CVT CVT's and Comet drivelines

Discussion in 'Transmission / Drivetrain' started by DetonatorTuning, Mar 1, 2009.

  1. DetonatorTuning

    DetonatorTuning Active Member

    there are more and more posts, pics and expresions of interest in the pocketbike CVT's and Comet Torq-a-verter type drivelines.

    some have already done it and have valuable experience to share, tohers want to and have questions about resources and the mechanics of using them.

    do we need a new forum to serve and encourage the expansion of these efforts ?

    discuss please.


  2. Nuttsy

    Nuttsy Member


    "move along, move along, return to your homes, there's nothing to look at here.............."

    Now where did I see that???
  3. DetonatorTuning

    DetonatorTuning Active Member


    i hope you understood that line in the spirirt it was given.

    you amoung several others have recently surfaced with these advanced configurations just ahead of a few others of us.

    everyones work and the credit for it is and should be theirs to enjoy unless you decide to share them.

    you are amoung the forerunners in these apllications and the rest of us are hoping that you will participate in helping others follow your lead.

  4. mabman

    mabman Member

    The chinese cvt's are essentially junk. The runout is so bad at the cup that it is basically inoperable. We tested two from different suppliers. They are currently sitting in a box in pieces after we tried to straighten them out in a full machine shop and realized they would take a major amount of work to put right. Caveat Empor.

    The smallest Comet is still a size too large for 49cc type engines. I called an engineer there last year and talked to him at length about this and that is the conclusion we came up with. I had one and it was really wide, wider still than the current gearbox/reduction units in use that already cause the need for bent cranks or exercycle one piece cranks. The 340 series was the one we discussed because it has a 5/8" bore. Pricey also.

    There is alot of belt drag with a cvt which reduces efficiency also and the less hp you have to deal with the more this shows up.

    Do as you will but for us it was a dead end.
    Last edited: Mar 1, 2009
  5. Nuttsy

    Nuttsy Member

    No Ill Will

    LOL, I'm just a Nutbuster! Serioiusly! (I don't have a serious bone in me.)

    When I saw that remark, I thought of only 2 things. 1. You thought I was trying to threadjack, which I wasn't. I was only responding to t CVT thread and offering another option and example. The second thought was as you mention; that I was stepping on someone's toes. I didn't realize that this was such a hush-hush topic.
    I will make myself available in any way I can to help others; PM or post. That is why I am responding to these CVT threads, although I am in Beta stage myself right now. However, I like what the CVT has to offer so far. And so do auto manufacturers and scooter makers, etc.
    I am CONFOUNDED why all these guys (and gals) are quick to jump on the shift kit (no offense Pablo/Ghost) since it only addresses the Happy Time motor kit and yet, have, as Mabman, ignored or dropped the CVT. For instance, some time ago, Oct/Nov.-ish, I was learning more about CVTs when lo, one day I saw a post from some guy...eaten by robots or some such, wanting to do something with a CVT. He came over from a goped site and was asking about putting a CVT on a motoredbike of all things. Go figger. Dude was largely ignored as I followed the thread. He put out an invitation for others here to go to his goped site and check out what they were doing with CVTs there. Well I did and there is a WEALTH OF INFORMATION there, albiet pertaining to gopeds not bikes. I drown myself in everything they were talking about and learned much. So much so that I used one in my next build (current).
    MABMAN, you are correct (sort of) that those CVTs are cheap junky things compared to the Comet brand. However, they are easily, tho not too cheaply, made VERY reliable with bearing and seal changes. And for what it's worth, my next build featuring a 2.5HP Harbor Freight Greyhound motor WILL have a Comet CVT (don't know which at this planning stage).
    The main thing about the CVT I am currently using is that it is a DIRECT bolt-up to the smaller engines (Robin, Honda, HS) of which I have the Robin.
    I was asked to start a thread about my build and I might just do that. I won't do it though until I'm sure of what I've got here. As it is, I spent alot of time, energy, and $$$ on my cruiser restore and just don't like the looks of the rack mount. In fact I'm thinking of using a trailer/pusher or sidecar instead (can I mention sidecar, or would that be spilling someone elses beans?)
    OK, this post has gotten way too long.
    In closing, i would like to note that I had the Staton "fiction" drive setup. I liked it--some (typical) drawbacks. It would do 28MPH on level (dry) road...Same engine;chain drive, CVT...same top end (guess I nailed the gear ratio) BUT will wander off on its own without pedaling, although I do just to help it out (it's a pig off the line). But that can be helped with different rollers (can I mention that). Crud, I'm out of the loop as to what I'm supposed to say and not say. Clue me in and we can compare notes.
    If it comes to a vote for a CVT section of the forum, I'm all for it.
    Peace and goodwill
  6. madman this is informative indeed. For the longest time I thought about how easy this would fit my Titan setup with not too much finagling. Probably the biggest mods would be chain alignment or even the possibility with going without the jack shaft entirely for this CVT is reverse rotation just like the 5 to 1 gearbox. And of course some frame stiffing to alleviate the stresses of having the 4 small bolts holding the whole assembly up.
    The discovery of needing extra power to make the belts efficient is news indeed.
    THANKS for saving me 75 bucks for that CVT to cure my curiosity by tackling this yourself!
    Last edited by a moderator: Mar 1, 2009
  7. 5-7HEAVEN

    5-7HEAVEN Guest

    Nuttsy, I'm always looking for ways to harness my twin Mitsubishi engines more effectively. These 2.2hp powerplants are mild-mannered and relatively quiet. :detective:

    I've tried them on friction and chain drive. I have a Titan drive assembly I might use on my girlie cruiser, "The Dragon Lady".

    :idea:Also interested in experimenting with modified Chinese CVT. Thanks for turning us on to them.

