PB 650 Carb. question

Discussion in 'Mechanic and Repair' started by bushwoods1, Jul 5, 2005.

  1. bushwoods1

    bushwoods1 LawnSite Member
    Posts: 101

    I have a PB 650 blower, and just recently, it has sounded like it just is'nt quite getting to full power at full throttle. I know on my other blowers, there are needle valve adjustments to "tweak" it for optimum performance. This unit does not have the needle adjustments on the carb. I'm going to check the pick up filter in the gas tank, but did not know if anyone else has run across this. Any suggestions? And while I'm asking. Why does'nt the PB 650 have the adjustment needles on the carb?
     
  2. Redneckn

    Redneckn LawnSite Senior Member
    Posts: 294

    It's an emissions thing. We have our friends in California to thank for this..
    *tree hugging hippies, hope you're happy now*
     
  3. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,140

    I work on the our PB650s and one recently was bogging down and it turned out to be some buildup in the exhaust port. It is running pretty good now but I noticed that I am leaking from both of the gasket on the cylinders, need to replace in winter if I make it. You can get a replacement carb now that has the adjustment on it. The newer units meet standard with an adjustable carb, thank heavens.
     
  4. ArchZangel

    ArchZangel LawnSite Member
    from Florida
    Posts: 24

    I have also seen that when u have a really plugged exhaust port, u get "reversion" from the carb. (u should inspect and clean ur exhaust port every season). Since the port is partially blocked, the air/flow slows down and u can get fuel spray on ur air filter. The fuel will evaporate and leave 2 storke oil on your carb. Running lean will cause bogging too. So many variantions/combonations could be the problem. Start easy stuff first. Check ur spark plug condition. Any new carb might have the low speed idle adj, but won't have the high speed, though. Also a leak down check will verify any cyl/crank case leaks. Check all gaskets before and after carb. Hope this might help

    ARA
     
  5. bushwoods1

    bushwoods1 LawnSite Member
    Posts: 101

    Thanks for the replies. I will check the exhaust port. I have noticed some two cycle oil leaking, but it is rare. May be time to do an overhaul on the carb., and gaskets. May just go with a new carb altogether, just so I can make the small adjustments. ARA why only the one adjustment needle and not both? I would think someone out there would make an aftermarket carb. I'm sure there is enough demand for it. Thanks again for the comments.
     
  6. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,140

    The carb adjustment on the EchoSRM260 does affect the high end speed and I would guess it is the same carb. I don't see a need for both...at least on the newer units.
     
  7. ArchZangel

    ArchZangel LawnSite Member
    from Florida
    Posts: 24

    I agree that the Low speed adj will affect the smoothness of acceleration. But most new carbs have fixed main jet. It's a love/hate relationship. Sometimes I want the adj and sometimes I would just rather clean and inspect the carb. Hha I have never heard of aftermarket carbs for stick equipment. If you knew the cfm rating of the carb i guess you could figure out the requirements of your engine. Find one that matches with H L adj . Zama, walbro, tillotson, nikki, Mikuni and Kehin (sp?) make most of the worlds carbs for small engines.
     

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