CVT PB/Goped CVT Opinions

Discussion in 'Transmission / Drivetrain' started by DIYMark, Mar 4, 2009.

  1. DIYMark

    DIYMark Member

    Hi,

    I was after peoples experiance/opinions with the Pocket bike CVT's.

    From my understanding the CVT's used on goped are the same as the ones used for pocket bikes? Is this correct? Or are they separate units for gopeds?

    Also, I under stand there are 2 types of CVT's. One with a flat cast aluminium cover and the one with a Plastic chrome/black rounded cover?

    The only difference I can see between these two types its that that one has the "reverse rotation" gearing at the clutch end and the other has it at the output end (sprocket)? Its this all that is different between the 2 cvts or is there more?

    I am asking this because I am intrested in buying one and was wondering if a paticular model was inferior to the other in any way. So, is there any differences in the actual mechanics of both cvts units or do they both use the same variator/pulley setup?

    Ive also heard they thay are ALL junk! However, would $100 including shipping be a reasonable price? Because that how much it would cost me to get one from the US and I cant justify 100 bucks for what maybe junk!

    So please, could any one with information or experiance with these CVT's post up their thoughts.

    Thanks.
     

  2. spad4me

    spad4me Member

  3. DIYMark

    DIYMark Member

    That CVT in the picture looks pretty good... but then so does all the HT and pocket bike engines lol. Anyway, If it comes down to it and the CVT I end buying is ****, I can use the pulleys and machine/fabricate my own CVT I guess. Thanks for the link!
     
  4. That cvt on that link looks like a direct bolt on to my Titan. I'm rather thinking of doing away with the 3 speed hub because I can't find any sprockets bigger than that 19 tooth. The 20 tooth jackshaft sprocket plays some havoc with my current arrangement because it's made for a bigger shaft the adaptor sleeve tends to make this sprocket want to walk away from the jackshaft. No big deal it happens every few days it takes nothing to bring it back on line but it tends to be a bit of a pain. That CVT sprocket can be removed and replaced with the 10 tooth sprocket from my 5 to 1 Titan gearbox then I can remove that 20 tooth jackshaft sprocket and put in my 14 tooth no adaptor sleeve needed after putting back my 5 speed wheel using the big sprocket on there.
    It also freewheels so just throttle and go. And no more adjusting that 2nd gear for when it's off adjustment it will slip.
    I gotta save up for that. Maybe in a couple of months. I gotta get with my curiosity.
    But man if I do this I better get my brakes situated first.
     
    Last edited by a moderator: Mar 4, 2009
  5. Nuttsy

    Nuttsy Member

    DIYMARK,
    Post up a pic/site for the flat cover one. The one 'Spad' posted is the popular one some (including myself) are using. If the flat cover one is the one I'm thinking of, then it is just a gear reduction unit and NOT a CVT. They sell for around $30-ish. Inside the box is just a chain drive from gear to gear. Also, some of these things ARE cheaply made. That is to say the MFG. uses low cost bearings, seals, and such. The ones like Spad linked to is painted silver INSIDE AND OUT. That paint can play **** when it flakes off and gets into the bearings. Ya may want to strip it early on before it can do any damage.The unit as a whole is good though, and you can always upgrade bearings rollers etc. In fact, you SHOULD upgrade some things to "tweak" the unit to YOUR specific needs and engine characteristics. For $70 shipped, IT IS WELL WORTH IT!
    WC
     
  6. DIYMark

    DIYMark Member

    Nah the one with the flat cover is a proper CVT not the chain reduction which Ive seen advertised as a CTV (Heh, sneaky isnt it).

    The only difference between the plastic and metal cover versions is where the reverse direction gear box is. The metal cover one has it at the clutch, the plastic cover one has it at the sprocket. Im 99% sure the interals are identical in both units.

    Oh yea and if I do buy one the mandatory thing I do with all chinese stuff I get is new bearings, seals, lube and a inspection (intresting/pathetic how you buy a HT 80cc and theres swarf in the cylinder and head ahhaha)
     
  7. spad4me

    spad4me Member

    I just received a cvt from a different seller it MAY be slightly higher quality than the one I posted. MAYBE!


    It still looks exactly like the pictire I posted !
    I have never seen the ones you are describing..
    BUT I LIVE IN THE MIDDLE OF NOWHERE.
     
  8. spad4me

    spad4me Member

    It looks like thats dax sells the correct sprocket for the cvt output shaft it is the same as the one for your dax transmission output shaft , Maybe a little grinding.
     
  9. DIYMark

    DIYMark Member

    Heres the metal cover one Im raving on about www.pocketbikeparts.com/product_p/x1tx300987.htm

    Its pretty much the same except cover and location of the geared section. However this version is designed for older bikes so If anyone chooses to buy one, get the rounded plastic cover version (comes in chrome or black colour).
     
