clutch slipping on start up and cant run without choke

Discussion in 'Frame Mounted Engines' started by mastermechanic5, May 10, 2008.

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  1. hey guys whats up, i just got my boygofast 70cc engine kit and i must say im lovein it, but i have 2 problems although the clutch doesnt slip when im riding it slips on start up for about 5 feet then grabs and the engine turns over and starts. I already tried adjusting the clutch nut and that didnt help much, i also tried cleaning the pads and disk with automotive brake cleaner and i think that actually made it worse:-| Also when i try to turn the choke of after the motors been running for a wile the engine bogs and runs like **** i richened up the fuel mixture screw and this helped but i was wondering if theres a air leak or some other problem. Sorry i made a new post but i did a search and didnt really find a solution to my problem.

    Thanks guys,

  2. MacTac

    MacTac New Member

  3. I adjusted the clutch nut like 6 times now no matter what position its in the clutch still slips on start up, so as far as the choke problem you just think is a air leak on my manifold? I hope so thats easy to fix =) Another thing in my manual it says that that screw on the side of the carb is a mixture screw and i was messing with it and it had no effect on my idle maybe because my throttle cable is too tight holding open my throttle?

  4. well it turns out that im just a noob and for some reason i thought that the choke in the down position was full choke when it was really choke off so thats no longer a problem, and i took off the clutch plate again and i cleaned it with brake cleaner again and sanded the clutch plate lightly to make it grab better and this made it much better but still slips a little on start up.
    that link didnt seem to have anything on clutch adjustment it just seemed to be about installing chains? any other sugestions?

    Thanks guys,
  5. spunout

    spunout Member

  6. but when i tighten the nut any more the clutch lever gets a looser feeling and the clutch doesnt disengage as much, btw i can't put my clutch in the lock position in order to disengage it i must pull it in all the way, i cant loosen the nut cuz then it wont engage. It seems to me there is more going on then just the clutch nut adjustment any thoughts?

  7. bikeshox

    bikeshox New Member

    I have the same problem as Tom with the clutch slipping. Is there an upgraded clutch spring package that is available? I am assuming to put a heaver clutch spring in you need to split the cases?
  8. It's been quite awhile since I've touched my bike but I think I solved that problem by sanding the friction material and the clutch plate to remove the glazing. If you do find a stronger cluctch spring I don't think you will need to crack the case to change it but I could be wrong.

    Hope this helps
  9. AussieSteve

    AussieSteve Active Member

    bikeshox - Yep, you need to split the cases to replace the spring. The original spring should be strong enough, though. Also, as far as I know a stronger one isn't available.
    More likely there's grease or oil on the clutch pads.
  10. will_start

    will_start Member

    Aren't the clutch pads made from ASBESTOS ?

    in the china kits.

    Sanding asbestos is a no no.

    even i know that one.
    sounds like he had a vapour leak,
    the colour/wetness/spark of the plug,
    this determines what the engine is doing.

    But, I do make claims that I usually get flamed for.
  11. arkives1

    arkives1 Member

    Are you certain you don't have the clutch cable too short? That would hold the clutch partly disengaged causing it to slip on start up but maybe have enough grip to go once you got moving. It's a balance act between the flowe nut tightness and the clutch cable length. Get it too short and you have the problem you have now, get it too long and you can't fully disengage. Good Luck!
  12. danlandberg

    danlandberg Member

    As far as the running with the choke on or partially on, You are getting to much air to fuel mixture when the choke is off. lower the needle clip one notch. That will give you more fuel to air mixture (making it richer). As far as the clutch goes make sure the clutch plate is moving evenly and not binding on one of the three pins.
  13. will_start

    will_start Member

    Not to take over the thread,
    But I have this isue now with my bike, gunna try what you say.

    Maybe before, I had it down one clip and bike wouldn't start easy.
    I Can't remember.

    Hope your bike is working now Tom.
  14. danlandberg

    danlandberg Member

    I am happy with the way it is running now, and no more broken rear studs (yet anyway)
  15. AussieSteve

    AussieSteve Active Member

    Just spotted your post.
    Is it possibly sucking air at the carb/inlet or inlet/cylinder joint?
  16. Al.Fisherman

    Al.Fisherman Active Member

    My thoughts exactly. I feel that if you need the choke (cut air flow off) it"s more then just a needle adjustment.
  17. danlandberg

    danlandberg Member

    Will Start: Try spraying the manifold to cylinder area and the carb to manifold area (W-D 40 will work) or carb Cleaner NOT starting fluid (to explosive).
  18. will_start

    will_start Member

    I been through this whole thing before, with Post's and a vid/pics...if I find those posts,
    I'll punch up a link...