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  • Spark Plug Analysis

    Pulled the plugs recently.

    These came with the bike--totally stock. Then I put a TBR exhaust/headers, Unipods and rejetted as follows:

    main jets: 165f/160r
    Float bowl height: 10mmf/11mmr
    Slow jets: 142
    2.5 screws out on both

    Ran that configuration for about 4000 miles. This is how they came out:

    Front and Rear
    http://i1200.photobucket.com/albums/...s/DSCN2421.jpg
    Front only
    http://i1200.photobucket.com/albums/...s/DSCN2425.jpg
    Rear only
    http://i1200.photobucket.com/albums/...s/DSCN2429.jpg

    So it looks like the front might be a bit rich, and the rear a bit lean. So I rejetted:

    150/150
    Float bowl height: 9.2mmf/9.3mmr
    Slow: 142
    2.25 screws out on front
    2 out on rear
    New iridium plugs

    It's been about 800 miles and here are the easy access plugs:

    New front
    http://i1200.photobucket.com/albums/...s/DSCN2445.jpg
    New rear
    http://i1200.photobucket.com/albums/...s/DSCN2441.jpg
    rear closeup
    http://i1200.photobucket.com/albums/...s/DSCN2442.jpg
    front closeup
    http://i1200.photobucket.com/albums/...DSCN2445-1.jpg
    front closeup
    http://i1200.photobucket.com/albums/...DSCN2446-1.jpg


    So it would seem like the rear is pretty close to good and the front is still running a bit rich.

    In regard to power, the switch from 165/160 to 150/150 was very noticeable. The bike just didn't seem to get up and go before, but the more restrictive fuel flow apparently evened out that tendency. There is undoubtedly more tuning to do and that's what I need you for.

    Any thoughts? What would you be adjusting?

    Thanks

  • #2
    with the last changes that you made..it seems to me that the front plug should not look that dark..I wonder if something changed inside the carb..float stuck a little..or maybe even an ignition issue..rear looks spot on..not blistered.
    Last edited by zymmer4; 12-06-2010, 09:03 AM.
    Emotion is a terrible thing to fight while in the heat of passion...
    Governments Don't Create Jobs..Private Business Does...

    Comment


    • #3
      Originally Posted by zymmer4 View Post
      with the last changes that you made..it seems to me that the front plug should not look that dark..I wonder if something changed inside the carb..float stuck a little..or maybe even an ignition issue..rear looks spot on..not blistered.


      It's possible something's not working right on the front carb. Probably best to adjust the screw in a .25 turn and see if that does it. It is odd though, huh? Thought the front needed quite a bit more fuel than rear. It's been cold lately--in comparison to the other 9 months in Texas, so possibly it's temperature related...

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      • #4
        screw in

        Originally Posted by Larkin View Post
        It's possible something's not working right on the front carb. Probably best to adjust the screw in a .25 turn and see if that does it. It is odd though, huh? Thought the front needed quite a bit more fuel than rear. It's been cold lately--in comparison to the other 9 months in Texas, so possibly it's temperature related...
        Dang, it still looks like too much difference to happen all of a sudden..you took the carb bowl off..changed jets..a twiddle on the low speed screw..and presto..near fouled plug.did the tip come off the adjustment screw? did the float change level by a few mm??I just don't get it yet..
        Emotion is a terrible thing to fight while in the heat of passion...
        Governments Don't Create Jobs..Private Business Does...

        Comment


        • #5
          Seems like a big jump on the Mains - why???

          Comment


          • #6
            Originally Posted by socalrc31 View Post
            Seems like a big jump on the Mains - why???
            I went from stock 142f/138r to 165/160 on the recommendations here and elsewhere when i put on Unipods and a TBR system.

            It seemed to run better in the mids, but I could smell a lot of gas (still can) and it kinda got bogged down over about 6500. I ordered 150, 155 and 157.5 but the only ones that came in were the 150's--the others are on backorder. So I put them in, adjusted float bowl heights and fuel screws.

            Now it's strong all the way through, but that front carb is still putting in too much gas. It's better than being too lean, but still...

            Comment


            • #7
              Originally Posted by zymmer4 View Post
              Dang, it still looks like too much difference to happen all of a sudden..you took the carb bowl off..changed jets..a twiddle on the low speed screw..and presto..near fouled plug.did the tip come off the adjustment screw? did the float change level by a few mm??I just don't get it yet..
              Yes, the float heights changed by about 1mm to 1.5 each. They were previously at about 10mm and 11mm. Now they are 9.2mm and 9.3mm.

              It's possible I lost an o-ring in the fuel screw for the front. The previous one actually fell out as I was driving before I rejetted. In my infinite dumbassness I thought I could avoid rejetting by unscrewing it 3.25 turns out. Well, as things go, that's TOO FAR. Replaced by spare.

