piston slap or engine knock?

Discussion in 'Engine' started by yfzrider310, Jul 20, 2009.

  1. yfzrider310

    yfzrider310 New Member

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    Is there a good way to tell the difference between the two? I can't tell. Just at idle its really noisy. I'm not sure what to do. I know if its a piston slap it needs boring and a rebuild. It has a rebuild with about 20 min. on the piston because its never been ridin ever since the rebuild. It just doesn't idle but it runs but as soon as you let off the throttle it dies. Whats the problem there also? Sorry if im not making sense. I think for the idle problem it needs a tors removal kit. Is that what I should do?
  2. yb200

    yb200 New Member

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    blastys are really noisy at idle...turn the idle up so it dont die
  3. mystahagy

    mystahagy New Member

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    Pull your exhaust pipe off and stick a finger in there. See if that piston has some play in there by pushing it back. Cycle it a time or two with the kickstarter with your finger out of course, and try again to get a good feel for it.

    New rebuild? Give some more details on your build, and this may be a silly thing but make sure you are using a BR8ES or B8ES plug. Some plugs are longer and I've personally seen the local auto shop have the WRONG cross reference part number on these NGK's.

    Lastly, your carb may just need some tuning and you aren't used to the loud nature of these motors. How loud is this, a loud click/tap or something like a hammer hitting the frame?
  4. doc_speeder

    doc_speeder New Member

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    OUCH! Holy crap would that make a mess of your finger in a hurry!!!:eek:

    They are pretty noisy motors. I think 'cause they're air-cooled, there's no water jacket to muffle the mechanical sounds. Maybe the fins amplify it too? Mine makes kind of a "whirring" sound at idle. It's all good, the sound hasn't changed since I bought it, and I can hardly hear it with my helmet on:D
  5. super noober

    super noober Can't Stop, Won't Stop!

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    mine did the exact same thing, take your seat off and lift the little rubber flap thats there, you will see a big flat head screw sticking out of your tors unit. thats your idle screw, turn it up and that baby will idle nice. start small and play with it untill you're happy with the way it sounds.
  6. royalt67

    royalt67 New Member

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    Yeah, air cooled moters have a bit more clearance built in to compensate for the extra expansion. Result = engine noise.

    Did you use a new carb or mess with the TORS? If you disconnect the carb, but not the throttle switch (and jump it) the throttle will open the switch and kill the motor when you release the throttle lever.
  7. yfzrider310

    yfzrider310 New Member

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    Thanks for all the help. I think its just the engine being noisy but I will check by taking off the exhaust. My main problem now is that the thing will run good with a slight amount off throttle, but no throttle it shuts off immediately. I have read up on this and I think its just the t.o.r.s. Another thing I cannot adjust my idle because my buddy stripped out the idle screw somehow so I have no adjustment.X( Is that my problem? The only way to adjust the idle is by spinning the carb further from the tors unit. This should be all solved by a tors removal kit right? I've been looking at the vito's with the idle screw kit. Should that work? Thanks for all the help again.
  8. mystahagy

    mystahagy New Member

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    Sounds like you might need to just bump up the idle. Stripped out your idle screw? Could you be talking about the air/fuel screw on the side maybe? Your idle adjustment is a knob up on top of your tors, just pop the seat off and there it is. Easy to adjust with a flathead screwdriver.
  9. ruthless_one3k

    ruthless_one3k Member

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    I had the same problem with mine. Look up blaster walk around on youtube and most of them make the same sound. one thing that can cause a little extra noise is the counter balance shaft sprocket. I has rubber dampers in it and is held together with 3 rivets that for some reason seem to be worn out on most older blasters.
  10. yfzrider310

    yfzrider310 New Member

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    Nope the one under the seat is stripped out.:(
  11. royalt67

    royalt67 New Member

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    sounds like you have multiple reasons to do a TORS removal! :-D

    For now though, unplug the carb. and unplug and jump the wires to the throttle switch.
  12. just_ride_595

    just_ride_595 New Member

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    try grabbing the outsides of the tors idle knob with some good pliers.

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