    Last edited: Mar 4, 2009
  10. The CVT we use is from an X2 pocketbike.
    Gopeds (only DIY custom ones use them) use the same one.

    That link you just posted sure looks like a gear box, as X1 bikes do not have a CVT

    Can you show an internal picture of the pulleys and belt?
    Is the reduction the same? I've heard that one has more reduction,
    and also has a 3rd bearing support for the end of the variator shaft....


    As for them being junk,
    I ride mine every day. It has lasted just fine,
    though I do have to tweak it sometimes. Tuning is key,
    if you don't get it tuned in right for your engine, it will be worse than
    not having a CVT at all.
     
    Last edited: Mar 4, 2009
  11. DIYMark

    DIYMark Member

    Hmm, Ive screwed up lol. I origianlly thought that the "fake" CVT LIKE gearboxes were the ones with the 3 pulleys and chains in them...however after more research to one I posted a link to was in fact just a gear box lol!

    Anyway, should I get one I will definatley tune it correctly (once the engine mods are complete so my power band stays put lol!). Tuning will be easy as I can machine my own variator weights.

    Lastly, does anyone know what the ACTUAL gear ratios are. The website say approx 7:1 and people here have mentioned something around 6.5:1...okay.

    But does anyone know the gear ratio when the variator is fully closed (ie say teh engien is a redline and the CVT is in "overdrive"). Whats the ratio then? 1:2 (0.5:1)?

    Oh and heres a good supplier if you want to pay with paypal, also they ship international!!!

    http://www.pocketbikeparts.com/CVT_p/x2tx300627.htm

    For me (in Aus) and with our exchange rate, a CVT will cost me $120. Coupled with a FULLY modified PB engine my build so far will cost $500 and thats without the bike!
     
    Last edited: Mar 4, 2009
  12. I didn't want to out and out say you were wrong about that X1 box.
    There is a CVT out there that has a metal cover,
    and it is a weird CVT, one of my friends at GPN found it.
    It had bigger gear reduction, and the third bearing like I said.
    I haven't seen one since.

    I sadly cannot tell you the exact ratio.
     
  13. spad4me

    spad4me Member




    By actual count on a fancyscooter cvt.
    The transmission part is 3 to 1
    The cvt part is hard to do. But here I go 3 to 1 .

    Errors possible it is hard for me to check this safely.

    So with belt errors about 6.5 low to 3 to 1 at high.
    With 5 to 1 transmission like a thats dax titan kit with a built in jackshaft.
    You get better low end with much better top end.
    You may need a larger rear sprocket.
     
  14. Nuttsy

    Nuttsy Member

    On my CVT, in low range I counted the revolutions and got right at 7:1. I know for a fact they will not go 1:1 or .9 like the Torque-A-Verter advertises. Just watching the belt at high revs looks like it MAY get around 2 or 3 or there abouts. Like Spad says, there are most likely variations from unit to unit. I would think that maybe with some shimming you might squeeze the belt a little higher. Not ready to disect this thing yet tho but playing with the rollers might be the easiest way to get the response where you like it.
    WC
     
  15. DIYMark

    DIYMark Member

    ...when watching the belt you get 2 or 3...

    Is that the final drive ratio? Or does it look like the CVT section (2 pulleys/belt) are giving a 2:1 ratio (approx) in "top gear"?

    I think (but then again Ive never seen/used one of these), that the actual CVT section can get to around 0.9:1 in overdrive BUT once this ratio comes out through the gearbox section of the CVT it turns out to be around 3:1 (Is this correct?)

    Im gonna crunch some numbers now to figure out what my final drive ratio should be (assuming ~7:1 at the start).
     
  16. Nuttsy

    Nuttsy Member

    I'm talking about visually observing the belt. It does NOT quite go even (parallel) between the pullys. As mentioned above the Torque-A-Verter brand CLAIMS .9:1. Don't know. Don't have one of those.
     
  17. DIYMark

    DIYMark Member

    Not even parallel...Hmm...Im still not detered lol. Ill grab one for the next build!
     
  18. Look guys,
    I'm someone who has put at least 500+ miles on mine.
    They are great little cheap things.

    Parts like the variator shaft could be remachined easily with a small lathe,
    and most parts in it can be trued up by bending one way or another.
    The housing is very cool, and with some mods I can honestly say that this is the most valuable addition to any motor under 4hp.

    Over 4-5hp it starts to be redundant, as it starts to tear the CVT up
    and it's really not needed.
    For a 1-3hp engine it's stupid awesome.

    And, if you buy one, have an impact wrench for vari and driven pully nut removals.
     
  19. Or replace the output 10 tooth jackshaft sprocket to a 12 or 14 tooth!
     
  20. Nuttsy

    Nuttsy Member

    Go ahead and get it; you won't be sorry. Ya can kick the numbers around all you want. But, if ya need me, I'll be out riding mine.
    SeeYAAAAAAHooooo!
     
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