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Thread: Super Tuning A 670 Street Avenger

  1. #31


    Hmm. I blew out the idle passages four times by now. Disassembled the carb, cleaned everything and it's still doing it.

    I did some "cleanup" just now, and moved the heater hoses further from the fuel lines.
    Then I cut some hose and put it around the fuel lines, where they where close to any parts. Will see how that goes, trying the "free" options first.

    Idle too low? Hmm, how so? It idles at 750 in gear and a little over 800 in park. I would rather have 800 in gear, but then I have to open the throttle too much.

  2. #32


    I'm to the point where I think I should put that thing back on ebay, and buy the damn Quick Fuel carburetor for it.

  3. #33


    So, after taking a break from it, I'm back to trying. Today, I fired it up and let it warm up for a minute, there was the first problem, it started right away with the choke on and idled at 1500. Normally I could give it a tiny kick, and it would idle at 1000 to 1100 right away. Now it just died. Checked and the choke was all the way open...hmm. Readjusted it a little tighter and it's fine. Solved that initial issue I guess.

    Now warmed up and choke off is a whole other story. I have an 13.5 AFR in park and that jumps to 15:1 when i put it in drive. That's with the mixture screws 2 turns out. I blew everything out with carb cleaner, in the air bleed, through the mixture screw holes etc. Also, turned the idle speed screw all the way out, then turned it in til it initially made contact, and then just a tad more. Also set the mixture screws to 1 1/2 turns.

    Now, after starting it, I had to give the speed screw about 1/2 turn to have it idle at 700 in drive. Then, I gave the mixture screws 1/4 turn at a time. I'm at 3 1/8 turns out and still barely get a 13:1 AFR in park, and 14.5:1 in drive. That just can't be, the screws are super unresponsive!? I have the secondaries almost closed, maybe 1/8 turn from contact with the stop. If I open them up too far, the carb gets even leaner and the mixture screws get even more unresponsive.
    What should I do with this???? I have my timing back to where it was when the car was running & idling good.
    Last edited by Knebel; 04-25-2015 at 10:49 PM.

  4. #34


    There is something I have not really considered yet, the PCV valve. I only have 10" vacuum in drive, but 15" in park. PCV valve closed in park, nice rich AFR; drop it in drive, and the PCV valve opens and shifts the AFR too lean! I will definitely check that out!

  5. #35


    I think I got it now. It was not the PCV valve, it was not the vacuum advance hooked up to manifold. I took off the metering block again, drilled out the IFR to .031", and flushed the block out with carb cleaner. Now my idle mixture screws are nice & responsive, and I can get a 13:1 AFR with about 1 turn out. My off idle is just around 14:1 AFR. Way better than the choppy 18:1 AFR. I'm sure I can get it a little leaner at idle & cruise, but for now I'm out of gas and got it close enough for now.

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