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Carb clean: results

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  • Carb clean: results

    It finally stopped raining long enough for a test start/ride of my newly carb-cleaned '89 NT650 (bone stock). Results were 100%: started instantly, idled, pulled hard at all throttle openings/loads. Small-throttle surging, deccel popping, and part-throttle bogging all completely eliminated. (Well, ALMOST: the bike still feels just barely surge-y/"lumpy" at tiny throttle openings/ low revs, such as long, mild downhills; any thoughts?)

    Advice to past self: the new boots/insulators were a godsend; I can see where it could be a struggle else. DO replace the air-screw and valve rubber seals; I used the TYGA kit from Thailand (DHL cost 3x the parts...), which worked fine. If I had it to do again, I would spring for new jets, and float-needle and seat -- another $30 isn't going to kill me. Mine were all fine, though both slow jets screw slots were bunged up by some P.O., and the float needles both have barely visible wear but seat fine; I managed.

    Bike idles a tad low, tho I didn't touch the idle-set AFAIK, and a touch lumpy, which is not surprising given airscrew removal and reset by counting turns. Next up will be a synch.

    Thanks for listening, and earlier advice.

    --Danny (NH)

  • #2
    to eliminate slow-speed surging and off-throttle backfiring, try opening up the idle mix screw 1/4 to 1/2 turn. adjust idle speed to about 1200.
    Last edited by squirrelman; 08-12-2023, 07:43 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.


    • #3
      Followup: I took Squirrelman's advice and opened the slow-mix screws by almost a half-turn, and this indeed transformed all small-throttle performance: smoother, less (no) popping on deccel, etc. Thanks! Also balanced via Harmonizer (I feel a little guilty having one, as I use it so seldom, but there it is -- I was in the right place/time). Only needed a touchup, but now spot on and running best ever. Thx for all the advice.


      • #4
        I have a Twinmax balancer in my toolbox and honestly have never used it. I got it with a Vstrom I bought and it ran fine enough to where I never used it. I've always kind of balanced mine by ear. Before too long I am going to hook it up on my hawk and see how good or bad my ear balance game is, lol.
        88 Blue Hawk GT - Under construction but rideable (guest approved)
        89 BlackHawk 2.0 - On the lift and being assembled
        90 Hawk GT (color as to yet be determined) - Still on the shelf in crates