    Can you supply us with the goped link? My mind craves knowledge. I love to learn through other tinkerers' projects.:detective:
  8. DetonatorTuning

    DetonatorTuning Active Member


    i guess my humor is just too obtuse for the general public.

    it wasn't about thread jacking or jumping in front of anyones parade. honest, i'm sorry you still feel embattled.

    in the current social/ financial climate all it takes to get alot of attention si to claim there's nothing to see.

    the views on that thread were going about as expected ( slow ) until your pics and my comment, then they picked up real fast. so i asked Tom about starting this thread with a view toward getting as much info out there as possible.

    i was a gopednation member before i came here, i know the info that's over there too, and the success that's been had with the PB CVTs'.

    hope you stick around and add to the discussion.

  9. I am the guy who went crazy for CVTs, and I still love them.
    I posted about how to mod them on Gopednation.
    Here's a link to a search about the CVTs of Goped nation.
    There are a million links I have made and others....
    Page 2 and 3 of the search has a TON of info we've worked out.

    I've realized the easiest way to make it work on an MB
    and figured I'd tell ya'll.
    I share all my info because it's fun, and secrets about stupid stuff like this is silly.

    All you have to do is get it CVT/motor assembly mounted (I'm going to do rack style)
    and then modify the output sprocket on the CVT to accept a #219
    or #35 clutch sprocket (just get the small clutch sprockets from a cart shop
    and weld them onto the old splined sprocket coupler)

    Then just get a large bottom sprocket for 219 or 35 chain(they go up to 100+teeth and only cost in the area of $20 a sprocket on Ebay)
    and bolt the large sprocket to a brake disc rotor attached to the hub.


    This will be the easiest way to get the gearing right without a jackshaft
    or extra gear box.

    Yes the China CVTs are ****, but they last a long time if you do a few mods.

    I plan on doing it soon, but I just figure I'd throw out the easiest solution I've found. You see, I got a scoot that uses the 219 chain, and I've found there are lot of cheap new and used HUGE sprockets out there for it.

    Good luck guys!

    Oh, I forgot one thing...
    I gave a lot of thought to adding a one way bearing on the output shaft,
    and if it could be machined, it would make the CVT almost dragless for pedaling.
    It does have a good amount of drag now for sure.
    Last edited: Mar 1, 2009
  10. DetonatorTuning

    DetonatorTuning Active Member

    thanks for jumping in CBRobots, this could get good yet.

  11. "eaten by robots" lol......
  12. Nuttsy

    Nuttsy Member

    YEAH, HE's the one!!!

    Thanks CBRobots,
    I'm sure I could have searched for your posts but was too lazy I guess.
    I have absorbed much from you (and fellow gopeders) on these things. Any new developments? I'm running a 12 tooth/41 chain sprocket on mine and its doing fine. Although it does whine like a Democrat. I suspect that is that tiny (#11? bearing). And yes, it is not really a pedaler. A freewheel sprocket would be the ticket on these things.
    I hope this area of the forum takes off.
  13. Nuttsy

    Nuttsy Member

    BTW, DT,
    You aren't jumping in front of anyone's parade. This really isn't new ground. I am slightly troubled about your remarks about "credit" and such. Personally, I'm not out for credit. As I mentioned, let me know how I can help.
    Also, shall we continue this here? Or take it to another section of the forum?
  14. srdavo

    srdavo Active Member

    there sure seems to be a LOT of interest, here.

    can y'all post some links to existing MBc threads about CVT's & torque converters, in this thread ?
  15. Nuttsy

    Nuttsy Member

    That's just the problem...there ain't a whole lot. Look down at the bottom of this post at "all" the CVT threads. Pitiful few. And as I mentioned...seems to fall on deaf ears. The robot dude is all over this though. I'll gladly contribute what I know. But I am by no means an authority. Only my personal experience and bias.
  16. Now c'mon...I'll help, but don't get down on my fellow Dems,
    I might have to say that the CVT is made with the same quality as Republican ideas are...... :)
    or..the CVT whines as much as Rush Limbaugh at Cpac... Yeah, that's better.

    Now that we're non-partisan....
    All these CVTs do whine from that gearbox. Synthetic gear oil can help in lessening the whine.
    The stock bearings can sometimes last a long time.

    Do you have any vids with the 12/44?
    Picts of your setup?
    How does it rev?
    What size of shim and how many grams of rollers are you running?
    I just worry that you're running too tall of gearing.
    I'd like to see how it performs up hills....

    Do you have a thread where you posted picts?
    Last edited: Mar 1, 2009
  17. Alaskavan

    Alaskavan Guest

    Captured; why not run the cahin to a sproket on a HD Freewheel hub? Then you wouldn't have to move the engine chain when pedaling. No more drag.
  18. My Front Wheel Drive Buggy Bike is a three speed. I still have my 5 speed hub using the big gear to get my one speed. A CVT would fit rather easily by simply fliping my engine mount plate on my Titan. That would move my engine over enough to align that sprocket to my Jack Shaft. In fact it may stick out far enough to directly link to my sprocket eliminating the jack shaft entirely.

    And drag? Not when it comes to my trike.

    My sprocket freewheels.

    See? Now I want to save that money again for a CVT!

    Last edited by a moderator: Mar 1, 2009
  19. DetonatorTuning

    DetonatorTuning Active Member


    i can see that i'm not making it any clearer.

    Nobody is out to parade their stuff and take credit.

    you were never being accused. there are no subjects that shouldn't be talked about.

    i was the one that said "start a thread about your build it's going to get ALOT of attention "

    i got the discussion started, now i'm going to take a seat and watch.

  20. Tom

    Tom Active Member

    So what would be the official name and description of the forum?

    "CVT's and Comet drivelines"

    Would it go in the garage or clubhouse?