          However, after the problem was not solved after repeated tuning, I decided to forget about FE and just tune. I got a stable rev rate at about 2+1/16 turns out. I rode for around 8-9 kilometers today morning on a cold engine and my problem has lessened A LOT. I start the engine on choke and run it for around 2 minutes. after that I started to ride. Initially there were a few slight hiccups, but within 500 meters or so everything evened out.

                          What's more, the engine didn't stall in traffic, as it was doing previously.

                          The thing is, during the summers, I was running a really lean mixture(3/4 of a turn from closed position) and I was getting more than 45+ kmpl.

                          I guess I'm gonna have to forget about economy till the summers start...

                          Comment

                          • #3043
                            Re: Honda Unicorn Dazzler

                            Originally posted by metallica84 View Post
                            Okay, i did the tests yesterday evening and today morning and it gave negative results. However, i think i have figured out what the problem is. While tuning the carb i was being really conservative the the fuel input into the engine as i didn't want to compromise of my fuel efficiency.

                            However, after the problem was not solved after repeated tuning, I decided to forget about FE and just tune. I got a stable rev rate at about 2+1/16 turns out. I rode for around 8-9 kilometers today morning on a cold engine and my problem has lessened A LOT. I start the engine on choke and run it for around 2 minutes. after that I started to ride. Initially there were a few slight hiccups, but within 500 meters or so everything evened out.

                            What's more, the engine didn't stall in traffic, as it was doing previously.

                            The thing is, during the summers, I was running a really lean mixture(3/4 of a turn from closed position) and I was getting more than 45+ kmpl.

                            I guess I'm gonna have to forget about economy till the summers start...
                            Glad to know problem has resolved to quite an extent. Also FE wont increase if you run lean mixtures .



                            As you can see at at two point you get either max power or max fuel economy , but keep in mind that this is a theoretical graph and actual thing is different.

                            So point here is when we tune and get max rpm or perfect tune, it will give us max efficiency as well .
                            Carb Tuning made easy (Thanks Sibun !)

                            Comment

                            • #3044
                              Re: Honda Unicorn

                              Thanks, that's really helpful.

                              Comment

                              • #3045
                                Re: Honda Unicorn

                                Hello owners i am facing LEAKING OIL from engine head
                                I think this happened after tappet adjustment i got done few months back
                                What is advised to do ? I have not faced any issue yet and i wish to not touch engine as its running fine

                                Comment

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