Chain does not fit rear sprocket - please help

Discussion in 'Frame Mounted Engines' started by atomicmiata, Aug 27, 2008.

  1. atomicmiata

    atomicmiata Member

    I just bought an engine kit off ebay from boygofast.
    an 80cc kit. (I know it is probably -70cc)
    the chain pitch does not jive with the rear sprocket pitch.
    (it appears that the chain would need to stretch considerably to fit)
    anyone seen this before?
    should I buy a new chain? what size?
    or buy a new sprocket? if so, from where?

    photo below:

    best regards,
    steve in frederick, md

  2. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Have complained to boygofast yet?

    Have him send you the right parts or he gets a negative
    Saying he has no warranty is one thing but this is different

    Measure the pitch on the chain
    Stock chains are junk anyway

    probably the machining on the sprocket is off

    How does it fit on the front sprocket?

  3. HoughMade

    HoughMade Guest

    Agreed- likely a rear sprocket issue, but one that could be solved with some grinding- just taking off some edges and chrome plating on the teeth can do wonders.
  4. s_beaudry

    s_beaudry Member


    You are talking about someone who thrives on negative feedback and not answering ANY emails!

    May need to rethink this idea!
  5. relaxxx

    relaxxx Member

    Forget the 44T, get at least a 36t. I'll never go back to 44 again. It's a crime against nature, those sprockets.
    Last edited: Aug 28, 2008
  6. atomicmiata

    atomicmiata Member

    44T sprocket

    well I live on a steep mountain and perhaps I need it geared down.
    I will trade off not pedaling uphills for lack of top speed.
  7. atomicmiata

    atomicmiata Member

    420 size chain fits the sprocket pitch

  8. HoughMade

    HoughMade Guest

    #41- about the same outside width as the standard 415, wider between the plates, but the outside width is what you are concerned about. About $13-$14 for 10 feet at Tractor Supply or lowes or any small engine shop.

    However, I would still knock the rough edges off the sprocket.

    Curious- were yopu able to get the chain to seat when the sprocket is off the bike- in other words, can you get several links in a row to fit the sprocket?
  9. atomicmiata

    atomicmiata Member

    no, the stock chain will not seat into the teeth around the sprocket all the way.
    I guess the supplied kit chain is not a 415 as it supposed to be...
  10. HoughMade

    HoughMade Guest

  11. jwbiker58

    jwbiker58 New Member

    Same problem!!

    I too bought one of the 80cc boygofast kits and have the same problem the chain fits on the engine sprocket but even after considerable filing to remove burrs and sharp edges from rear sprocket chain just won't lay right. (wrong pitch)
  12. jwbiker58

    jwbiker58 New Member

    420 chain fits???

    I must be missing something here. The kit was advertised as having heavy duty 415 chain, I haven't used a micrometer on it but best I can tell it appears to be what it says. Given that, how does a 420 chain fit? unless the sprocket is too thick cause the rest of the dimensions are the same! right?????
  13. atomicmiata

    atomicmiata Member

    as suggested here, I bought the #41 chain from tractor supply and it fits fine, and I even have the balloon tires on so it can be quite a clearance challenge!
    I got the bike running today for the first time and it works great, so don't get too discouraged...

    thanks for everyones help here on the board.

    -steve in frederick
  14. atomicmiata

    atomicmiata Member

    I don't think the supplied chain was 415 (as it should have been) or it would have fit.

    I first purchased some 420 chain which was a good fit pitch-wise but ended up being too wide to clear the balloon tire. then ended up with 41 chain from TSC

    -steve in frederick, md
  15. jwbiker58

    jwbiker58 New Member

    TSC here I come!

    looks like I'll be heading to TSC for some replacement chain. blows though that kits are furnished with garbage! I wonder if they are open tomorrow? :rolleyes: Hmm! I noticed that lots of posters here recommend replacing all engine studs, bolts and nuts and using locktite on them. I was just wondering if you did all that? I can see putting blue removable loctite on the ones most apt to vibrate loose like exhaust & intake head bolts & such but why replace them with some other chinese bolts cause I guarantee most of the stuff you buy in the hardware store these days is made there just maybe made to closer tolerance & specs.:???: maybe I'm just being pessimistic though. wonder if TSC has metric bolts & nuts?:confused:
  16. atomicmiata

    atomicmiata Member

    not yet. I will do that. I first wanted to see if it would start and run before I dug down any deeper. and it runs great.

    the exhaust pipe keeps coming loose even tho it has gasket RTV and blue loctite on the threads and it is double lock nutted...

    -steve in frederick md
  17. HoughMade

    HoughMade Guest

    The supplied nuts and bolts are soft, strip threads more easily and break more easily.

    Go ahead and give them a try if you like, though.

    TSC does not usually have a good selection of metric hardware- Ace, however, is excellent.
  18. jwbiker58

    jwbiker58 New Member


    Made the run to Tractor Supply and picked up their last 10ft coil of #41 chain. Whew! that was close!! no metric nuts/bolts whatsoever though! chain from TSC is obviously much better quality than the chain in the kit however stamped right on the links is that word "CHINA" absolutely incredible how much difference there can be in quality! As far as the nuts and bolts thanks for the tip on ACE however our local Ace decided to switch to TRUE VALUE and start a small engine shop and since then you can't find even the simplest things there! they are too wrapped up in working on bubba's chainsaw or commercial zero turn mowers. Lowes and Home Depot have better hardware selections. This town would be a great place to start a good hardware store! we do however have a Fastenal and though they are a bit pricey I'm sure they will have what I need! So anyway, put the chain on, mixed up some fuel, and tried her out engine came to life quickly and seems to run fairly smoothly for a two stroke! put about 5 miles on her without any major failure, however the clutch cable stop slipped on the cable and I was unable to disengage from the engine toward the end. the whole family wanted to ride great fun!!