going downhill with HT

Discussion in '2-Stroke Engines' started by pedalpower, Aug 3, 2008.

  1. pedalpower

    pedalpower Member

    I'm breaking in my 66cc HT engine and I have a question about going downhill. I intuition tells me to engage the clutch and let the engine idle until I need the power and acceleration and since I'm moving the engine should be cooling okay. I'm thinking this is better than leaving the engine engaged since there may not be enough gas and therefore lubrication for the speed I am going. I haven't read about this on any tips posting or maintenance threads. If this has been beat to death already could you provide me with a link? I'm looking for the Click and Clack of the MB world on here :) thanks.
     

  2. Simon_A

    Simon_A Member

    If its a decent hill, trust your intuition.
     
  3. Yes. Hold your clutch in. Do my mod. That will reduce clutch cable wear.
     
  4. pedalpower

    pedalpower Member

    you mean moving the clutch arm a couple splines in (picture is which clutch out? yep, all done chief-clutch is a one finger pull. needed to cut about an inch off the return spring for it to be perfect. IMG_0987.JPG . I think I read just about everything while doing my install. thanks to all on this site.

    Also, my tip. with the the type of cable screw clamp that my clutch arm has, I cut a cable cap in half and put it against the arm and soldered it in place-belts and suspenders.
     
    Last edited: Aug 3, 2008
  5. Skyliner70cc

    Skyliner70cc Active Member

    I'm of opposite opinion to leave the engine engaged. There is plenty of oil in the fuel at idle to lube the engine and being at idle, the engine easily dissipates the heat generated by friction. There is little heat being generated by combustion so there should be little risk of engine seizure even at prolonged riding down hill.

    Now, what that said, don't exceed the engien's max rpm capabilities as I did once which cost me an engine my bearing race failed on my wrist pin roller bearings.

    I don't like lockign the clutch out because I have found that there is still some friction between the clutch/flywheel and that this friction could glaze the clutch friction material. Don't believe me, lock your clutch, lift your rear wheel, and rev the throttle. if your wheel spins or moves slightly (make sure you don't have brake drag) you shouldn't coast down hill. If it doesn't, then by all means do as you please.

    PS: I like riding with engine engaged because this puts little more of a load on the chain and in my opinion, helps prevent it skipping off track.
     
  6. pedalpower

    pedalpower Member

    okay, I guess it depends on the hill. So consensus would be:

    1) engage clutch and let engine idle going down hill, only after verifying that clutch is adjusted correctly (no partial/slight friction with lever pulled).

    2) okay to leave engine engaged but don't rev out

    I'm trying to conceptualize my thinking:

    when I am driving down a hill in my car with the foot off the gas the gas consumption goes down to that of idle (.3 gph).

    Now, going down a hill with the HT with engine engaged and no throttle does not seem good because the fuel/oil mixture is not proportional to the speed that the engine is going. to put another way-we know what it sounds like when the bike/engine is being "pushed" by gravity more than being pulled by the engine=engine braking. I've heard engine braking on HTs is not so good, and especially during breaking in.

    So, I think on a hill, i will lock the clutch and it be a bike for a while-with one eye on my chain :eek:
     
  7. graucho

    graucho Active Member

  8. 074KU

    074KU Member

    I am sure I read around here somewhere that engine braking on these little Chinese wonders is neither good nor effective, I cannot for the life of me find the thread :(. That being said I live in some pretty hilly country and leave my engine engaged down hill (however I am running a modified SBP shift kit) at speeds up to 70kph (sadly, faster than my bike can haul my fat ass on the flat) I feel that if the engine is not being "forced" by the chain to run "to fast" its all good, I certainly have never had any obvious damage or any kind of failure using this method for 5+ years.
    Long story short, if your not forcing your engine past max RPM its prolly OK.
     
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