Valve noise?

Discussion in '2-Stroke Engines' started by CPC, Apr 9, 2009.

  1. CPC

    CPC Member

    I just got a 66cc kit last week, and I have recently noticed what I believe to be the valves making some noise. I am wondering if this is normal. I was running a gas/oil mix @ 32:1 for 1 gal, but last night I upped it to 20:1 for a "just in case" safety net. Has any one else had this problem, and if so how do I go about fixing it if its something bad?

  2. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Your 2 strokes doesn't have valves.....
    It's a piston port engine

    What does the noise sound like?
    When does the noise happen?
    Do you hear the noise when it is idling?
    or under load?

    Most of the noise on your motor comes from the clutch (right side) cover

    Did you grease the gears in there?

    How many miles or tanks of gas have you used?

    32:1 for 1 gal is too lean for breaking the motor in

    Did you use a richer oil mix to start?
    Last edited: Apr 9, 2009
  3. CPC

    CPC Member

    ive listend and it sounds like its coming from the engine head....happens at high mid and high rpms.
    I have never greased the plastic gears on the right side, I have been wondering it I should or not. the sound I think, sounds like valves pinging but if no valves cant be that. has been NO help at all.
  4. Mountainman

    Mountainman Active Member

    those HT engines are known to be just a little noisy anyway

    not to sure that I would even worry about it -- if it's running alright

    and as our vendor mentioned -- grease that thing

    ride the motor bike THING
  5. arceeguy

    arceeguy Active Member

    At idle with the clutch disengaged, there is a certain amount of metallic noise coming from the gear cover area that is considered normal. Does the noise change under load? If you are hearing a "pinging" at mid-high RPM when the throttle is open, you could be hearing detonation (pre-ignition) from a lean mixture. Does the engine run/smell hot after you drive at moderate speeds for a while? Does the engine run better at 3/4 throttle than at full throttle? If so, you need to drill the main jet out to enrich the mixture at high RPM.

    Also make sure that the noise isn't something on the bike rattling at a certain RPM.

    Good Luck!
  6. CPC

    CPC Member

    I believe all of what you are saying is my problems. I tried bputting some cardboard on the clutch colver, but I did not notice a difference. Going to try some car stero dynamat and greasing the clutch gears today....least the grease. As to drilling the main jet, how do I go about doing that? My spark plugs are dry, but somewhat carbonated they dont look bad thoug Im getting new one today, hopefully! However my engine does not get hot....can usually touch it, its the exhust that gets HOT burns every pair of pants I own so far :sweatdrop:
  7. fetor56

    fetor56 Guest

    Try tightening the head,but NOT overtight or you'll strip the threads.HT heads have a BAD habit of loosening-off quickly.
    If that's not the problem check to see if the exhaust gasket isn't leaking.
    Grease the gears occasonally.
  8. CPC

    CPC Member

    just got a brand new exhust gasket yesterday that is fine, also just had the head bolts checked @ the local motorcycle shop, there @ 12.5 lbs each. I did notice the chain tensioner is getting VERY noisy, but I can seem to get the chain tight enough to get rid of it completly cant get a 1/2 link anywhere here for my chain....
  9. fetor56

    fetor56 Guest

    Get a spring-loaded chain tensioner....Dirt Bike shops should sell them.
  10. CPC

    CPC Member

    was just there DOH! did get some fiberglass muffler packing and good 2-cycle oil...oing back saturday and will try then thanks
  11. arceeguy

    arceeguy Active Member

    The dynamat will reduce the clatter at idle, and the gear whine to a certain degree.

    The danger is in the possibility that the engine is "leaning out" at high revs/load.

    I have found that the "80cc" (66cc) models tend to run a bit rich at idle/mid range, but lean out as RPM's go up.

    To check idle mixture, warm up the engine and shut off the fuel valve. As the fuel bowl runs dry, the engine RPM should rise slightly before the engine stalls. If the engine RPM's rise quite a bit before the engine stalls, you need to lower the jet needle by raising the c-clip a notch and re-testing.

    To get rid of the "lean bog" at high RPM, I use a .80mm miniature drill in a pin vise to open up the main jet. Some people here have reported that their carbs are jetted too rich, so be sure that yours leaning out at top RPM. If your engine has more power at a lower setting than WOT, it is too lean. Continued operation will eventually kill the engine.

    The problem with the rich low end is that it can fool you into thinking the mixture is rich enough because the plug might be wet with oil.

    I've read that the problem lies in the fact that many factories use the exact same carb regardless of engine displacement, and the carb is designed for 50cc engines.

    To add to fetor56's suggestion, replace the acorn nuts with standard hex nuts with washer and lockwasher, and torque to 12 lb/ft in several stages. (in an X pattern)
  12. CPC

    CPC Member

    My engine did not have acorn nuts on the head or and part of the engine except the intake.....where can I get a 66cc carb that is NOT HT, I want aftermarket.

    I tried the thing you said about running the fual bowl dry yesterday, and I did not notice rpm's increase at all, it just all the sudden quite after about 5 minutes.
  13. arceeguy

    arceeguy Active Member

    In which case, raise the jet needle. This will fatten up the mixture on the low/mid range but re-jetting is the only way to fatten up the top end.

    What brand of engine did you end up with - a Grubee, or a GasBike "house brand".

    I don't know of any aftermarket carbs that will jut "bolt on" and go. :(
  14. fetor56

    fetor56 Guest

  15. biketec

    biketec Member

    Sure there is you can get the CNS carb. I'm out but spooky has'em or try a 13/13 off a vespa bravo.
  16. arceeguy

    arceeguy Active Member

  17. CPC

    CPC Member

    ill have to get one along with a 36 tooth sprocket
  18. Irish John

    Irish John Guest

    Running the engine new on 32:1 might have caused some damage - especially if you revved it up too high. They take 500 kms to run in at about 25 km\hr max speed and at a mix of 15:1. A metallic noise could be a piston ring - I've had them go right from the first week.
    Hard to tell.
  19. danlandberg

    danlandberg Member

    First of all 32:1 is not enough oil to gas for break-in. THEY say 16:1 for the first gallon ( two tanks ) aprox. Your at less than 1/2 that. But I'm old an stupid! I belive in the old world ways......Break it in the way your going to Ride It!!!! Good Luck
  20. TrumpsGold

    TrumpsGold New Member

    Not enough oil

    I have a friend breaking in her motor at 32 to 1. After a short ride on the bike it started to leak oil from around the head. It also doesn't sound normal for a two-stroke...

    What do you think is wrong with this motor? If it is a ring or two are they cheap? Is this a fairly easy fix?

    Thanks in advance! :confused: