"Compression Braking" and High Revs

Discussion in '2-Stroke Engines' started by mcassMB6, Jul 7, 2008.

  1. mcassMB6

    mcassMB6 Member

    In an effort to spare my brakes I've been using the compression of my engine to slow me ( not on hills). Is this bad?

    Also- I've noticed after I've been crusing/WOT that when I finally come to a stop (intersection, stop light etc). My engine doesn't idle down like it should, instead it stays high revving. What does this mean? Can I fix this?
     

  2. With 2 strokes you have to be careful about "off throttle" braking. These engines LIVE on the oil that is in the fuel. If you are going fast, at no throttle, with clutch engaged, you are supplying the engine with less oil than might be needed as the engine is still turning at high RPM's..
     
  3. stude13

    stude13 Active Member

    yep you can melt it.
     
  4. JohnnyLoves

    JohnnyLoves Member

    Ya can't pull the clutch in with the engine revving at high RPMs either to brake....the shock would damage the engine. I think the best method, especially with stop signs, is to just let off on the throttle little by little.
     
  5. darwin

    darwin Well-Known Member

    Using your brakes might work, try it see if they are worthy of being called BRAKES! LOL
     
  6. mcassMB6

    mcassMB6 Member

    I guess what I meant to say was that even while using my brakes to come to a stop, I'll try to throttle down after an extended period of cruising, when I come to a stop and have to pull the clutch in, the engine is staying in a high rpm. Almost screaming at times.

    The bike has come to a complete stop, and the clutch is pulled in, and the engine sounds like it's still at the last speed I was just driving at. My idle screw is set fine, but it's only happening after a long ride where I've been crusing for a long time.
     
  7. JohnnyLoves

    JohnnyLoves Member

    Are you running too lean?
     
  8. mcassMB6

    mcassMB6 Member

    Impossible...I'm actually too rich if anything. Could that do it?
     
  9. Maybe throttle or cable sticking?
     
  10. HI
    Interesting question but truthfully I have tied compression braking on my bike and it really doesn't seem to offer much in the way of braking....I wonder if sprocket size affects it much?....On thing I did think of but haven't tried (since I have not hooked up my kill switch (I will when I get a chance tho)....I always choke the engine off)....is killing the engine....that should probably give some good braking....Hopefully not so much as to skid the wheel tho.....
    Andrew
     
  11. I wouldnt think that would do much different than just going off throttle to brake Andrew. The one pitfall I can see is when you power the engine back on and release the kill switch after sucking and exhausting all that unburned gas. We used to do that in our manual shift cars in the 70's you get one heck of a pop, one I'm not sure the HT engine would stand up to.
     
  12. Heh...heh...True...I have blown a muffler with a backfire on a truck before...I don't think I wanna grenade the old HT! ;-)

    Andrew
     
  13. There has been discussion and some mods to the engines in the form of a compression release. We used those on motocross bikes way back then for ease of starting and slowing down.....
     
  14. jahmez20

    jahmez20 Member

    From what I understand, 2-stroke engines don't compression brake, that's a feature of the 4 stroke variety.. And yea not to repeat.. But you can burn it up... It's the throttling down little by little that can give your motor more life. I've noticed that my springs don't disengage automatically, I think I need new springs, but I am not sure that you are talking about the same thing I'm experiencing. Maybe you do have a sticky throttle cable.

    James
     
  15. mcassMB6

    mcassMB6 Member

    What is the best way for me to test if I have a "sticky" throttle cable" safely? Can anyone suggest what I should do...
     
  16. jahmez20

    jahmez20 Member

    Throttle cable

    If you can see your where the cable meets the carb, just watch the little lever while you twist the grip, or have someone twist it for you. (WHILE THE ENGINE IS OFF) You should be able to see if it sticks or not. Or, to be safe, just go to your local bike shop and ask if they'll install a new one for you. Should cost less than $20.
     
    Last edited: Jul 9, 2008
  17. You just twist the throttle with the engine off. Does it feel smooth? Does it spin back quickly when you let go. I would check the throttle cable for sharp turns, kinks, maybe pinched somewhere if that is the problem....
     
  18. Huntington

    Huntington Member

    An easy and for sure way to check is by removing the throttle from the HT. Just unscrew the cap the cable is running into, (do not remove the cable, remove the big hex cap). Hold that in your hand and twist the throttle, watch how much play you have, this is also a good time to adjust your throttle tension.