              So, that might be the problem. We'll see.

              Comment


              • #8
                Always keep float settings stock at about 9mm or risk introducing too many variables into tuning.

                Why aren't you using stock plugs ??
                Last edited by squirrelman; 12-08-2010, 08:39 PM.
                "It's only getting worse."


                MY rides: '97 VFR750, '90 Red Hawk, '88 Blue/Black Hawk, '86 RWB VFR700 (3), '86 Yamaha Radian, '90 VTR250, '89 VTR250 (2), '73 CB125, '66 Yamaha YL-1

                Sold: '86 FJ1200, '92 ZX-7, '90 Radian, '73 CB750, '89 all-white Hawk, '88 blue Hawk, '86 FZ600, '86 Yam Fazer 700 , '89 VTR250, '87 VFR700F2, '86 VFR700F.

                Comment


                • #9
                  Originally Posted by squirrelman View Post
                  Always keep float settings stock at about 9mm or risk introducing too many variables into tuning.

                  Why aren't you using stock plugs ??
                  Well... uh no good reason. I wanted to eliminate spark as a variable, but probably just introduced a new one, huh?

                  Comment


                  • #10
                    Something I recently learned as I retuned a GSF600. I couldnt get Iridiums too change color/do plug chops. The large Ceramic and small electrode dont get hot enough too change the ceramics color. When I bought stock plugs I was able too get proper readings. By the way you are only testing the Idle circuit/fuel screw. you need to also do plug chops at mid and full throttle too test needles and mainjet. The first plugs pics look good the last ones are way too rich, again thats just idle.
                    Last edited by RealDeal650; 12-09-2010, 11:00 AM.

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                    • #11
                      http://i1200.photobucket.com/albums/...s/DSCN2425.jpg These are close too perfect

                      http://i1200.photobucket.com/albums/...s/DSCN2429.jpgThese are even closer.

                      Comment


                      • #12
                        Originally Posted by RealDeal650 View Post
                        Something I recently learned as I retuned a GSF600. I couldnt get Iridiums too change color/do plug chops. The large Ceramic and small electrode dont get hot enough too change the ceramics color. When I bought stock plugs I was able too get proper readings. By the way you are only testing the Idle circuit/fuel screw. you need to also do plug chops at mid and full throttle too test needles and mainjet. The first plugs pics look good the last ones are way too rich, again thats just idle.


                        So I'm gonna have to go back to stock plugs to get good readings then? Roger that. As for testing only the idle circuit/fuel screw, I rode for several hundred miles with the new setup (150/150) before pulling the plugs, so shouldn't that have been sufficient to see the full range of throttle? I'm a total newb to tuning, so I really appreciate your and everyone elses' input.

                        The original plugs (the ones you showed) were there when I bought the bike fully stock. Probably it ran right within it's proper factory settings, so it probably hard to get a good read of the recent changes made. Yea, I'm doing this all effed up...

                        BTW, great to hear you only got a bruise. I've got a bunch of stock stuff, so let me know if you need anything. Check out my inventory here:

                        Hawk Parts for sale

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                        • #13
                          Thanks for the kind words, I had aftermarket rearsets on her from the wreck, so I put my stockers back on. Thank you for the offer.
                          Proper mid plug chop- half throttle for 20 seconds, hit the kill switch while at half throttle and pull the clutch immediately. coast too a stop. pull plugs. This tells you if your needles are set correct.

                          Wide open plug chop- full throttle for 30 seconds under load, pick a hill on the highway too kill the engine ( almost redline ) 7000 should be good repeat steps above. This tells if your mains are the right size.

                          Idle plug chop- let it idle for 60 seconds and pull plugs. This tells you if you need to turn the screw.

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                          • #14
                            What is meant by mid rang and full throttle chops is...run for several miles in the mid range RPM..then..pull in the clutch and hit the ignition stop switch..coast to a stop and pull the plugs..look at them..take picts while they are still hot...then install plugs..start up and go WFO for a little bit..need not be in top gear..3rd would do..again..pull in the clutch..kill the ignition..bring the bike to a stop.pull the plugs and read them..Be careful when you pull in the clutch at speed..it is not a normal action..It may catch you out ..don't panic..don't release the clutch lever if coasting @ 60 mph..practice the chops at moderate speed until you get the routine down..much useful info pertaining to jetting will be known to you after the mid and WFO chops.
                            Emotion is a terrible thing to fight while in the heat of passion...
                            Governments Don't Create Jobs..Private Business Does...

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                            • #15
                              Ok... That's what I was missing. Thank you both. This is invaluable info and probably it's been posted somewhere. At any rate, gracias.

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