Centrifugal 2 stroke HT - Centrifugal Clutch + Pull Start

Discussion in 'Transmission / Drivetrain' started by grummy, Aug 14, 2008.

  1. grummy

    grummy Member

    Is there any centrifugal clutch and pull start for 49cc Happy Time engine?

  2. jboisclair

    jboisclair Member

  3. Many of the Bigger Venders Will be selling a Dual start Ht motor In about a month.It's available For Purchase Now But shipping will not start for close to a month.

    The past pull start mechanisms available for-sale currently are Undesirable to say the least.After 20 or so pulls they fail.

    Apparently the new pull start mechanism has been updated and improved.

    Yes i will have them as well.
    Ill post some pictures And Videos In the next couple days if i get a chance.




    Last edited: Aug 16, 2008
  4. I have a pull start on mine, it is TERRIBLE!! That is it broke after 5 pulls, fixed it, 10 pulls later another part was broken .. so now i have machined some bits and a lot of glue and so far it hasnt failed for god knows how many pulls! a lot!

    hopefully new design will be better
  5. jmccrury

    jmccrury Member

    Can a HT motor still be started while pedaling if a centrifugal clutch is installed, or is a pull start required?
  6. Nope, centrifugal clutches cannot be pedal started, PULL START ONLY i'm afraid! Pull starting is so much nicer i think, my chain tensioner comes loose with too many bump starts .. but it does add an inch or 2 to the width of engine so pedal clearance becomes an issue
  7. jmccrury

    jmccrury Member

    Thanks for the help. I have been thinking about ordering a centrifugal clutch for mine since I found out they were available, but didn't know if I would have to order the pull start too. I will also have to check out the clearance issue.
  8. Drunkskunk

    Drunkskunk Member

    any have the centrifical clutch available as parts to upgrade an exsisting HT?
  9. Yes most Big Venders Will have the Updraded kits for around $50..

    I have them but the Newer kits are still in the trial period.

    Going thru a BlueCollar Beating !!


  10. terrence

    terrence Member

    I added the pull start for my 70cc. I had to add the wider peddle crank because the
    pull start was in the way after adding it. Yes, they are kind of junk. Mine lasted 1 month of
    medium use before it broke. I fixed it and sold the bike to a neighbor.Its been ok for him since .Just a thought.
    Last edited: Sep 19, 2008
  11. arkives1

    arkives1 Member

    centrifugal clutches

    I have centrifugal clutches on two engines, both also have the standard clutch that comes on the engine, and yes I can pedal start either of them if I choose. I too had to add the wider crank because both the centrifugal clutch and the pull starter will hit the pedals with out the wider crank. In rural areas the pedal start is fine for me but here in the city where I make a heck of alot of stops on every ride, the centrifugal is a wonderful addition. I'll add both items to my 3rd build if I can get pedal clearance. The latest bike is an OCC Chopper and it presents plenty of challenges. Haven't started it yet but have been reading what others experienced.
  12. Skyliner70cc

    Skyliner70cc Active Member

    Really, been pedal starting both of my centrifugal clutch engines for months now.

    The pull start works great once you replace the lousy rope with something better.
  13. arkives1

    arkives1 Member

    Pull start and centrifugal clutches

    I don't know what kind of engines won't work with both starting methods. I have two bikes and both can be started either way. I agree with skyliner that the darn pull starters are pretty flimsy. The last one I got seemed to have a decent rope and the little tab that engages the engine seems to be a bit heavier but still appears to be plastic. I'll probably end up fabricating new tabs for them eventually.
  14. cpuaid

    cpuaid Member

    Skyliner70cc and Arkives1... thanks for the heads up on the info. was gonna do the pull start upgrade but didn't realize the assembly was so flimsy and that it may require a wider crank. helped install a centrifugal clutch and it was a pain in the rear.
  15. iron_monkey

    iron_monkey Guest

    Main problems:

    Sometimes the clutch makers haven't pre-bored the bushings so the clutch bushing can't slide down on the crankshaft enough, the result is that the clutch sticks out so much the clutch cover cant even go on and the gears dont overlap enough. You will need to bore it out with a grinder if thats the case.

    Sometimes the clutch gear can sever itself from the clutchbell, maybe the clutchmakers didnt put enough epoxy glue. In that case you will need to somehow weld/braze it back in, or glue it back in with JBweld or some other high temperature epoxy(I did this). To be safe epoxy must be able to withstand over around 400F, I bought an epoxy that was only 300F and it failed. Perhaps the clutch got too hot (it does get very hot - untouchable hot), or maybe I simply havent washed it properly(I should have directly put detergent on the bonding surfaces as theres an oily film thats fairly hard to wash off). The last time I did directly put detergent on the surfaces in washing.

    Sometimes the inner clutch assembly simply isnt made properly and it vibrates too much while engaging or at low throttle. I dont know what exactly causes it, I just bought another clutch.

    From another thread, it appears the main bolt must be loctited, otherwise you may get a cracked bushing. Do not excessively torque the bolt either, it must be firm, but dont need to use all of your strength.
    Last edited by a moderator: Nov 5, 2009
  16. arkives1

    arkives1 Member

    Great information IronMonkey. I haven't had a clutch failure yet, I did have one defective centrifugal which was replaced immediately by Powerking. I still have one engine which has a small gear that I cannot remove yet.It needs to come off so the centrifugal can go on.